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Electrolytic Synthesis and Characterizations of Silver Nanopowder
Theivasanthi, T.; M. Alagar
This work reports a simple, novel, cost effective and eco-friendly electrolytic synthesis of silver nanoparticles using AgNO3 as metal precursor. The synthesis rate is much faster than other methods and this approach is suitable for large scale production. They are characterized by XRD, SEM and FT-IR techniques to analyze size, morphology and functional groups. XRD studies reveal a high degree of crystallinity and monophasic Ag nanoparticles. Their particle size is found to ...
Electrolytic Synthesis and Characterizations of Silver Nanopowder
Theivasanthi, T
This work reports a simple, novel, cost effective and eco-friendly electrolytic synthesis of silver nanoparticles using AgNO3 as metal precursor. The synthesis rate is much faster than other methods and this approach is suitable for large scale production. They are characterized by XRD, SEM and FT-IR techniques to analyze size, morphology and functional groups. XRD studies reveal a high degree of crystallinity and monophasic Ag nanoparticles. Their particle size is found to be 24 nm and specific surface area (SSA) is 24 m2/g. Analysis of Ag nanoparticles SSA reports that increasing their SSA improves their antibacterial actions. Microbiology assay founds that Ag nanoparticles are effective against E.coli and B.megaterium bacteria. SSA of bacteria analysis reveals that it plays a major role while reacting with antimicrobial agents.
The rheology of oxide dispersions and the role of concentrated electrolyte solutions
International Nuclear Information System (INIS)
Stability control of particulate dispersions is critical to a wide range of industrial processes. In the UK nuclear industry, significant volumes of waste materials arising from the corrosion products of Magnox fuel rods currently require treatment and storage. The majority of this waste is present as aqueous dispersions of oxide particulates. Treatment of these dispersions will require a variety of unit operations including mobilisation, transport and solid- liquid separation. Typically these processes must operate across a narrow optimal range of pH and the dispersions are, almost without exception, found in complex electrolyte conditions of high overall concentration. Knowledge of the behaviour of oxides in various electrolyte conditions and over a large pH range is essential for the efficient design and control of any waste processing approach. The transport properties of particle dispersions are characterised by the rheological properties. It is well known that particle dispersion rheology is strongly influenced by particle-particle interaction forces, and that particle-particle interactions are strongly influenced by adsorbed ions on the particle surfaces. Here we correlate measurements of the shear yield stress and the particle zeta potentials to provide insight as to the role of ions in moderating particle interactions. The zeta potential of model TiO2 suspensions were determined (Colloidal Dynamics Zeta Probe) over a range of pH for a series of alkbe) over a range of pH for a series of alkali metal halides and quaternary ammonium halides at a range of solution concentrations (0.001 M - 1 M). The results show some surprising co-ion effects at high electrolyte concentrations (>0.5 M) and indicate that even ions generally considered to be indifferent induce a shift in iso-electric point (i.e.p.) which is inferred as being due to specific adsorption of ions. The shear yield stress values of concentrated titania dispersions were measured using a Bohlin C-VOR stress controlled rheometer. The shear yield stress of a material is defined as the minimum applied shear stress required to induce flow. The yield stress vs. pH curves obtained reflected the shifts in i.e.p. seen in the zeta potential results. Interestingly, specific ion adsorption results in an unexplained increase in the value of the yield stress over that expected for simple systems with no such interfacial ion adsorption. Possible reasons for this effect such as ion-ion correlation effects are discussed. The importance of this increased attraction for the mobilisation of settled solids in an aqueous environment and especially the likely effects on the treatment of Magnox fuel waste materials is discussed. (authors)
Synthesis of and characterization of lithium ceramic electrolytes
Rangasamy, Ezhiylmurugan
The depleting fossil fuel reserves, rising oil prices and the need for reduction in CO2 emissions have created an unprecedented impetus for vehicle electrification. Lithium batteries have the highest energy density of the various available battery technologies. They are the most promising battery candidate to enable Hybrid Electric Vehicles (HEVs) and Plug-in Electric Vehicles (PEVs). However, current Li-ion current battery technology is costly and requires a significant increase in energy density to achieve range comparable to conventional gasoline-powered vehicles. Advanced lithium battery technologies such as Li-S and Li-O2 could potentially offer significant improvements in energy density to address the limitations with current Li-ion technology. The implementation of these advanced battery technologies, however, has been limited by the lack of electrolyte technology to enable the use of metallic lithium anodes. Thus, there is a clear and compelling need to develop new electrolyte materials that exhibit the unique combination of fast ion conductivity, stability against lithium, air and moisture. Lithium Lanthanum Titanium Oxide (LLTO) and Lithium Lanthanum Zirconium Oxide (LLZO) have been identified as viable candidates for the advanced battery technologies. However, issues concerning phase purity and densification warrant developing new and novel synthetic techniques. A single step procedure has been developed for the synthesis of Lithium Lanthanum Titanium Oxide (LLTO) membranes. The single step procedure combines phase formation and densification of the ceramic electrolyte in a hot pressing technique. The effect of synthetic technique on relative density, grain structure and ionic conductivity of the LLTO membranes has been explored in detail. The critical step of synthesizing cubic Lithium Lanthanum Zirconium Oxide (LLZO) has been systematically studied through the controlled doping of Al, using X-Ray Diffraction (XRD) analysis. Effects of Li and Al concentration on the crystal structure of LLZO were also studied in detail. Critical dopant concentration of Al to stabilize cubic LLZO was established during the course of this study. Systematic doping studies on the 24c site of La3+ in the primary lattice have also been explored in detail using XRD analysis to improve the ionic conductivity by maintaining the Li sub-lattice free of dopants. It is hypothesized that the supervalent substitutions create Li vacancies in the sub-lattice promoting disorder, thereby stabilizing cubic LLZO. While Ce4+ substitution for La3+ proved to be effective in synthesizing cubic LLZO, precipitation of Ce4+ observed under Backscattered electron (BSE) imaging limited its ionic conductivity. In an effort to develop flexible, solution-based synthetic techniques, two novel processes were established to prepare low dimensional, cubic LLZO powders. Hot pressing of the synthesized LLZO samples yielded high relative density (>95%) ceramic electrolyte membranes. Arrhenius studies using EIS to measure activation energy revealed and empirical relationship between the grain size and activation energy for dense LLZO membranes.
Electrolytes and Electrodes for Electrochemical Synthesis of Ammonia
DEFF Research Database (Denmark)
Lapina, Alberto
In order to make Denmark independent of fossil fuels by 2050 the share of renewable energy in electricity production, in particular wind energy, is expected to increase significantly. Since the power output of renewable energy sources heavily fluctuates over time there is a pressing need to find effective energy storage solutions. Production of synthetic fuels (e.g. ammonia) is a promising possibility. Ammonia (NH3) can be an interesting energy carrier, thanks to its high energy density and the existence of well developed storage and transportation technologies. However the present-day production technology is based on the Haber-Bosch process, which is energy intensive and requires large-scale plants. One possible way to produce ammonia from sustainable electricity, nitrogen and hydrogen/water is using an electrochemical cell. This thesis studies a number of electrolytes and electrocatalysts to evaluate their applicability to electrochemical synthesis of ammonia. First a number of potential electrolytes areinvestigated in the temperature range 25-400�C in order to find a proton conductor with a conductivity higher than 10-4�S/cm in dry atmosphere (pH2O�< 0.001 atm). The conductivity of materials prepared from FeOOH nanoparticles is measured at 25-40�C between pH2O�= 0.037 atm and pH2O�< 0.001 atm. The conductivity is low in dry air (10-6-10-8�S/cm), while it can be up to 7�10-3�S/cm in wet air. The conductivity of Y-droped Ti, Si, Sn, Zr, Ce pyrophosphates, Gd-doped cerium phosphate and cerium pyrophosphate - KH2PO4�composite is measured at 100-400�C at pH2O�from 0.2 atm to below 0.001 atm. The phase stability and long term conductivity of the compounds with the highest conductivities are investigated, and conductivity is found to depend heavily on pH2O�and phosphorus content. High temperature solid state proton conductors are briefly reviewed and defect chemistry and partial conductivities of Y-doped BaZrO3-BaCeO3�solid solutions are studied as a function of temperature, pH2O�and chemical compositions by means of defect chemistry modelling. BaCe0.2Zr0.6Y0.2O2.9�(BCZY26) is chosen as electrolyte, and used to fabricate symmetrical cells with composite metal-BCZY26 electrodes. Two metals (iron and molybdenum) are tested as electrocatalysts: the choice is based on the use of catalysts in the Haber-Bosch process and density functional theory calculations. The symmetrical cells are tested at OCV (i.e. without polarization) by impedance spectroscopy in dry H2/N2�and H2/Ar atmospheres, in the temperature range 440-650�C for Mo-BCZY electrodes and 350-500�C fir Fe-BCZY electrodes. No clear evidence of activity of Fe and Mo towards nitrogen reduction to ammonia is found. The kinetics of the electrode reaction (hydrogen oxidation/reduction) at the Mo-BCZY electrode are studied in detail by impedance spectroscopy to identify the electrode processes. Further studies carried out under polarization will be necessary in order to fully assess the potential of Fe and Mo as electrocatalysts for ammonia synthesis.
Synthesis, rheology and forming of Y-Ba-Cu-O ceramics
Energy Technology Data Exchange (ETDEWEB)
Green, T.M.
A chemical synthesis route is discussed which results in a low- temperature precursor to Y-Ba-Cu-O ceramics; it is based on use of molten Ba(OH){sub 2}{center_dot}8H{sub 2}O flux. Two different chemical systems have been examined; the first one, based on nitrate salts, has been demonstrated to be a viable precursor material for tape casting and extrusion; the second, made from acetate salts, has been used for powder synthesis and extrusion. Rheology of pastes shows that their flow may be fit to either Bingham Plastic or Hershel- Bulkley models. Yield stress is controlled in both pastes by volume fraction solids. Viscosity also follows solids loading in the paste. Shear thinning is controlled by colloidal nature of precursor. The paste has colloidal microstructure. Comparison of concentric cylinder rheometry and piston extrusion rheometry shows order of magnitude differences in yield stress, resulting from the test method and paste dilation.
Synthesis, rheology and forming of Y-Ba-Cu-O ceramics
International Nuclear Information System (INIS)
A chemical synthesis route is discussed which results in a low- temperature precursor to Y-Ba-Cu-O ceramics; it is based on use of molten Ba(OH)2�8H2O flux. Two different chemical systems have been examined; the first one, based on nitrate salts, has been demonstrated to be a viable precursor material for tape casting and extrusion; the second, made from acetate salts, has been used for powder synthesis and extrusion. Rheology of pastes shows that their flow may be fit to either Bingham Plastic or Hershel- Bulkley models. Yield stress is controlled in both pastes by volume fraction solids. Viscosity also follows solids loading in the paste. Shear thinning is controlled by colloidal nature of precursor. The paste has colloidal microstructure. Comparison of concentric cylinder rheometry and piston extrusion rheometry shows order of magnitude differences in yield stress, resulting from the test method and paste dilation
Synthesis of a Magneto-Rheological vehicle suspension system built on the variable structure control approach
Scientific Electronic Library Online (English)
Leonardo Tavares, Stutz; Fernando Alves, Rochinha.
Full Text Available The synthesis of a magneto-rheological vehicle suspension system built on the variable structure control approach is considered in the present work. The suspension is synthesized in order to improve the ride comfort obtained by a standard passive suspension. Although a nominal half-vehicle model wit [...] h rigid body is considered in the synthesis of the suspension, phenomenological models for the MR dampers and for the seat-driver subsystem, along with the flexibility of the vehicle body, are considered in the performance assessment. For comparison purposes, active and magneto-rheological suspensions built on the optimal control approach and an active suspension built on the variable structure control approach are also considered. The numerical results show that the proposed suspension outperforms the passive suspension and presents a performance comparable to that of the active ones when the vehicle body may be assumed as rigid. Besides, when its flexibility is an important issue, a great performance drop may be observed, depending on the road quality, the damper characteristics and the adopted control strategy.
Synthesis and electrochemical study of polymer-electrolyte for high energetic density accumulator.
Czech Academy of Sciences Publication Activity Database
Kerouani, N.; Vondr�k, Ji?�
Vol. 1. Brno : Akademick� nakladatelstv� CERM, 2000 - (Vondr�k, J.; Sedla?�kov�, M.), s. 4.1-4.6 ISBN 80-214-1614-9. [Advanced Batteries and Accumulators /1./. Brno (CZ), 28.08.2000-01.09.2000] Institutional research plan: CEZ:AV0Z4032918 Keywords : synthesis * polymer-electrolyte * electrochemistry Subject RIV: CG - Electrochemistry
Synthesis of Single Phase Hg-1223 High Tc Superconducting Films With Multistep Electrolytic Process
Shivagan, D. D.; Shirage, P M; Ekal, L. A.; Pawar, S.H.
We report the multistep electrolytic process for the synthesis of high Tc single phase HgBa2Ca2Cu3O8+? (Hg-1223) superconducting films. The process includes : i) deposition of BaCaCu precursor alloy, ii) oxidation of BaCaCu films, iii) electrolytic intercalation of Hg in precursor BaCaCuO films and iv) electrochemical oxidation and annealing of Hg-intercalated BaCaCuO films to convert into Hg1Ba2Ca2Cu3O8+? (Hg-1223). Films were characterized by thermo-gravimetr...
Solvothermal synthesis of gallium-indium-zinc-oxide nanoparticles for electrolyte-gated transistors.
Santos, L�dia; Nunes, Daniela; Calmeiro, Tom�s; Branquinho, Rita; Salgueiro, Daniela; Barquinha, Pedro; Pereira, Lu�s; Martins, Rodrigo; Fortunato, Elvira
Solution-processed field-effect transistors are strategic building blocks when considering low-cost sustainable flexible electronics. Nevertheless, some challenges (e.g., processing temperature, reliability, reproducibility in large areas, and cost effectiveness) are requirements that must be surpassed in order to achieve high-performance transistors. The present work reports electrolyte-gated transistors using as channel layer gallium-indium-zinc-oxide nanoparticles produced by solvothermal synthesis combined with a solid-state electrolyte based on aqueous dispersions of vinyl acetate stabilized with cellulose derivatives, acrylic acid ester in styrene and lithium perchlorate. The devices fabricated using this approach display a ION/IOFF up to 1 � 10(6), threshold voltage (VTh) of 0.3-1.9 V, and mobility up to 1 cm(2)/(V s), as a function of gallium-indium-zinc-oxide ink formulation and two different annealing temperatures. These results validates the usage of electrolyte-gated transistors as a viable and promising alternative for nanoparticle based semiconductor devices as the electrolyte improves the interface and promotes a more efficient step coverage of the channel layer, reducing the operating voltage when compared with conventional dielectrics gating. Moreover, it is shown that by controlling the applied gate potential, the operation mechanism of the electrolyte-gated transistors can be modified from electric double layer to electrochemical doping. PMID:25517251
Synthesis and thermal behaviour of an amorphous solid polymer electrolyte
Barbosa, P. C.; Rodrigues, L.C.; Silva, Maria Manuela; Smith, Michael John; Costa, Marta S�lvia Freitas da
In this study the synthesis of an amorphous polymer network, poly[oxymethylene-oligo(oxyethylene)], designated as aPEO, is described. This polymer has been characterized by gel permeation chromatography, thermal analysis, conductivity measurements, evaluation of electrochemical stability and nuclear magnetic resonance spectroscopy. The synthetic procedure developed permits partial fractionation of the product of the polymerization reaction. This linear macromolecule appears to be a promising ...
Hot-pressed Ag+ Ion Conducting Glass-Polymer Electrolytes: Synthesis and Battery Application
Scientific Electronic Library Online (English)
Angesh, Chandra.
Full Text Available Synthesis of new Ag+ ion conducting glass-polymer electrolytes (GPEs): (1-x) PEO: x [0.75(0.75AgI:0.25AgCl):0.25(Ag2O:P2O5)], where 0 [...] )], with conductivity (?) ? 6.0 � 10-6 S cm-1, was identified from the compositional dependent conductivity studies and this has been referred to as the Optimum Conducting Composition (OCC). Approximately three orders of conductivity enhancement have been achieved in GPE OCC from that of the pure polymer PEO. The glass-polymer complexation has been confirmed by SEM and DSC analysis. Ion transport parameters viz. ionic conductivity (?), ionic mobility (?), mobile ion concentration (n) and ionic transference number (tion) have been characterized using different experimental techniques. Solid-state polymeric batteries were fabricated using GPE OCC as electrolyte and the cell-potential discharge characteristics were studied under different load conditions at room temperature.
Synthesis of Single Phase Hg-1223 High Tc Superconducting Films With Multistep Electrolytic Process
Shivagan, D D; Ekal, L A; Pawar, S H
We report the multistep electrolytic process for the synthesis of high Tc single phase HgBa2Ca2Cu3O8+? (Hg-1223) superconducting films. The process includes : i) deposition of BaCaCu precursor alloy, ii) oxidation of BaCaCu films, iii) electrolytic intercalation of Hg in precursor BaCaCuO films and iv) electrochemical oxidation and annealing of Hg-intercalated BaCaCuO films to convert into Hg1Ba2Ca2Cu3O8+? (Hg-1223). Films were characterized by thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrolytic intercalation of Hg in BaCaCuO precursor is proved to be a novel alternative to high temperature-high pressure mercuration process. The films are single phase Hg-1223 with Tc = 121.5 K and Jc = 4.3 x 104 A/cm2.
Design and synthesis of new electrolyte systems for lithium-ion batteries
Chakrabarti, Amartya
Rechargeable lithium-ion batteries are extensively used in consumer electronic products, including laptop computers, cellular phones, cameras, camcorders, and medical devices. They have great potential for application in electric and hybrid electric vehicles by virtue of their high energy and power density. Research and development in this direction have been focused all around the globe. The major challenges include the higher cost, safety issues related to the solvents, and conductivities at lower ambient temperature of the solvent-free solid polymer electrolyte (SPE) systems. In this dissertation, three different approaches are presented to achieve an improved electrolyte system for lithium-ion batteries. A plasticizer was synthesized and incorporated into a conventional poly(ethylene oxide) (PEO)-based solid polymer electrolyte system. The ambient temperature ionic conductivity observed at room temperature was noteworthy, due to the decrease of the glass transition temperature of the polymer. Secondly, a branched polymer was synthesized and used as the base matrix in SPEs. Polymers with a higher order of branching remained undissolved in common organic solvents, thereby limiting the scope of their use for making films for the study. The ones with a lower order of branching exhibited ionic conductivities comparable to regular PEO-based electrolytes. The third and most successful approach involved the strategic design and synthesis of a series of low lattice energy lithium salts and their chemical, thermal and electrochemical characterization. In this methodology, the two-to-three step synthetic strategy involved chlorosulfonation of an activated aromatic ring, reaction of the corresponding sulfonyl chloride with trifluoromethanesulfonamide in the presence of triethylamine as a base, followed by lithiation of the resulting triethylammonium salt to generate monolithium, dilithium and scaffolded polylithium salts. The mono- and dilithium salts were tested in electrolyte systems for SPEs, whereas the polylithium salts were characterized as potential candidates for liquid electrolyte systems. The tri-lithium salt based on triptycene proved to be the best of the lot. While all of them showed excellent thermal and electrochemical stability, the salt based on triptycene also demonstrated very good ambient temperature conductivity at low concentrations. The cycling characteristics observed, as well as lithium ion transference number measured with this salt, were impressive and equal to or exceed those for the currently best salt, lithium trifluromethanesulfonimide (LiTFSI).
Synthesis of nanospherical Fe3BO6 anode material for lithium-ion battery by the rheological phase reaction method
International Nuclear Information System (INIS)
This paper developed a novel method, the rheological phase reaction method, to synthesize nanospherical Fe3BO6. The sizes and morphologies of products vary with the calcination temperatures. Spherical particles with a uniform size about 40 nm in a monodisperse state were obtained at 800 deg. C, while the spherical particles with a larger size of 100-500 nm were obtained at 900 deg. C. The electrochemical properties of these Fe3BO6 nanospheres were investigated. Sample synthesized at 800 deg. C delivers a high reversible capacity above 500 mAh g-1. Sample synthesized at 900 deg. C possesses relatively good cycleability with a capacity retaining of 376 mAh g-1 after 10 cycles. The measurement of electrochemical impedance spectra for the first time indicated that smaller Fe3BO6 nanoparticles intend to give higher impedance of solid-electrolyte interface layer and lower charge-transfer impedance after the first discharge. Additionally, it can be speculated that the increase of resistance charge-transfer is the possible reason for the capacity fading during cycling. - Graphical abstract: Nanospherical Fe3BO6 anode material for lithium-ion battery has been synthesized by the rheological phase reaction method. The electrochemical properties of these Fe3BO6 nanospheres show that sample synthesized at 800 deg. C delivers a high reversible capacitydeg. C delivers a high reversible capacity above 500 mAh g-1, and sample synthesized at 900 deg. C possesses relatively good cycleability with a capacity retaining of 376 mAh g-1 after 10 cycles
RHEOLOGICAL PHASE SYNTHESIS AND CHARACTERIZATION OF MICRO-SIZED Li4Ti5O12
Scientific Electronic Library Online (English)
Full Text Available Zero-strain anode material of Li4Ti5O12 for lithium ion battery was successfully synthesized via the rheological phase reaction (RPR) method. The as-prepared powders were characterized by means of powder X-ray diffraction (XRD), scanning electron microscope (SEM) and particle size distribution analy [...] sis (PSD), and the electrochemical properties of the powders were evaluated by the galvanostatic discharge test and cyclic voltammetry (CV). The results revealed that well-crystallized uniform micro-sized Li4Ti5O12 powders were obtained at 800�C for different calcination times via the simple template-free rheological phase route. Among these RPR-derived Li4Ti5O12 powders, one synthesized at 800�C for 22 h displays the initial discharge capacity of 184.3 mAh/g and excellent characteristic of cyclic voltammetry.
RHEOLOGICAL PHASE SYNTHESIS AND CHARACTERIZATION OF MICRO-SIZED Li4Ti5O12
Directory of Open Access Journals (Sweden)
Full Text Available Zero-strain anode material of Li4Ti5O12 for lithium ion battery was successfully synthesized via the rheological phase reaction (RPR method. The as-prepared powders were characterized by means of powder X-ray diffraction (XRD, scanning electron microscope (SEM and particle size distribution analysis (PSD, and the electrochemical properties of the powders were evaluated by the galvanostatic discharge test and cyclic voltammetry (CV. The results revealed that well-crystallized uniform micro-sized Li4Ti5O12 powders were obtained at 800�C for different calcination times via the simple template-free rheological phase route. Among these RPR-derived Li4Ti5O12 powders, one synthesized at 800�C for 22 h displays the initial discharge capacity of 184.3 mAh/g and excellent characteristic of cyclic voltammetry.
Proton-conducting polymer electrolyte membranes based on fluoropolymers incorporating perfluorovinyl ether sulfonic acids and fluoroalkenes Synthesis and characterizations
Souzy, R.; Ameduri, Bruno; Boutevin, Bernard; Capron, P.; Marsacq, D.; Gebel, G.
This paper presents the synthesis of new polymer electrolyte membranes based on fluoropolymers incorporating aromatic perfluorovinyl ether sulfonic acids. A novel synthetic route describing the preparation of perfluorovinyl ether monomer containing sulfonic functionalities, 4-[(alpha,beta,beta-trifluorovinyl)oxy]benzene sulfonic acid (TFVOBSA), is reported. The radical (co) and terpolymerization of 4-[(alpha,beta,beta-trifluorovinyl)oxy]benzene sulfonyl chloride (TFVOBSC) with 1,1-difluoroeth...
Synthesis and ceramic processing of zirconia alumina composites for application as solid oxide fuel cell electrolytes
International Nuclear Information System (INIS)
The global warmness and the necessity to obtain clean energy from alternative methods than petroleum raises the importance of developing cleaner and more efficient systems of energy generation, among then, the solid oxide fuel cell (SOFC). Cubic stabilized zirconia (CSZ) has been the most studied material as electrolyte in SOFC, due to its ionic conductivity and great stability at operation conditions. However, its low fracture toughness difficulties its application as a thin layer, what could lead to an improvement of cell efficiency. In this sense, the alumina addition in CSZ forms a composite, which can shift its mechanical properties, without compromising its electrical properties. In this work, coprecipitation synthesis route and ceramic processing of zirconia-alumina composites were studied, in order to establish optimum conditions to attain high density, homogeneous microstructure, and better mechanical properties than CSZ, without compromising ionic conductivity. For this purpose, composites containing up to 40 wt % of alumina, in a 9 mol % yttria-stabilized zirconia (9Y-CSZ) matrix were evaluated. In order to optimize the synthesis of the composites, a preliminary study of powder obtaining and processing were carried out, at compositions containing 20 wt % of alumina, in 9Y-CSZ. The ceramic powders were characterized by helium picnometry, X-ray diffraction, scanning electronic microscopy, transmission electronic microscopy, thermogravimetry, differential scanning calorimetry, granulometry by laser diffraction and gas adsorption (BET). The characterization of sinterized compacts were performed by X-ray diffraction, scanning electron microscopy, optical microscopy, density measurements, Vickers indentation and impedance spectroscopy. The obtained results show that the alumina addition, in the 9Y-CSZ matrix powders, raises the specific surface area, promotes deagglomeration of powders and elevates the oxides crystallization temperature, requiring higher energetic thermal treatments to attain high densities. In relation to the sintered products, it was confirmed the excellent homogeneity and crystallinity of microstructure provided by the chosen route, the restriction of grain growth by alumina addition, raise of hardness and fracture toughness, and higher ionic conductivity, even tough a lower bulk conductivity. These results indicate that the addition of 5 wt % alumina in CSZ matrix allows the application of this material as solid oxide fuel cell electrolytes, due to its better fracture toughness and ionic conductivity, compared to yttria-stabilized cubic zirconia ceramics. (author)
Synthesis of carbon-supported titanium oxynitride nanoparticles as cathode catalyst for polymer electrolyte fuel cells
International Nuclear Information System (INIS)
Highlights: � A sol�gel route for the synthesis of rutile TiO2 was modified to synthesize TiOxNy-C. � N atoms were doped into TiOx nanoparticles solely by the heat-treatment under N2 gas. � The N2-treatment produced sites more active toward ORR compared with NH3-treatment. � TiOx doped with a small amount of N atoms are suggested to be responsible for ORR. -- Abstract: For use as the oxygen reduction reaction (ORR) catalyst in polymer electrolyte fuel cell cathodes, carbon-supported titanium oxynitride (TiOxNy-C) nanoparticles with a size of approximately 5 nm or less were synthesized without using NH3 gas. A sol�gel route developed for the synthesis of pure rutile TiO2 nanopowders was modified to prepare the carbon-supported titanium oxide nanoparticles (TiOx-C). For the first time, N atoms were doped into TiOx solely by heating TiOx-C under an inexpensive N2 atmosphere at 873 K for 3 h, which could be due to carbothermal reduction. The TiOx-C powder was also heated under NH3 gas at various temperatures (873�1273 K) and durations (3�30 h). This step resulted in the formation of a TiN phase irrespective of the heating conditions. Both N2- and NH3-treated TiOxNy-C did not crystallize well; however, the former showed a mass activity more than three times larger than that of the latter at 0.74 V versus the standard hydrogen electrode. Thus, titanium oxide nanoparticles doped with a small amount of N atoms are suggested to be responsible for catalyzing ORR in the case of N2-treated TiOxNy-C
Some observations on synthesis and electrolytic properties of nonstoichiometric calcium zirconate
International Nuclear Information System (INIS)
Stoichiometric CaZrO3 (CZ-50) and CaZrO3 doped with excess CaO (CZ-51) powders, whose formula (CaO)1-x(ZrO2)x, where x = 50 or 51 mol.% CaO was successfully synthesised by the co-precipitation calcination method with a saturated solution of (NH4)2C2O4 in concentrated NH3 solution as a precipitation agent. The thermal evolution of CaZrO3 dried precursor during heating them up to 1200 deg. C was monitored by thermal (DTA, TG) and X-ray diffraction analysis methods. The highest temperature (1200 deg. C) for CaZrO3 synthesis was found for stoichiometric CaZrO3, whereas introduction of excess CaO into CaZrO3 led to a decrease in the synthesis temperature to 1000 deg. C. The crystallite size d(hkl) of grounded CaZrO3 powders ranged from ?43 to ?90 nm, respectively. BET measurements indicated that in both the investigated powders, particles were agglomerated. Sintering CaZrO3-based samples at 1500 deg. C/2 h or hot-pressing process (1250 deg. C/1 h, 25 MPa) was applied to obtain gas-tight CaZrO3-based ceramics. To examine the thermochemical stability of materials obtained at high temperatures, the CaZrO3-based samples were additionally heated at 1200 deg. C for 120 h or in the temperature range 1400-1600 deg. C for 24 h in air or purified argon. There were also perfr purified argon. There were also performed and then discussed, some tests on thermal resistance of CaZrO3 against molten metals-nickel and copper. Investigations into chemical reactivity of CaZrO3 electrolyte with electrode materials involving LaCrO3 or MCr2O4 (M = Mg, Ca) in the temperature range 1000-1200 deg. C were conducted using XRD with Rietveld analysis. Electrical conductivity measurements performed by both dc and ac impedance spectroscopy method in the temperature range 200-1000 deg. C. The best oxygen ion conductivity was found for CaZrO3-doped excess CaO (CZ-51) samples sintered in air, starting from powders synthesized by co-precipitation or citrate method. The CZ-51 samples obtained via solid state reaction or hot-pressed exhibited lower values of electrical conductivity. Test results for this compound used as an electrolyte in solid oxide cells involving electrode materials MCr2O4 (M = Mg, Ca) are also reported. In this way the Gibbs free energy of formation of MgCr2O4 at 1000 deg. C was determined. The nonstoichiometric CaZrO3 seems to be a promising solid electrolyte for electrochemical oxygen probes in control of metal processing.
Synthesis and characterization of hot pressed ion conducting solid polymer electrolytes: (1 - x) PEO: x NaClO4
Chandra, Angesh; Chandra, Archana; Thakur, Kiran
Synthesis and ion transport characterization of hot-pressed poly(ethylene oxide) PEO-based solid polymer electrolytes (SPEs): (1 - x) PEO: x NaClO4, where 0 conductivity (?) ~ 7.07 � 10-7 S cm-1 shows the highest conducting composition and this have been referred to as optimum conducting composition (OCC). Materials characterization and thermal behavior of the present SPEs have been done with the help of XRD, FTIR, SEM, DSC and TG analysis. To determine the activation energy, temperature dependent ionic conductivity (?) of different compositions has been measured. Ionic nature of the SPEs has been explained with the help of ionic transference number (tion) measurements. Finally, the thin film polymer battery is also fabricated using the SPE OCC as electrolyte and calculated their cell parameters at room temperature.
Synthesis and characterization of nanocrystalline dysprosia stabilized zirconia based electrolyte for intermediate-temperature solid oxide fuel cell
International Nuclear Information System (INIS)
The present work concerns studies on synthesis (by chemical co-precipitation) and characterization (microstructural and electrical) of 8 and 10 mol% dysprosia stabilized nanocrystalline cubic-zirconia (DySZ) for use as electrolyte materials in solid oxide fuel cell in the intermediate temperature range. Identity and crystallite size of the calcined powders were determined by X-ray diffraction. Microstructural studies of calcined/sintered product by transmission and scanning electron microscopes allowed verification of crystallite/particle size and analysis of morphology/density/distribution of the defects, respectively. Impedance spectroscopy revealed that the contribution of grain boundary resistance is higher than that of the bulk. Furthermore, conductivity analysis evidenced an Arrhenius type thermally activated ionic conduction above 300 deg. C. Thus, DySZ appears a possible alternative to yttria stabilized zirconia (YSZ) as electrolyte for solid oxide fuel cells due to its lower thermal and comparable ionic conductivity as YSZ.
Synthesis, morphology and rheology of core-shell silicone acrylic emulsion stabilized with polymerisable surfactant
Directory of Open Access Journals (Sweden)
Full Text Available Core-shell silicone acrylic emulsions with 3-methacryloxypropyl trimethoxysilane (MPTS in the shell were prepared by seeded polymerization with the assistance of polymerisable maleate surfactant (MT. Fourier transform infrared (FT-IR demonstrated the incorporation of polymerisable surfactant in copolymer. It was found that small amount of octadecyl acrylate was beneficial to emulsion stability with decreasing the particle size from 194.6 to 165.7 nm. It was also found that the particle size increased from 165.7 to 242.9 nm with the increase of MPTS concentration. Furthermore, rheological measurement indicated that the emulsion was endowed with pseudoplasticity. At low shear rate, marginal reduction in viscosity was detected when MPTS concentration increased to 2%, while great increase in viscosity was observed with higher MPTS concentration, the interaction force among emulsion particles became the predominant factor instead of particle size. In addition, better water resistance was observed when MT concentration was lower than 1.5%, and MPTS concentration higher than 2%. Moreover, surface roughness was increased with MPTS addition, the crosslinking among core and shell reconstructed the surface morphology of film.
Synthesis and Rheological Properties of an Associative Star Polymer in Aqueous Solutions
DEFF Research Database (Denmark)
Hietala, Sami; Mononen, Pekka
Rheological properties of aqueous solutions and hydrogels fonned by an amphiphiIic star block copolymer poly(acrylic acid)-blockpolystyrene (PAAS4-b-PS6)4. were investigated as a function of the polymer concentration (Cp), temperature, and added saIt concentration. The water-soluble polymer synthesised by atom transfer radical. polymerization (ATRP) was found to fonn hydrogels at room temperature at polymer concentrations. Cp, over 22 gIL due to the interpolymer drophobic association of the PS blocks. Increasing Cp leads to stronger elastic networks at room temperature that show a gel-to-solution transition with increasing temperature. Increase of ionic strength decreases the moduli compared with the pure hydrogel but did not affect the gel-sol transition temperature significantly. Small-angle X-ray experiments showed two distinct scattering correlation peaks for samples above the gelling Cp, which indicates the aggregates fonmed due to hydrophobic association. Upon heating the intensity of the scattering correlation peaks was found to decrease indicating the loss of the network structure due to thermal motion.
Synthesis and investigation of electrolytic sodium-vanadium oxide compounds for cathodes of lithium batteries: the production of compounds with stable initial characteristics
International Nuclear Information System (INIS)
Heterogeneous vanadium oxide compounds were prepared during electrolysis of vanadyl sulfate solution in the presence of sodium ions. The limits of process parameters for synthesis of electrolysis products with stable initial electrochemical characteristics were ascertained. It is shown that the presence of sodium ions gives rise to the deposit adhesion o substrate. Electrochemical properties of the electrolytic deposits depend on the content of sodium ions in deposition electrolyte and subsequent thermal treatment of the deposit. Specific discharge capacity of electrolytic Na-vanadium oxide compounds may reach 320 Ah/kg in case of discharge up to 2.0 V at a density of 100 ?A/cm2
Synthesis, ionic conductivity, and thermal properties of proton conducting polymer electrolyte for high temperature fuel cell
Energy Technology Data Exchange (ETDEWEB)
Itoh, Takahito; Hamaguchi, Yohei; Uno, Takahiro; Kubo, Masataka [Department of Chemistry for Materials, Faculty of Engineering, Mie University, 1577 Kurima Machiya-cho, Tsu, Mie 514-8507 (Japan); Aihara, Yuichi; Sonai, Atsuo [Samsung Yokohama Research Institute, 2-7 Sugasawa-cho, Tsurumi-ku, Yokohama 230-0027 (Japan)
Hyperbranched polymer (poly-1a) with sulfonic acid groups at the end of chains was successfully synthesized. Interpenetration reaction of poly-1a with a hyperbranched polymer with acryloyl groups at the end of chains (poly-1b) as a cross-linker afforded a tough electrolyte membrane. The poly-1a and the resulting electrolyte membrane showed the ionic conductivities of 7x10{sup -4} and 8x10{sup -5} S/cm, respectively, at 150C under dry condition. The ionic conductivities of the poly-1a and the electrolyte membrane exhibited the VTF type temperature dependence. And also, both poly-1a and the resulting electrolyte membrane were thermally stable up to 200C. (author)
Synthesis and electrochemical characterization of PEO-based polymer electrolytes with room temperature ionic liquids
International Nuclear Information System (INIS)
New gel polymer electrolytes containing 1-butyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide (BMPyTFSI) ionic liquid are prepared by solution casting method. Thermal and electrochemical properties have been determined for these gel polymer electrolytes. The addition of BMPyTFSI to the P(EO)20LiTFSI electrolyte results in an increase of the ionic conductivity, and at high BMPyTFSI concentration (BMPy+/Li+ = 1.0), the ionic conductivity reaches the value of 6.9 x 10-4 S/cm at 40 oC. The lithium ion transference numbers obtained from polarization measurements at 40 oC were found to decrease as the amount of BMPyTFSI increased. However, the lithium ionic conductivity increased with the content of BMPyTFSI. The electrochemical stability and interfacial stability for these gel polymer electrolytes were significantly improved due to the incorporation of BMPyTFSI
Synthesis and electrochemical characterization of PEO-based polymer electrolytes with room temperature ionic liquids
Energy Technology Data Exchange (ETDEWEB)
Cheng, Hu; Zhu, Changbao; Huang, Bin; Lu, Mi; Yang, Yong [State Key Laboratory for Physical Chemistry of Solid Surface, Department of Chemistry, Xiamen University, Xiamen 361005 (China)
New gel polymer electrolytes containing 1-butyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide (BMPyTFSI) ionic liquid are prepared by solution casting method. Thermal and electrochemical properties have been determined for these gel polymer electrolytes. The addition of BMPyTFSI to the P(EO){sub 20}LiTFSI electrolyte results in an increase of the ionic conductivity, and at high BMPyTFSI concentration (BMPy{sup +}/Li{sup +} = 1.0), the ionic conductivity reaches the value of 6.9 x 10{sup -4} S/cm at 40 C. The lithium ion transference numbers obtained from polarization measurements at 40 C were found to decrease as the amount of BMPyTFSI increased. However, the lithium ionic conductivity increased with the content of BMPyTFSI. The electrochemical stability and interfacial stability for these gel polymer electrolytes were significantly improved due to the incorporation of BMPyTFSI. (author)
Synthesis of a novel imidazolium-based electrolytes and application for dye-sensitized solar cells
International Nuclear Information System (INIS)
A series of new imidazolium-based oligomers with different length of a poly(ethylene glycol) moiety as a linker were synthesized and studied as electrolytes for dye-sensitized solar cell (DSSC). These oligomeric molecules are expected to have an intra- or inter-molecular hydrogen bonding interaction through its urethane and urea bonds. They can be used to prepare the liquid-type electrolytes for DSSC by dissolving them into conventional solvent system or to develop solvent-free electrolytes by incorporating an extra redox mediator and other functional materials together as additives. It was found that these oligomers could replace the cationic component of the conventional electrolytes and became the source of redox species when iodine is added. The photocurrent-voltage characteristics of DSSCs with the electrolytes containing these oligomers demonstrated that they can successfully replace the conventional ionic liquid-type electrolytes such as 1-methyl-3-propyl imidazolium iodide (PMII) in 3-methoxypropionitrile (MPN) if the length of the linker is optimized.
Synthesis of a novel imidazolium-based electrolytes and application for dye-sensitized solar cells
Energy Technology Data Exchange (ETDEWEB)
Seo, Dong-Wan [Department of Applied Chemistry, Konkuk University, 322 Danwol-dong, 380-701 Chungju (Korea, Republic of); Sarker, Subrata; Nath, Narayan Chandra Deb [Department of Advanced Technology Fusion, Konkuk University, Seoul (Korea, Republic of); Choi, Seung-Woo [Department of Applied Chemistry, Konkuk University, 322 Danwol-dong, 380-701 Chungju (Korea, Republic of); Ahammad, A.J. Saleh [Department of Advanced Technology Fusion, Konkuk University, Seoul (Korea, Republic of); Lee, Jae-Joon, E-mail: email@example.com [Department of Applied Chemistry, Konkuk University, 322 Danwol-dong, 380-701 Chungju (Korea, Republic of); Department of Advanced Technology Fusion, Konkuk University, Seoul (Korea, Republic of); Kim, Whan-Gi, E-mail: email@example.com [Department of Applied Chemistry, Konkuk University, 322 Danwol-dong, 380-701 Chungju (Korea, Republic of)
A series of new imidazolium-based oligomers with different length of a poly(ethylene glycol) moiety as a linker were synthesized and studied as electrolytes for dye-sensitized solar cell (DSSC). These oligomeric molecules are expected to have an intra- or inter-molecular hydrogen bonding interaction through its urethane and urea bonds. They can be used to prepare the liquid-type electrolytes for DSSC by dissolving them into conventional solvent system or to develop solvent-free electrolytes by incorporating an extra redox mediator and other functional materials together as additives. It was found that these oligomers could replace the cationic component of the conventional electrolytes and became the source of redox species when iodine is added. The photocurrent-voltage characteristics of DSSCs with the electrolytes containing these oligomers demonstrated that they can successfully replace the conventional ionic liquid-type electrolytes such as 1-methyl-3-propyl imidazolium iodide (PMII) in 3-methoxypropionitrile (MPN) if the length of the linker is optimized.
Molecular rheology of branched polymers: decoding and exploring the role of architectural dispersity through a synergy of anionic synthesis, interaction chromatography, rheometry and modeling.
van Ruymbeke, E; Lee, H; Chang, T; Nikopoulou, A; Hadjichristidis, N; Snijkers, F; Vlassopoulos, D
An emerging challenge in polymer physics is the quantitative understanding of the influence of a macromolecular architecture (i.e., branching) on the rheological response of entangled complex polymers. Recent investigations of the rheology of well-defined architecturally complex polymers have determined the composition in the molecular structure and identified the role of side-products in the measured samples. The combination of different characterization techniques, experimental and/or theoretical, represents the current state-of-the-art. Here we review this interdisciplinary approach to molecular rheology of complex polymers, and show the importance of confronting these different tools for ensuring an accurate characterization of a given polymeric sample. We use statistical tools in order to relate the information available from the synthesis protocols of a sample and its experimental molar mass distribution (typically obtained from size exclusion chromatography), and hence obtain precise information about its structural composition, i.e. enhance the existing sensitivity limit. We critically discuss the use of linear rheology as a reliable quantitative characterization tool, along with the recently developed temperature gradient interaction chromatography. The latter, which has emerged as an indispensable characterization tool for branched architectures, offers unprecedented sensitivity in detecting the presence of different molecular structures in a sample. Combining these techniques is imperative in order to quantify the molecular composition of a polymer and its consequences on the macroscopic properties. We validate this approach by means of a new model asymmetric comb polymer which was synthesized anionically. It was thoroughly characterized and its rheology was carefully analyzed. The main result is that the rheological signal reveals fine molecular details, which must be taken into account to fully elucidate the viscoelastic response of entangled branched polymers. It is important to appreciate that, even optimal model systems, i.e., those synthesized with high-vacuum anionic methods, need thorough characterization via a combination of techniques. Besides helping to improve synthetic techniques, this methodology will be significant in fine-tuning mesoscopic tube-based models and addressing outstanding issues such as the quantitative description of the constraint release mechanism. PMID:24705637
Synthesis of Bi2WO6 nanoparticles and its electrochemical properties in different electrolytes for pseudocapacitor electrodes
International Nuclear Information System (INIS)
Highlights: � A simple, economical and environmentally benign sonochemical technique was utilized for the synthesis of homogeneous Bi2WO6 nanoparticles. � This is the first attempt to employ Bi2WO6 as a supercapacitor electrode material. � Effect of electrolyte on the capacitive behaviour of the material is studied. � Bi2WO6 displays good capacitive behaviour in 1 M KOH compared with 1 M NaOH and 1 M LiOH and possess sufficient capacity retention. � It presented an energy density of 67 Wh/kg in the potential range from ?0.9 V to 0.1 V and it would be a promising negative electrode for supercapacitor. -- Abstract: Nanosized Bi2WO6 particles were successfully synthesized by sonochemical method with an objective to develop an inexpensive and eco-friendly electrode material for supercapacitors. The prepared material was subjected to various thermal, structural, morphological, compositional, electrical and electrochemical studies. Bi2WO6 nanoparticle with homogeneous distribution was achieved through sonochemical process. The lattice parameter and atomic positions of Bi2WO6 structure were refined through Reitveld analysis. The electrochemical performance of Bi2WO6 nanoparticles was investigated in various aqueous electrolytes such as 1 M NaOH, 1 M LiOH, 1 M Na2SO4, 1 M KOH and 6 M KOH solutions. Among these, the material exhibited an enhanced electrochemical performance in KOH electrolyte due to its smaller hydration sphere radius, high ionic mobility and lower equivalent series resistance. The charge�discharge studies rendered a specific capacitance of 608 F/g in 1 M KOH at a current density of 0.5 mA/cm2. Bi2WO6 exhibited an excellent coulombic efficiency and specific capacitance of around 304 F/g at 3 mA/cm2 in the potential range from ?0.9 to 0.1 V vs Hg/HgO in 1 M KOH electrolyte. The above results assured that Bi2WO6 could be utilized as suitable negative electrode material for supercapacitor applications and 1 M KOH could be its desirable electrolyte
Owens, RG
Modern day high-performance computers are making available to 21st-century scientists solutions to rheological flow problems of ever-increasing complexity. Computational rheology is a fast-moving subject - problems which only 10 years ago were intractable, such as 3D transient flows of polymeric liquids, non-isothermal non-Newtonian flows or flows of highly elastic liquids through complex geometries, are now being tackled owing to the availability of parallel computers, adaptive methods and advances in constitutive modelling.Computational Rheology traces the development of numerical methods fo
Studies on synthesis and characterizations of gadolinium doped ceria as solid electrolyte
International Nuclear Information System (INIS)
Due to need of pollution-free and efficient-power-generation devices, in past few years, pace of research has been rapidly driven by fuel cell technology. The thesis contributes in the same regard, in which conventional solid electrolyte of solid oxide fuel cell is replaced by alternate material (Gd-doped-Ceria-GDC) and its performance has been tested. The process parameters of ceramic route and spray-pyrolysis-technique were optimized to obtain dense 'electrolyte-grade' GDC-bulk and thin-film samples, respectively. In symmetrical cell configuration, GDC-bulk sample showed open-circuit-voltage of 0.84 volts at 500 deg C. The grain interior conductivity of 13 ?m GDC-film deposited onto electrode-grade NiO-GDC substrate is ?0.1S/cm at 500 deg C. (author)
Iodide-conducting polymer electrolytes based on poly-ethylene glycol and MgI2: Synthesis and structural characterization
International Nuclear Information System (INIS)
A major obstacle for a viable technological development of dye sensitized solar cells (DSSCs) is still the synthesis of a high performance iodide-conducting polymer electrolyte. Here we present a series of eight electrolytic complexes with formula PEG1000/(MgI2)x(I2)y (0.0038 ? x ? 0.5801, 0 ? y ? 0.0636). The synthesis involves the preparation of a disordered form of MgI2 by a metallorganic route, which enables us to dissolve high amounts of salt in the chosen polymer host. The thermal analysis of the resulting polymer electrolytes was performed using modulated differential scanning calorimetry measurements. Vibrational studies were carried out using medium FT-IR, far FT-IR and FT-Raman. The variation of the CO and OH stretching modes in the medium infrared, as a function of the mole-to-mole ratio nMg/nO, was investigated by Gaussian decomposition to provide insight into the polymer�polymer and salt�polymer interactions in these materials. The FT-Raman spectra confirmed and complemented the vibrational assignment. The conductivity study of these systems was performed by electrical spectroscopy in the frequency interval 10 mHz�10 MHz. The direct current conductivity (?DC) profiles versus the reciprocal temperature exhibited a V�gel-Tamman-F�lcher (VTF) behavior. The best ?DC at 50 �C was 5 � 10?5 S cm?1. The overall results i overall results indicate the presence of bivalent, monovalent and neutral species, Mg2+, [MgI]+ and MgI2, respectively, which participate in the conduction process. These results are consistent with what was previously observed in PEG400-based systems doped with ?-MgCl2. The presence of at least one Mg site containing a distribution in parameters was observed using 25Mg solid state magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. The site has been assigned to a Mg complex involving the coordination by oxygen atoms of the polymer backbone.
Synthesis of Coral-Like Tantalum Oxide Films via Anodization in Mixed Organic-Inorganic Electrolytes
Yu, Hongbin; Zhu, Suiyi; Yang, Xia; Wang, Xinhong; Hongwei SUN; Huo, Mingxin
We report a simple method to fabricate nano-porous tantalum oxide films via anodization with Ta foils as the anode at room temperature. A mixture of ethylene glycol, phosphoric acid, NH4F and H2O was used as the electrolyte where the nano-porous tantalum oxide could be synthesized by anodizing a tantalum foil for 1 h at 20 V in a two�electrode configuration. The as-prepared porous film exhibited a continuous, uniform and coral-like morphology. The diameters of pores ranged from 30 nm to 50 ...
The Synthesis and Evaluation of Proton Conducting Electrolytes for High Temperature Steam Electrolysers
Stuart, Paul Anthony
Proton conducting ceramics based on acceptor doped perovskites are the subject of investigation as candidate electrolyte materials for Solid Oxide Electrolyser Cells (SOECs). Specifically, BaCe0.9Y0.1O3-[delta](BCY10) and BaZr0.9Y0.1O3-[delta](BZY10) were investigated. Samples with greater than 95% of the maximum theoretical density were successfully prepared using a BCY10 commercial powder. It was found that when small additions of ZnO were added to a BZY10 commercial powder, ...
Synthesis, characterization and influence of electrolyte solutions on electrical properties of organic-inorganic composite membrane
Ishrat, Urfi; Rafiuddin
In this work various electrical properties of titanium molybdate composite membrane had been discussed. The membrane was characterized by X-ray diffraction, scanning electron microscopy, particle size analysis and Infra-red spectroscopy. The effective fixed charge density of the membrane was determined by TMS method and it showed the dependence of membrane potential on, the charge on the membrane matrix, porosity and size of permeating ions. The change in membrane capacitance and resistance values with the change in electrolyte concentration and applied frequency had been interpreted in terms of the charges produced in the electrical double layer at the membrane solution interface. The magnitude of membrane capacitance had been found to be dependent on the capacitance of the double layer. In higher frequency range the impedance data evaluated on the basis of simple equivalent electrical circuit model and had been found to follow theoretical prediction. Other parameters such as transport number, distribution coefficient and charge effectiveness were also calculated.
Electrochemical synthesis of polypyrrole on ferrous and non-ferrous metals from sweet aqueous electrolytic medium
International Nuclear Information System (INIS)
The electrodeposition of polypyrrole (PPy) on oxidizable metals such as aluminum and iron has been achieved in aqueous medium of saccharin and pyrrole. Scanning electron microscopy and X-ray photoelectron spectroscopy analysis reveal a good homogeneity of the obtained PPy film. The electrochemical synthesis of PPy coating has been achieved successfully under potentiodynamic, galvanostatic and potentiostatic techniques. The corrosion experiments performed in HCl show that the PPy coating increases the corrosion potential and decreases the corrosion current density
Sol-gel synthesis and characterization of LiNO 3-Al 2O 3 composite solid electrolyte
Sulaiman, Mazdida; Dzulkarnain, N. A.; Rahman, A. A.; Mohamed, N. S.
Composite solid electrolytes in the system (1 - x)LiNO 3- xAl 2O 3, with x = 0.0-0.5 were synthesized by sol-gel method. The synthesis carried out at low temperature resulted in voluminous and fluffy products. The obtained materials were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy/energy dispersive X-ray, Fourier transform infrared spectroscopy and AC impedance spectroscopy. Structural analysis of the samples showed base centred cell type of point lattice of LiNO 3 for the composite samples with x = 0.1-0.2 and body centred cell for the sample with x = 0.3. A trace amount of ?-LiAlO 2 crystal phase was also present in these composite samples. The thermal analysis showed that the samples were in a stable phase between 48 �C and 230-260 �C. Morphological analysis indicated the presence of amorphous phase and particles with sizes ranging from micro to nanometre scale for the composite sample with x = 0.1. The conductivities of the composites were in the order of 10 -3 and 10 -2 S cm -1 at room temperature and 150 �C, respectively.
Synthesis, spectroscopic and electrochemical performance of pasted ?-nickel hydroxide electrode in alkaline electrolyte
Shruthi, B.; Bheema Raju, V.; Madhu, B. J.
?-Nickel hydroxide (?-Ni(OH)2) was successfully synthesized using precipitation method. The structure and property of the ?-Ni(OH)2 were characterized by X-ray diffraction (XRD), Fourier Transform infra-red (FT-IR), Raman spectra and thermal gravimetric-differential thermal analysis (TG-DTA). The results of the FTIR spectroscopy and TG-DTA studies indicate that the ?-Ni(OH)2 contains water molecules and anions. The microstructural and composition studies have been performed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis. A pasted-type electrode is prepared using ?-Ni(OH)2 powder as the active material on a nickel sheet as a current collector. Cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS) studies were performed to evaluate the electrochemical performance of the ?-Ni(OH)2 electrode in 6 M KOH electrolyte. CV curves showed a pair of strong redox peaks as a result of the Faradaic redox reactions of ?-Ni(OH)2. The proton diffusion coefficient (D) for the present ?-Ni(OH)2 electrode material is found to be 1.44 � 10-12 cm2 s-1. Further, electrochemical impedance studies confirmed that the ?-Ni(OH)2 electrode reaction processes are diffusion controlled.
Synthesis, spectroscopic and electrochemical performance of pasted ?-nickel hydroxide electrode in alkaline electrolyte.
Shruthi, B; Bheema Raju, V; Madhu, B J
?-Nickel hydroxide (?-Ni(OH)2) was successfully synthesized using precipitation method. The structure and property of the ?-Ni(OH)2 were characterized by X-ray diffraction (XRD), Fourier Transform infra-red (FT-IR), Raman spectra and thermal gravimetric-differential thermal analysis (TG-DTA). The results of the FTIR spectroscopy and TG-DTA studies indicate that the ?-Ni(OH)2 contains water molecules and anions. The microstructural and composition studies have been performed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis. A pasted-type electrode is prepared using ?-Ni(OH)2 powder as the active material on a nickel sheet as a current collector. Cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS) studies were performed to evaluate the electrochemical performance of the ?-Ni(OH)2 electrode in 6M KOH electrolyte. CV curves showed a pair of strong redox peaks as a result of the Faradaic redox reactions of ?-Ni(OH)2. The proton diffusion coefficient (D) for the present ?-Ni(OH)2 electrode material is found to be 1.44�10(-12) cm(2) s(-1). Further, electrochemical impedance studies confirmed that the ?-Ni(OH)2 electrode reaction processes are diffusion controlled. PMID:25128682
Electrolytic V{sub 2}O{sub 5}: Synthesis, characterization and lithium insertion behavior
Energy Technology Data Exchange (ETDEWEB)
Potiron, E.; Le Galla Salle, A.; Verbaere, A.; Piffard, Y.; Guyomard, D.
Electrolytic V{sub 2}O{sub 5} materials were prepared by electrochemical oxidation of vanadyl ions in aqueous solution. The electrodeposition reaction includes two steps: an oxidation into soluble species followed by a precipitation. With the use of various electrodeposition conditions and subsequent heat treatment it is possible to obtain e-V{sub 2}O{sub 5} compounds with different V{sup IV} and water contents. e-V{sub 2}O{sub 5} compounds are mixed valence, hydrated vanadic acids and their formula can be written as H{sub 0.4}V{sub 2}O{sub 5.2{minus}{delta}}{center_dot}nH{sub 2}O with 0.04 < {delta} < 0.22 and 0 < n < 1.8. These poorly crystallized layered compounds undergo a phase transformation into {alpha}-V{sub 2}O{sub 5} starting at 240 C. The electrochemical intercalation of lithium into these compounds shows two main single phase phenomena at {approx}3.2V/Li and {approx}2.6V/Li. Their capacity retention is better than that of other V{sub 2}O{sub 5} reference compounds, but the reversible capacity down to 2V is only {approx}100Ah/kg at a rate faster than C/5, due to kinetic limitations.
Synthesis of zinc oxide porous structures by anodization with water as an electrolyte
Energy Technology Data Exchange (ETDEWEB)
Shetty, Amitha; Nanda, Karuna Kar [Indian Institute of Science, Materials Research Centre, Bangalore (India)
We report a simple, reliable and one-step method of synthesizing ZnO porous structures at room temperature by anodization of zinc (Zn) sheet with water as an electrolyte and graphite as a counter electrode. We observed that the de-ionized (DI) water used in the experiment is slightly acidic (pH=5.8), which is due to the dissolution of carbon dioxide from the atmosphere forming carbonic acid. Porous ZnO is characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and photoluminescence (PL) studies. The current-transient measurement is carried out using a Gamry Instruments Reference 3000 and the thickness of the deposited films is measured using a Dektak surface profilometer. The PL, Raman and X-ray photoelectron spectroscopy are used to confirm the presence of ZnO phase. We have demonstrated that the hybrid structures of ZnO and poly (3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) exhibit good rectifying characteristics. The evaluated barrier height and the ideality factor are 0.45 eV and 3.6, respectively. (orig.)
Synthesis, processing and characterization of calcia-stabilized zirconia solid electrolytes for oxygen sensing applications
International Nuclear Information System (INIS)
Precursor powders of calcia-stabilized zirconia (CSZ) solid electrolytes have been synthesized by a sol-gel method. The phase evolution of the precursor powders after thermal treatments at different temperatures were analysized by X-ray diffraction technique. Disc-shaped sensor elements were fabricated via uniaxial pressing of the calcined powders and subsequently sintered at 1650 deg. C. Scanning electron microscopy (SEM) was used to analyze the microstructure of the sintered pellets. Platinum electrodes were applied to the sintered elements to produce potentiometric/electrochemical gas sensors. The electrical response of the gas sensors to oxygen and the complex impedance of the sensors in air were measured at various temperatures. Impedance analyses indicate that the sensor cell with 15 mol% CaO has much lower resistance (the sum of bulk and grain-boundary resistance) than the sensor cell with 22 mol% CaO. This is also reflected by the EMF responses of both sensor cells to various oxygen concentrations in the testing gas. The EMF deviation from the theoretical value of the CSZ sensor cell with 22 mol% CaO was larger than that of the CSZ sensor cell with 15 mol% CaO. The corrrelations between material compositions, microstructures of the sintered pellets and the electrical properties of the sensors are discussed
Pilot-scale synthesis and rheological assessment of poly(methyl methacrylate) polymers: perspectives for medical application.
Linan, Lamia Zuniga; Nascimento Lima, N�dson M; Filho, Rubens Maciel; Sabino, Marcos A; Kozlowski, Mark T; Manenti, Flavio
This work presents the rheological assessment of poly(methyl methacrylate) (PMMA) polymers synthesized in a dedicated pilot-scale plant. This material is to be used for the construction of scaffolds via Rapid Prototyping (RP). The polymers were prepared to match the physical and biological properties required for medical applications. Differential Scanning Calorimetry (DSC) and Size Exclusion Chromatography (SEC) measurements verified that the synthesized polymers were atactic, amorphous and linear in chains. Rheological properties such as viscosity, storage and loss modulus, beyond the loss factor, and creep and recovery were measured in a plate-plate sensor within the viscoelastic linear region. The results showed the relevant influence of the molecular weight on the viscosity and elasticity of the material, and how, as the molecular weight increases, the viscoelastic properties are getting closer to those of human bone. This article demonstrates that by using the implemented methodology it is possible to synthesize a polymer, with properties comparable to commercially-available PMMA. PMID:25842114
Self-propagating high-temperature synthesis of La(Sr)Ga(Mg)O3-? for electrolyte of solid oxide fuel cells
International Nuclear Information System (INIS)
This paper describes self-propagating high-temperature synthesis (SHS) of an electrolyte for solid oxide fuel (SOFC), in comparison to a conventional solid-state reaction method (SRM). Doped-lanthanum gallate: La0.9Sr0.1Ga0.8Mg0.2O3-? (LSGM9182) and LSGM9173 as the SOFC electrolyte, was prepared by the SHS and sintered at different temperatures, for measuring the electrical conductivity of the sintered LSGM and the power generating performance at 1073 K, in comparison to the SRM. In the SHS, the LSGM powders with smaller size were obtained and easily sintered at the 100 K-lower temperature, 1673 K, than in the SRM. Most significantly, the electrical conductivity of the sintered LSGM9182 was as high as 0.11 S cm-1 and its maximum power density was a value of 245 mW cm-2 in the cell configuration of Ni/LSGM9182 (0.501 mm in thickness)/Sm0.5Sr0.5CoO3. The conclusion was that the proposed SHS-sintering method with many benefits of minimizing the energy requirement and the processing time in the production, easing temperature restriction for the sintering, and improving the electrolyte performance up to a conventional level is practicable for producing the LSGM-electrolyte of SOFC at an intermediate-temperature application
Synthesis and rheological investigation of a magnetic fluid using olivary silica-coated iron particles as a precursor
Gu, Rui; Gong, Xinglong; Jiang, Wanquan; Hao, Lingyun; Xuan, Shouhu; Zhang, Zhong
A new type of magnetic fluid was prepared by dispersing monodispersed iron-silica (Fe-SiO 2) composite particles in polyethylene glycol (PEG) 400. The composite particles Fe-SiO 2 were synthesized by hydrogen reduction from ?-Fe 2O 3-SiO 2 spheres. Their microstructures were observed by a high-resolution transmission electron microscope (HRTEM) and the magnetism was characterized with a superconducting quantum interference device (SQUID) magnetometer. Both steady-state and dynamic rheological properties of the magnetic fluid under different magnetic fields were studied by using a rheometer. Experimental results show that this magnetic fluid has a relatively high magnetoviscous effect at low shear rates. The yield stress of this material shows an increasing trend with a magnetic flux density. Also, viscoealstic properties of such materials are different from conventional ones.
Effect of process medium on the synthesis of carbon coated lithium vanadium phosphate composite using rheological phase reaction method
Wu, Yue; Zhao, Xiaoming; Song, Zhihao; Lin, Liping; Du, Chenqiang; Tang, Zhiyuan
Li3V2(PO4)3/C composites (LVP/C) are synthesized by rheological phase reaction (RPR) method using alginic acid (HAlg) as the carbon source. Different process media are applied in the synthetic process to assess the possible effects on LVP/C composite. And the whole synthetic route is discussed in detail with qualitative and instrumental analysis, in terms of ball-milling process, rheology phase reaction process and thermogravimetric analysis of precursors. The much different morphological properties of as-prepared LVP/C composites demonstrate that process medium indeed has some effects on the synthetic process, especially on the refinement and dispersion of particles. According to these investigations, ethylene glycol (EG) is revealed more proper for preparing LVP/C using this method attributed to its moderate viscosity, surface activity and synergistic effects with HAlg. The corresponding LVP/C composite shows nanoscaled particles with smooth surfaces and uniform size distribution. Besides, LVP-EG sample exhibits excellent electrochemical performances under different voltage windows as well. Between 3.0 and 4.3�V, when charge/discharge at 20/50�C, the composite exhibits relatively high capacity and stable cycling performance for 300 cycles. Within 3.0-4.8�V, it can cycle for 200 times at a high rate of 20�C without obvious capacity fading. The outstanding performances can be attributed to the enhanced electronic/ionic conductivities of LVP/C benefitting from the influences of EG and HAlg via the RPR method.
Synthesis of LiNi0.65Co0.25Mn0.1O2 as cathode material for lithium-ion batteries by rheological phase method
International Nuclear Information System (INIS)
Research highlights: ? In this paper, for the first time, rheological phase method, a simple and effective route, was applied to synthesis high capacity cathode material LiNi0.65Co0.25Mn0.1O2. ? All of the results obtained by X-ray diffraction spectrometer, X-ray photoelectron spectrometer, charge-discharge tests and electrochemical impedance spectroscopy show that the rheological phase production have better properties than that of the report. - Abstract: Rheological phase (RP) method has been successfully applied to synthesize a promising cathode material LiNi0.65Co0.25Mn0.1O2. X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma and transmission electron microscope are used to investigate the structure, composition and morphology, respectively. XRD result shows that the as-prepared powder has a layered ?-NaFeO2 structure. XPS pattern reveals that the Ni ions have valences of 2+ and 3+, and the Co and Mn are 3+, 4+, respectively. The electrode consisting of the obtained powder presents the better electrochemical properties, which is attributed to the fewer amounts of Ni2+ ions and the smaller particles. All the results suggest that the rheological phase method is a promising technique for the preparation of LiNi0.65Co0.25Mn0.1O2 cathode material of lithium-ion batteries.f lithium-ion batteries.
Synthesis and electrochemical characterization of hybrid membrane Nafion-SiO2 for application as polymer electrolyte in PEM fuel cell
International Nuclear Information System (INIS)
In this work, the effect of sol-gel synthesis parameters on the preparation and polarization response of Nafion-SiO2 hybrids as electrolytes for proton exchange membrane fuel cells (PEMFC) operating at high temperatures (130 degree C) was evaluated. The inorganic phase was incorporated in a Nafion matrix with the following purposes: to improve the Nafion water uptake at high temperatures (> 100 degree C); to increase the mechanical strength of Nafion and; to accelerate the electrode reactions. The hybrids were prepared by an in-situ incorporation of silica into commercial Nafion membranes using an acid-catalyzed sol-gel route. The effects of synthesis parameters, such as catalyst concentration, sol-gel solvent, temperature and time of both hydrolysis and condensation reactions, and silicon precursor concentration (Tetraethyl orthosilicate - TEOS), were evaluated as a function on the incorporation degree and polarization response. Nafion-SiO2 hybrids were characterized by gravimetry, thermogravimetric analysis (TGA), scanning electron microscopy and X-ray dispersive energy (SEM-EDS), electrochemical impedance spectroscopy (EIS), and X-ray small angle scattering (SAXS). The hybrids were tested as electrolyte in single H2/O2 fuel cells in the temperature range of 80 - 130 degree C and at 130 degree C and reduced relative humidity (75% and 50%). Summarily, the hybrid performance showed to be strongly dependent on the synthesis parameters, mainly, the type of alcohol and the TEOS concentration. (author)
Synthesis and characterization of polymer electrolyte membranes with controlled ion transport properties
Xu, Kui
Ion-containing block copolymers hold promise as next-generation polymer electrolyte membrane (PEM) materials due to their capability to self-assemble into ordered nanostructures facilitating proton transport over a wide range of conditions. Ion-containing block copolymers, sulfonated poly(styrene- b-vinylidene fluoride-b-styrene), with varied degrees of sulfonation were synthesized. The synthetic strategy involved a new approach to chain-end functionalized poly(vinylidene fluoride) as a macro-initiator followed by atom transfer polymerization of styrene and sulfonation. Characterization of the polymers were extensively carried out by 1H and 19F nuclear magnetic resonance and Fouriertransform infrared spectroscopy, differential scanning calorimetry, and thermogravimetry analysis. Tapping mode atomic force microscopy and transmission electron microscopy were applied to study the phase separation and self-assembled morphology. Strong dependence of ion exchange capacity, water absorption, morphology and proton conductivity on the degree of sulfonation has been found. It has been observed that the conductivities of the block copolymers are considerably higher than the random copolymers of polystyrene and sulfonated polystyrene possessing similar ion exchange capacities. Copolymers of vinylidene fluoride and perfluoro(4-methyl-3,6-dioxane-7-ene) sulfonyl fluoride containing amino end-groups were synthesized for the first time. The prepared aminoterminated polymers underwent cross-linking reactions with 1,3,5-benzene triisocyanate to form proton conductive networks. The chain-end crosslinked fluoropolymer membranes exhibited excellent thermal, hydrolytic and oxidative stabilities. The ion exchange capacity, water uptake, the state of absorbed water, and transport properties of the membranes were found to be highly dependent upon the chemical composition of the copolymers. The cross-linked membranes showed extremely low methanol permeability, while maintaining high proton conductivity at the same order of magnitude as Nafion. This unique transport feature gave rise to exceedingly higher electrochemical selectivity in relation to Nafion. The selectivity characteristics have been rationalized based on the formation of restrained ionic domains and the state of the absorbed water within the membranes. A series of new Nafion-based composite membranes were prepared via an in situ sol-gel reaction of 3-(trihydroxylsilyl) propane-1-sulfonic acid and solution casting method. The morphological structure, ion-exchange capacity, water uptake, proton conductivity, and methanol permeability of the resulting composite membranes were extensively investigated as functions of the content of sulfopropylated polysilsesquioxane filler, temperature, and relative humidity. Unlike the conventional Nafion/silica composites, the prepared membranes exhibit an increased water uptake and associated enhancement in proton conductivity compared to unmodified Nafion. In particular, considerably high proton conductivities at 80 and 120 �C under 30% relative humidity were demonstrated in the composite membranes, which are over 2 times greater than that of Nafion. In addition to a remarkable improvement in proton conductivity, the composite membranes displayed lower methanol permeability and superior electrochemical selectivity in comparison to the pure Nafion membrane. A versatile and facile synthetic approach was developed for the preparation of a family of new ionomers with rigid aromatic backbones and pendant perfluorinated sulfonic acid groups. Variation in the chemical composition and structure of the new aromatic ionomers were performed to optimize PEM properties and fuel cell performance. The ionomers prepared from condensation polymerization of Sodium 1,1,2,2-tetrafluoro-2-(2',3',5',6'-tetrafluoro-phenoxy)- ethane sulfonate and bisphenol monomers, e.g. hydroquinone, 4,4'-biphenol, or their mixture with appropriate ratio, exhibited comparable or greater proton conductivity in relation to Nafion. New aromatic ionomers also showed other outstanding PEM prop
Synthesis and characterization of zirconia electrolytes for potential use in energy conversion
International Nuclear Information System (INIS)
The present work is part of a program to develop ionically conducting materials for potential use in energy storage and conversion systems. With applications in high energy-density batteries, magneto-hydrodynamic (MHD) generators, fuel cells and sensors, they ae playing an increasinly important role in developing more efficient energy storage and conversion devices. Using a wet-chemical procedure, a series of compostions having between 0 and 22.2 mol percent CaO in zirconia, was prepared and subsequently formed into sintered samples having a relative density from 95 to 98 percent. Sintered samples were prepared of each composition with a geometry appropriate for determining the thermal, electrical or microstructural characteristics. This report covers only the microstructural aspects of powder synthesis and the development of sintered materials. Using the reactive, homogeneous, chemically prepared powders, it has been shown that cubic and monoclinic zirconia can coexist in compositions containing up to 10 mol percent CaO. From 10 to 20 mol percent CaO, only the cubic phase is formed, whereas at higher CaO concentrations the cubic phase coexits with CaZro3. The change from a two-phase to single-phase system as the CaO concentration is increased above 10 mol percent, increases the grain size nearly an order of magnitude. It has been found that 5 and 7.6 mol percent CaO materials develop considerable stress during the cooling stage of the firing cycle. As a result, they undergo a progressive and irreversible expansion with each thermal shock cycle: the magnitude of the expansion is proportional to the severity of the thermal shock. The microstructural texture of these partially stablilized materials was also shown to be dependent on the thermal history and hence a strong dependence of the electrical and thermal properties can be anticipated. (auth)
Synthesis, rheological behavior and swelling properties of copolymer hydrogels based on poly(N-isopropylacrylamide with hydrophilic monomers
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D. Aliouche
Full Text Available In this study, hydrogels of poly(N-isopropylacrylamide-co-acrylamide and poly(N-isopropylacrylamide-co-acrylic acid having a thermoresponsive character were prepared by aqueous free-radical co-polymerization using the ammonium persulfate/N,N,N',N'-tetramethylethylenediamine (APS/TEMED redox-pair initiator system in the presence of N,N'-methylenebisacrylamide (MBAAm crosslinker. (NIPAAm-co-AAm and (NIPAAm-co-AAc hydrogels with different thermoresponsive properties were obtained by fixing the initial NIPAAm/AAm mole ratio and and (NIPAAm-co-AAc mole ratio to 80/20 and changing the crosslinker concentration. The copolymers were characterized with infrared spectroscopy (IR and differential scanning calorimetry (DSC techniques. The swelling response of the copolymers networks as a function of time, temperature and swelling environment has been observed to be dependent on both structural aspects of the polymers and swelling environment. The swelling has been observed to be decrease with increase in MBAAm in the copolypolymers networks. Rheological behavior was studies in oscillatory module. All copolymers have a viscoelastic behaviour. We note that the elastic modulus G' increases with increasing hydrophilic monomers.DOI: http://dx.doi.org/10.4314/bcse.v27i3.14
Synthesis of spinel Li4Ti5O12 anode material by a modified rheological phase reaction
International Nuclear Information System (INIS)
Using lithium acetate dihydrate and tetra-n-butyl titanate as the raw materials, spinel Li4Ti5O12 was successfully synthesized by a modified rheological phase method. Thermogravimetric analysis and differential scanning calorimetry (TG-DSC) of the thermal decomposition process of the precursor and X-ray diffraction (XRD) data indicate the crystallization of lithium titanates has occurred at 580 deg. C, and main phase Li4Ti5O12 has obtained at 600 deg. C. Laser granulometer and scanning electron microscope (SEM) have been employed to estimate the particle size distribution, morphology and microstructure of the products. It reveals the prepared Li4Ti5O12 powder had a small particle size (about 140 nm) and narrow size distribution (d0.1 = 0.07, d0.5 = 0.139, d0.9 = 2.813 ?m). Galvanostatic charge and discharge tests were carried out to characterize the electrochemical performances of Li4Ti5O12. The result indicates that the Li4Ti5O12 electrode material obtained from the precursor that had been experienced heat treatment at 110 deg. C exhibited discharge capacities of 161.6, 156.5 and 112.3 mAh g-1 after 50 cycles at current rates 1, 2.5 and 10 C, respectively, demonstrating excellent high rate performance, due to the pure and well crystallized Li4Tid well crystallized Li4Ti5O12 with ultrafine particles and narrow size distribution.
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This patent related to an electrolytic dissolver wherein dissolution occurs by solution contact including a vessel of electrically insulative material, a fixed first electrode, a movable second electrode, means for insulating the electrodes from the material to be dissolved while permitting a free flow of electrolyte therebetween, means for passing a direct current between the electrodes and means for circulating electrolyte through the dissolver
Properties of Sulfolane Based Aprotic Electrolytes
Scientific Electronic Library Online (English)
Josef, Maca; Martin, Frk; Zdenka, Rozsivalova; Marie, Sedlarikova.
Full Text Available The article deals with description of rheological and electrical properties of solvents for electrolytes of lithium-ion batteries. Solvents mixture of dimethyl sulfone and sulfolane at different volume ratios and with a lithium salt (LiClO4) appears as a potentially suitable electrolyte. In this wor [...] k, we investigate the influence of different solvents and their mixtures in order to find a solvent which increases the fire safety of such battery. The aim of this experiment is to investigate the rheological properties, particularly density and dynamic viscosity of solvents with lithium salt in temperature dependence and to find the optimal composition of the electrolyte from the perspective of achieving the lowest dynamic viscosity and better electrical conductivity, because both quantities are closely related with Walden's rule. The vibration method is used to determine the values of dynamic viscosity.
Synthesis and surface modified hard magnetic properties in Co0.5Pt0.5 nanocrystallites from a rheological liquid precursor
International Nuclear Information System (INIS)
Small crystallites of a metastable phase Co0.5Pt0.5 are precipitated by heating a rheological liquid precursor of cobalt�hydrazine complex and platinum chloride H2PtCl6�xH2O in polymer molecules of poly(vinylpyrrolidone) (PVP) in ethylene glycol. The hydrazine co-reduces nascent atoms from the Co2+ and Pt4+ that recombine and grow as Co0.5Pt0.5. The PVP molecules cap a growing Co0.5Pt0.5 as it achieves a critical size so that it stops growing further in given conditions. X-ray diffraction pattern of a recovered powder reveals a crystalline Co0.5Pt0.5 phase (average crystallite size D?8 nm) of a well-known Fm3m-fcc crystal structure with the lattice parameter a=0.3916 nm (density ?=14.09 g/cm3). A more ordered L10 phase (?=15.91 g/cm3) transforms (D?25 nm) upon annealing the powder at temperature lesser than 700 �C (in vacuum). At room temperature, the virgin crystallites bear only a small saturation magnetization Ms=5.54 emu/g (D=8 nm) of a soft magnet and it hardly grows on bigger sizes (D?31 nm) in a canted ferromagnetic structure. A rectangular hysteresis loop is markedly expanded on an optimally annealed L10 phase at 800 �C for 60 min, showing a surface modified coercivity Hc=7.781 kOe with remnant ratio Mr/Ms=0.5564, and Ms=0.5564, and Ms=39.75 emu/g. Crystallites self-assembled in an acicular shape tailor large Hc from ideal single domains and high magnetocrystalline anisotropy of a hard magnet L10 phase. - Highlights: ? A modified polyol process is reported for the synthesis of Co�Pt nanoparticles. ? Different particle sizes were obtained by varying the order of addition. ? Effect of particle size on fcc to fct phase transformation is discussed. ? Effect of heat treatments on evolution of magnetic properties is reported. ? Fully transformed Co�Pt nanoparticles resulted in a coercivity of 11.310 kOe.
Synthesis and characterization of a new hyperbranched organic-inorganic solid polymer electrolyte with cyanuric chloride as a core element
Energy Technology Data Exchange (ETDEWEB)
Pan, Yu-Chi; Saikia, Diganta [Department of Chemistry, National Central University, Chung-Li 32054, Taiwan (China); Fang, Jason; Tsai, Li-Duan [Department of Fuel Cell Materials and Advanced Capacitors, Division of Energy Storage Materials and Technology, Material and Chemical Laboratories, Industrial Technology Research Institute, Hsin-Chu 300, Taiwan (China); Fey, George T.K. [Department of Chemical and Materials Engineering, National Central University, Chung-Li 32054, Taiwan (China); Kao, Hsien-Ming, E-mail: firstname.lastname@example.com [Department of Chemistry, National Central University, Chung-Li 32054, Taiwan (China)
Highlights: > The electrolyte exhibits an ionic conductivity value of 4.4 x 10{sup -5} S cm{sup -1} at 30 deg. C. > Solid-state NMR confirms the hybrid structure of hybrid electrolytes. > Li line width reveals that the mobility of Li ion is coupled with the polymer motion. > PGSE NMR indicates that polymer segmental mobility affects Li diffusion. - Abstract: A new hyperbranched organic-inorganic hybrid electrolyte based on the use of 2,4,6-trichloro-1,3,5-triazine (cyanuric chloride, CC) as the coupling core to couple with oligo(oxyalkylene)-amines, followed by condensation with (3-glycidoxypropyl)-trimethoxysilane (GLYMO) and complexed with LiClO{sub 4}, has been prepared and characterized. The Vogel-Tamman-Fulcher (VTF) like conductivity behavior is observed in the present organic-inorganic hybrid electrolytes with a maximum ionic conductivity value of 4.4 x 10{sup -5} S cm{sup -1} at 30 deg. C. Multinuclear NMR techniques are used to provide a microscopic view for the specific interaction between the polymer chains and Li{sup +} cations and their dynamic behaviors. The results of 2D {sup 1}H-{sup 13}C wide-line separation (WISE) and {sup 7}Li static line NMR width measurements divulge that the mobility of the {sup 7}Li cations is strongly related to a dynamic environment created by the polymer motion in the amorphous phase. The combined results of conductivity and {sup 7}Li pulse-gradient spin-echo (PGSE) NMR self-diffusion coefficient measurements reveal that the conductivity enhancement at low salt concentrations is mainly caused by the high mobility of the lithium cations.
Synthesis and characterization of a new hyperbranched organic-inorganic solid polymer electrolyte with cyanuric chloride as a core element
International Nuclear Information System (INIS)
Highlights: ? The electrolyte exhibits an ionic conductivity value of 4.4 x 10-5 S cm-1 at 30 deg. C. ? Solid-state NMR confirms the hybrid structure of hybrid electrolytes. ? Li line width reveals that the mobility of Li ion is coupled with the polymer motion. ? PGSE NMR indicates that polymer segmental mobility affects Li diffusion. - Abstract: A new hyperbranched organic-inorganic hybrid electrolyte based on the use of 2,4,6-trichloro-1,3,5-triazine (cyanuric chloride, CC) as the coupling core to couple with oligo(oxyalkylene)-amines, followed by condensation with (3-glycidoxypropyl)-trimethoxysilane (GLYMO) and complexed with LiClO4, has been prepared and characterized. The Vogel-Tamman-Fulcher (VTF) like conductivity behavior is observed in the present organic-inorganic hybrid electrolytes with a maximum ionic conductivity value of 4.4 x 10-5 S cm-1 at 30 deg. C. Multinuclear NMR techniques are used to provide a microscopic view for the specific interaction between the polymer chains and Li+ cations and their dynamic behaviors. The results of 2D 1H-13C wide-line separation (WISE) and 7Li static line NMR width measurements divulge that the mobility of the 7Li cations is strongly related to a dynamic environment created by the polymer motion in the amorphous phase. The combined results of conductivity and 7Li pulse-gradient spin-echo (PGSp>Li pulse-gradient spin-echo (PGSE) NMR self-diffusion coefficient measurements reveal that the conductivity enhancement at low salt concentrations is mainly caused by the high mobility of the lithium cations.
Synthesis and Compatibility of Ionic Liquid Containing Rod-Coil Polyimide Gel Electrolytes with Lithium Metal Electrodes
Tigelaar, Dean M.; Palker, Allyson E.; Meador, Mary Ann B.; Bennett, William R.
A highly cross-linked polyimide-polyethylene oxide copolymer has been synthesized that is capable of holding large volumes of liquid component, simultaneously maintaining good dimensional stability. An amine end capped oligomer was made that was imidized in solution, followed by reaction with a triisocyanate in the presence of desired additives at ambient temperature. Polymer films are able to hold over 4 times their weight in room temperature ionic liquid RTIL or carbonate solvent. Electrolytes were studied that contained varying amounts of RTIL, lithium trifluoromethanesulfonimide LiTFSi, and alumina nanoparticles. Electrochemical stability of these electrolytes with lithium metal electrodes was studied by galvanic cycling and impedance spectroscopy. Improved cycling stability and decreased interfacial resistance were observed when increasing amounts of RTIL and LiTFSi were added. The addition of small amounts of alumina further decreased interfacial resistance by nearly an order of magnitude. During the course of the study, cycling stability increased from less than 3 to greater than 1000 h at 60 C and 0.25 mA/cm2 current density.
Synthesis and surface modified hard magnetic properties in Co{sub 0.5}Pt{sub 0.5} nanocrystallites from a rheological liquid precursor
Energy Technology Data Exchange (ETDEWEB)
Kalyan Kamal, S.S., E-mail: firstname.lastname@example.com [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500 058 (India); Sahoo, P.K.; Durai, L.; Ghosal, P.; Manivel Raja, M. [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500 058 (India); Ram, S. [Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302 (India)
Small crystallites of a metastable phase Co{sub 0.5}Pt{sub 0.5} are precipitated by heating a rheological liquid precursor of cobalt-hydrazine complex and platinum chloride H{sub 2}PtCl{sub 6}{center_dot}xH{sub 2}O in polymer molecules of poly(vinylpyrrolidone) (PVP) in ethylene glycol. The hydrazine co-reduces nascent atoms from the Co{sup 2+} and Pt{sup 4+} that recombine and grow as Co{sub 0.5}Pt{sub 0.5}. The PVP molecules cap a growing Co{sub 0.5}Pt{sub 0.5} as it achieves a critical size so that it stops growing further in given conditions. X-ray diffraction pattern of a recovered powder reveals a crystalline Co{sub 0.5}Pt{sub 0.5} phase (average crystallite size D{approx}8 nm) of a well-known Fm3m-fcc crystal structure with the lattice parameter a=0.3916 nm (density {rho}=14.09 g/cm{sup 3}). A more ordered L1{sub 0} phase ({rho}=15.91 g/cm{sup 3}) transforms (D{>=}25 nm) upon annealing the powder at temperature lesser than 700 Degree-Sign C (in vacuum). At room temperature, the virgin crystallites bear only a small saturation magnetization M{sub s}=5.54 emu/g (D=8 nm) of a soft magnet and it hardly grows on bigger sizes (D{<=}31 nm) in a canted ferromagnetic structure. A rectangular hysteresis loop is markedly expanded on an optimally annealed L1{sub 0} phase at 800 Degree-Sign C for 60 min, showing a surface modified coercivity H{sub c}=7.781 kOe with remnant ratio M{sub r}/M{sub s}=0.5564, and M{sub s}=39.75 emu/g. Crystallites self-assembled in an acicular shape tailor large H{sub c} from ideal single domains and high magnetocrystalline anisotropy of a hard magnet L1{sub 0} phase. - Highlights: Black-Right-Pointing-Pointer A modified polyol process is reported for the synthesis of Co-Pt nanoparticles. Black-Right-Pointing-Pointer Different particle sizes were obtained by varying the order of addition. Black-Right-Pointing-Pointer Effect of particle size on fcc to fct phase transformation is discussed. Black-Right-Pointing-Pointer Effect of heat treatments on evolution of magnetic properties is reported. Black-Right-Pointing-Pointer Fully transformed Co-Pt nanoparticles resulted in a coercivity of 11.310 kOe.
Solid Electrolyte Materials for use in Lithium-water Primary Batteries And the Synthesis and Characterization of Lanthanide Orthoferrite Magnetic Nanomaterials
Cook, Clifford Corlin
This thesis was developed in two parts with the overall goals of this work being (1) synthesize and develop solid electrolyte materials for use in a lithium-water battery and (2) synthesize and characterize ternary magnetic nanomaterials. Lithium metal in combination with water is a highly attractive power source due to its high specific energy. Because of the vigorous nature of the reaction between lithium and water, many obstacles must be overcome in order to harness the energy that this system is capable of producing. Parasitic reactions must be controlled so as not to passivate the lithium or consume it totally. In addition, production of hydrogen gas that accompanies both the electrochemical and parasitic reactions can present a serious challenge. As a result it is difficult to maintain high voltage and control the current density in these systems. In order to overcome these obstacles we have developed composite membranes of various lithium-ion conducting solid electrolytes and polymers. Lithium-ion conducting solid electrolytes are known to achieve ionic conductance as high as 10-3 S/cm2. Utilizing these materials in conjunction with polymers, we have created hydrophobic membranes that allow us to limit the parasitic reactions and maintain low cell impedance. Lanthanide orthoferrite materials are technologically important classes of magnetic materials. They have found application in magneto-optical devices as well as in magnetic recording devices. We have explored the syntheses and magnetic properties of nanocrystalline materials. The synthesis of the nanomaterials was done by co-reduction of lanthanide, Ln3+, and iron, Fe 3+, cations with alkalide solution producing the Ln-Fe alloy of the desired stoichiometry. Removal of the byproducts and oxidization of the alloy was accomplished by washing the product with aerated water. Presented herein, several nanoscale lanthanide orthoferrite materials (LnFeO3, Ln = Gd, Tb, Er, Tm, Sm, Dy, Ho, and La) have been prepared. The products have been characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and magnetic properties characterized by use of a Superconducting Quantum Interference Device (SQUID).
Synthesis and morphological change in poly(ethylene oxide)-sodium chlorate based polymer electrolyte complex with polyaniline
Kunteppa, H.; Roy, Aashis S.; Koppalkar, Anil R.; Ambika Prasad, M. V. N.
The composites of polyethylene oxide:polyaniline:sodium chlorate is prepared by stirring with anhydrous acetonitrile for 5-6 h to form homogeneous solutions/gels at different weight percentages. The composites are characterized by FTIR and SEM. The predominant peaks that appeared in FTIR spectra confirm the formation of PEO:PANI:NaClO 4 composites. It is found from the SEM studies that there is a significant change in the morphology of various weight percentages of NaClO 4 in PEO-PANI matrix, i.e. from ellipsoidal to square. DC conductivity behavior is seen due to hopping of polarons from one localized state to another that can be confirmed by Mott theory. It is observed from the DC conductivity and SEM studies that these composites can be promising candidates for solid state electrolytes.
Synthesis of BICUVOX solid electrolyte thin film on tantalum substrate by spray pyrolysis technique for biomedical sensors
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Solid electrolytes find their application in many fields of technological interest such as oxygen sensor, fuel cell, and oxygen pump. Oxygen sensors form a basic component of biomedical instrumentation. Out of all known oxygen ion conducting solid electrolytes, metal ion substituted bismuth vanadate exhibits maximum oxygen ion conductivity at comparatively lower temperature. Thin film of Bi2Cu0.1 V0.9O5.35 was synthesized by an innovative and cost effective spray pyrolysis technique at 493 K on tantalum substrate. Tantalum is a metal with high oxygen affinity. The precursor solution was sprayed on pre heated tantalum substrate, at an optimized spray rate to obtain a uniform film. Film was then annealed at 973 K for two hours to obtain required ion conducting phase. The phase was confirmed with XRD studies. The bulk ionic conductivity of the film was measured by the method of electrochemical impedance spectrometry. The impedance measurements were done in the frequency range 1Hz to 10MHz with respect to temperature. The measurements were carried out in air ambience i.e. at 0.21 oxygen partial pressure. The ionic conductivity was found to be increasing with increase in temperature. It is about 2.53x10-5 (ohm cm)-l at 864K. The lessening of conductivity is attributed in this case to phase separation in the film. Oxygen ion conducting film on metallic substrate is expected to serve as good oxygen sensor in bpected to serve as good oxygen sensor in biomedical instrumentation. (author)
Propriedades reol�gicas e microestruturais de eletr�lito de ZrO2/Y2O3 / Microstructural and rheological properties of ZrO2/Y2O3 electrolyte
Scientific Electronic Library Online (English)
H.A., Taroco; R. M. F., Basaglia; R. Z., Domingues; M., Brant; T., Matencio.
Full Text Available Para reduzir a temperatura de opera��o das pilhas a combust�vel de �xido s�lido (PaCOS), estruturas com filmes finos de eletr�lito depositados, por aerografia, sobre suportes de anodo porosos foram desenvolvidas. As barbotinas, empregadas para fabrica��o dos filmes, foram preparadas a partir de susp [...] ens�es com p�s de zirc�nia estabilizada com �tria (ZEI), solventes, dispersantes, ligantes e plastificantes apropriados. Neste trabalho, foi feito o estudo da influ�ncia dos ligantes sobre a estabilidade das suspens�es e as propriedades microestruturais dos filmes de ZEI. Tr�s barbotinas foram elaboradas com composi��es diferentes de ligantes (0,5; 1,0 e 2,0 % p/p). Todas apresentaram comportamento de fluidos pseudopl�sticos e tixotr�picos, de acordo com medidas de viscosidade e taxa de cisalhamento. Os filmes foram sinterizados a 1500 �C/6h. As micrografias eletr�nicas de varredura (MEV) foram tratadas atrav�s do programa Quantikov para determinar a porosidade do filme e o tamanho m�dio de gr�o da ZEI. Os filmes apresentaram porosidade adequada para serem empregados como eletr�lito das PaCOS (entre 0,2 e 0,4 % ) e tamanho m�dio de gr�o entre 2,0 e 6,0 �m. A t�cnica de aerografia � adequada para fabricar eletr�lito de ZEI para PaCOS. Abstract in english To reduce the operating temperature of solid oxide fuel cells, structures with thin films electrolytes, deposited by spray coating on porous anode were developed. The slurries used for the fabrication of the films were prepared using appropriates suspensions with ytria-stabilized zirconia (YSZ) powe [...] rs, solvents, dispersants, binders and plasticizers appropriates. In this work the study of the influence of the binders in the stability of the suspensions and the microstructures properties of the YSZ films were done. Three slurries were made with different composition of binders (0.5; 1.0 and 2.0 % in weight). All of them showed pseudo-plastics and thixotropics flow behavior, according to viscosities measurements and shear rate. The films were sintered to 1500 �C /6 hours. The images of scanning electron micrographs (SEM) were treated by Quantikov program to determine the porosity of the film and average grain size of YSZ. The films showed adequate porosity for being used as SOFC electrolyte (between 0.2 and 0.4%) and average grain size between 2.0 and 6.0 � m. The spray coating is a suitable technique to fabricate the YSZ electrolytes for SOFC.
The Synthesis and Characterization of Ionic Liquids for Alkali-Metal Batteries and a Novel Electrolyte for Non-Humidified Fuel Cells
Tucker, Telpriore G.
This thesis focused on physicochemical and electrochemical projects directed towards two electrolyte types: 1) class of ionic liquids serving as electrolytes in the catholyte for alkali-metal ion conduction in batteries and 2) gel membrane for proton conduction in fuel cells; where overall aims were encouraged by the U.S. Department of Energy. Large-scale, sodium-ion batteries are seen as global solutions to providing undisrupted electricity from sustainable, but power-fluctuating, energy production in the near future. Foreseen ideal advantages are lower cost without sacrifice of desired high-energy densities relative to present lithium-ion and lead-acid battery systems. Na/NiCl2 (ZEBRA) and Na/S battery chemistries, suffer from high operation temperature (>300�C) and safety concerns following major fires consequent of fuel mixing after cell-separator rupturing. Initial interest was utilizing low-melting organic ionic liquid, [EMI+][AlCl 4-], with well-known molten salt, NaAlCl4, to create a low-to-moderate operating temperature version of ZEBRA batteries; which have been subject of prior sodium battery research spanning decades. Isothermal conductivities of these electrolytes revealed a fundamental kinetic problem arisen from "alkali cation-trapping effect" yet relived by heat-ramping >140�C. Battery testing based on [EMI+][FeCl4 -] with NaAlCl4 functioned exceptional (range 150-180�C) at an impressive energy efficiency >96%. Newly prepared inorganic ionic liquid, [PBr4+][Al2Br7-]:NaAl2Br 7, melted at 94�C. NaAl2Br7 exhibited super-ionic conductivity 10-1.75 Scm-1 at 62�C ensued by solid-state rotator phase transition. Also improved thermal stability when tested to 265�C and less expensive chemical synthesis. [PBr4 +][Al2Br7-] demonstrated remarkable, ionic decoupling in the liquid-state due to incomplete bromide-ion transfer depicted in NMR measurements. Fuel cells are electrochemical devices generating electrical energy reacting hydrogen/oxygen gases producing water vapor. Principle advantage is high-energy efficiency of up to 70% in contrast to an internal combustion engine cells are prone to carbon monoxide catalytic poisoning and polymer membrane degradation unless heavily hydrated under cell-pressurization. This novel "SiPOH" solid-electrolytic gel (originally liquid-state) operated in the fuel cell at 121�C yielding current and power densities high as 731mAcm-2 and 345mWcm-2, respectively. Enhanced proton conduction significantly increased H2 fuel efficiency to 89.7% utilizing only 3.1mlmin-1 under dry, unpressurized testing conditions. All these energy devices aforementioned evidently have future promise; therefore in early developmental stages.
Influence of arc duration time on the synthesis of carbon nanohorns by a gas-injected arc-in-water system: application to polymer electrolyte fuel cell electrodes
International Nuclear Information System (INIS)
Single-walled carbon nanohorns (SWCNH) can be synthesized by a gas-injected arc-in-water (GI-AIW) method at low cost. This study revealed the influence of arc discharge duration time on the yield of SWCNH in the synthesis using this method. As a result, the yield of SWCNH increased with the arc discharge duration time, while an increase in arc plasma temperature was observed. This result can be explained by considering that the increased temperature of the reaction zone can lead to an increase in carbon radical density, which can positively affect the production yield. Here, two arc discharge modes, continuous and discrete, were generated so that modes having different temperatures with the same discharge current could be compared. From this investigation, it was suggested that an excessive ion density may cause a decrease in SWCNH production. The as-grown SWCNH possessed a high specific surface area when the arc discharge current was optimized with continuous arc mode using the GI-AIW method. Such a product can support Pt catalyst with high dispersivity, leading to high performance in polymer electrolyte fuel cells as catalyst layers.
Electrochemical ammonia synthesis from steam and nitrogen using proton conducting yttrium doped barium zirconate electrolyte with silver, platinum, and lanthanum strontium cobalt ferrite electrocatalyst
Yun, Dae Sik; Joo, Jong Hoon; Yu, Ji Haeng; Yoon, Hyung Chul; Kim, Jong-Nam; Yoo, Chung-Yul
Electrochemical ammonia synthesis from steam and nitrogen has been systematically investigated using a proton-conducting electrolyte supported cell based on 20 mol% yttrium doped barium zirconate (BaZr0.8Y0.2O3-?) in a temperature range of 475-600 �C at atmospheric pressure. Silver (Ag), platinum (Pt), and lanthanum strontium cobalt ferrite (La0.6Sr0.4Co0.2Fe0.8O3-?) are used for both anode and cathode electrocatalysts. Maximum ammonia formation rates of 4.9 � 10-11 mol cm-2 s-1 and 8.5 � 10-11 mol cm-2 s-1 are observed for Ag and La0.6Sr0.4Co0.2Fe0.8O3-? electrocatalysts, respectively, when a voltage of 0.8 V is applied. However, Pt electrocatalyst shows a negligible ammonia formation rate lower than 1 � 10-12 mol cm-2 s-1. This is ascribed to the high activity of Pt for the hydrogen evolution reaction rather than the ammonia formation reaction. The conversion efficiency of all electrocatalysts is below 1%, primarily due to the limited nitrogen disassociation activity of the electrocatalysts.
Directory of Open Access Journals (Sweden)
G. Ranalli
Full Text Available The distribution of the rheological properties of the lithosphere in space, and their variations in time, have a profound effect on the resulting tectonic deformation. A classical way of estimating these properties makes use of rheological profiles (strength envelopes. Although rheological profiles are based on assumptions and approximations which limit their resolving power, they are an efficient first-order tool for the study of lithosphere rheology, and their application clarifies the dynamics of tectonic processes. Two examples of the interaction of rheology and tectonics are discussed, namely, the post-orogenic relaxation of Moho topography (which is an additional factor to be considered in tectonic inversion, and the strength control on the level of necking in extension (which may lead to apparent local isostasy at passive continental margins and in sedimentary basins.
Synthesis of amorphous silica and sulfonic acid functionalized silica used as reinforced phase for polymer electrolyte membrane
International Nuclear Information System (INIS)
In this work silica (SiO2) and sulfonic acid-functionalized silica (sul-SiO2) were synthesized by sol�gel method from tetraethoxysilane (TEOS) and 3-mercatopropyltrimethoxysilane (MPTMS) with various ratios between them. The synthesized materials were characterized by x-ray diffraction (XRD) for crystalline structure, Brunauer�Emmet�Teller (BET) specific surface area analysis, transmission electronic microscopy (TEM) and dynamic light scattering (DLS) for particle size analysis, and ion exchange capacity (IEC) for determining sulfur content in Sul-SiO2 materials. The initial results showed that the average particle size of amorphous SiO2 and Sul-SiO2 at different TEOS: MPTMS ratios are in narrow distribution with average diameter about 20�30 nm. The particle size of Sul-SiO2 is almost unaffected by the content of MPTMS while IEC depends strongly on it. Composite membranes of 60 ?m thickness were successfully prepared from blending of poly(vinylidene fluoride) (PVDF) and synthesized amorphous SiO2. It was shown that the latter may be used as a reinforced phase for composite membrane electrolytes based on PVDF. (paper)
Synthesis of amorphous silica and sulfonic acid functionalized silica used as reinforced phase for polymer electrolyte membrane
Nhan Tran, Thanh; Pham, Thi Van Anh; Loan Phung Le, My; Phuong Thoa Nguyen, Thi; Tran, Van Man
In this work silica (SiO2) and sulfonic acid-functionalized silica (sul-SiO2) were synthesized by sol�gel method from tetraethoxysilane (TEOS) and 3-mercatopropyltrimethoxysilane (MPTMS) with various ratios between them. The synthesized materials were characterized by x-ray diffraction (XRD) for crystalline structure, Brunauer�Emmet�Teller (BET) specific surface area analysis, transmission electronic microscopy (TEM) and dynamic light scattering (DLS) for particle size analysis, and ion exchange capacity (IEC) for determining sulfur content in Sul-SiO2 materials. The initial results showed that the average particle size of amorphous SiO2 and Sul-SiO2 at different TEOS: MPTMS ratios are in narrow distribution with average diameter about 20�30 nm. The particle size of Sul-SiO2 is almost unaffected by the content of MPTMS while IEC depends strongly on it. Composite membranes of 60 ?m thickness were successfully prepared from blending of poly(vinylidene fluoride) (PVDF) and synthesized amorphous SiO2. It was shown that the latter may be used as a reinforced phase for composite membrane electrolytes based on PVDF.
Synthesis and characterization of sulfonated poly(ether sulfone)s containing mesonaphthobifluorene for polymer electrolyte membrane fuel cell.
Lim, Youngdon; Seo, Dongwan; Lee, Soonho; Hossain, Md Awlad; Lim, Jinseong; Lee, Sangyoung; Hong, Taehoon; Kim, Whangi
The novel sulfonated poly(ether sulfone)s containing mesonaphthobifluorene (MNF) moiety were synthesized and characterized their properties. The prepared polymers have highly conjugated aromatic structure due to the MNF group which is an allotrope of carbon and one atom thick planar sheets of sp2-bonded carbon atoms. Poly(ether sulfone)s bearing tetraphenylethylene on polymer backbone were synthesized by polycondensation and followed intra-cyclization from tetraphenylethylene to form MNF by Friedel-craft reaction with Lewis acid (FeCl3). The sulfonation was performed selectively on MNF units with conc. sulfuric acid. The structural properties of the sulfonated polymers were investigated by 1H-NMR spectroscopy. The membranes were studied by ion exchange capacity (IEC), water uptake, and proton conductivity. The synthesized polymer electrolyte membranes showed better thermal and dimensional stabilities owing to the inducted highly conjugated aromatic structure in the polymer backbone. The water uptake of the synthesized membranes ranged from 23-52%, compared with 32.13% for Nafion 211 at 80 degrees C. The synthesized membranes exhibited proton conductivities (80 degrees C, RH 90%) of 74.6-100.4 mS/cm, compared with 102.7 mS/cm for Nafion 211. PMID:25942900
Rheological phenomena in focus
Boger, DV
More than possibly any other scientific discipline, rheology is easily visualized and the relevant literature contains many excellent photographs of unusual and often bizarre phenomena. The present book brings together these photographs for the first time. They are supported by a full explanatory text. Rheological Phenomena in Focus will be an indispensable support manual to all those who teach rheology or have to convince colleagues of the practical relevance of the subject within an industrial setting. For those who teach fluid mechanics, the book clearly illustrates the difference be
Design and Synthesis of Cross-Linked Copolymer Membranes Based on Poly(benzoxazine and Polybenzimidazole and Their Application to an Electrolyte Membrane for a High-Temperature PEM Fuel Cell
Directory of Open Access Journals (Sweden)
Hyuk Chang
Full Text Available Elevated-temperature (100~200 �C polymer electrolyte membrane (PEM fuel cells have many features, such as their high efficiency and simple system design, that make them ideal for residential micro-combined heat and power systems and as a power source for fuel cell electric vehicles. A proton-conducting solid-electrolyte membrane having high conductivity and durability at elevated temperatures is essential, and phosphoric-acid-containing polymeric material synthesized from cross-linked polybenzoxazine has demonstrated feasible characteristics. This paper reviews the design rules, synthesis schemes, and characteristics of this unique polymeric material. Additionally, a membrane electrode assembly (MEA utilizing this polymer membrane is evaluated in terms of its power density and lifecycle by an in situ accelerated lifetime test. This paper also covers an in-depth discussion ranging from the polymer material design to the cell performance in consideration of commercialization requirements.
Polyelectrolytes thermodynamics and rheology
P M, Visakh; Pic�, Guillermo
This book discusses current development of theoretical models and experimental findings on the thermodynamics of polyelectrolytes. Particular emphasis is placed on the rheological description of polyelectrolyte solutions and hydrogels.
Rheological phase reaction synthesis and electrochemical performance of Li3V2(PO4)3/carbon cathode for lithium ion batteries
International Nuclear Information System (INIS)
Monoclinic lithium vanadium phosphate/carbon (Li3V2(PO4)3/C) cathode has been synthesized for applications in lithium ion batteries, via a rheological phase reaction (RPR) method. The sample is characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). This material exhibits high initial discharge capacity of 189 and 177 mAh g-1 at 0.1 and 0.2 C between 3.0 and 4.8 V, respectively. Moreover, it displays good fast rate performance, which discharge capacities of 140, 133, 129 and 124 mAh g-1 can be delivered after 100 cycles between 3.0 and 4.8 V vs. Li at a different rate of 0.5, 1, 2 and 5 C, respectively. The electrochemical impedance spectroscopy (EIS) is also investigated
International Nuclear Information System (INIS)
The emphasis is made on experimentally observed indications of the presence of metastable ion dipoles in solid helium. Similar quasiparticles possessing positive scattering length for injected electrons are assumed to exist in liquid phases of cryogenic liquids. The observed phenomena allowing to detect and monitor the behavior of dipole gas in superfluid helium (referred to as cryogenic electrolyte) are discussed. Most interesting among these phenomena are: special features of the dielectric behavior of ion dipole gas, details of the temperature dependence of the ion dipole gas osmotic pressure at the boundary of the liquid 3He-4He solution stratification, relaxation phenomena of collective origin in cryogenic electrolytes, and liquid helium phonon spectrum transformation due to strong interaction between phonons and heavy dipole quasiparticles.
Nazin, S.; Chikina, I.; Shikin, V.
Experimental evidence of metastable ion dipoles in solid helium is examined. Similar quasiparticles with positive scattering lengths for injected electrons are assumed to exist in the liquid phases of cryogenic liquids. Phenomena that can be used for detecting and monitoring a dipole gas in superfluid helium (referred to as cryogenic electrolyte) are discussed. The most interesting of these phenomena are: special features of the dielectric behavior of ion dipole gases, the temperature dependence of the ion dipole gas osmotic pressure at the boundary of liquid 3He-4He solution stratification, relaxation phenomena of collective origin in cryogenic electrolytes, and the transformation of the phonon spectrum of liquid helium owing to strong interactions between phonons and heavy dipole quasiparticles.
Chen, Daniel
Active networks drive a diverse range of critical processes ranging from motility to division in living cells, yet a full picture of their rheological capabilities in non-cellular contexts is still emerging, e.g., How does the rheological response of a network capable of remodeling under internally-generated stresses differ from that of a passive biopolymer network? In order to address this and other basic questions, we have engineered an active gel composed of microtubules, bidirectional kinesin motors, and molecular depletant that self-organizes into a highly dynamic network of active bundles. The network continually remodels itself under ATP-tunable cycles of extension, buckling, fracturing, and self-healing. Using confocal rheometry we have simultaneously characterized the network's linear and non-linear rheological responses to shear deformation along with its dynamic morphology. We find several surprising and unique material properties for these active gels; most notably, rheological cloaking, the ability of the active gel to drive large-scale fluid mixing over several orders of flow magnitude while maintaining an invariant, solid-like rheological profile and spontaneous flow under confinement, the ability to exert micro-Newton forces to drive persistent directed motion of the rheometer tool. Taken together, these results and others to be discussed highlight the rich stress-structure-dynamics relationships in this class of biologically-derived active gels.
Chocolate rheology Reologia de chocolate
Estela Vidal Gon�alves; Suzana Caetano da Silva Lannes
Rheology is the science that studies the deformation and flow of solids and fluids under the influence of mechanical forces. The rheological measures of a product in the stage of manufacture can be useful in quality control. The microstructure of a product can also be correlated with its rheological behavior allowing for the development of new materials. Rheometry permits attainment of rheological equations applied in process engineering, particularly unit operations that involve heat and mas...
Aerosol synthesis and electrochemical analysis of niobium mixed-metal oxides for the ethanol oxidation reaction in acid and alkaline electrolyte
Konopka, Daniel A.
Direct ethanol fuel cells are especially important among emerging electrochemical power systems with the potential to offset a great deal of the energy demand currently met through the use of fossil fuels. Ethanol can be refined from petroleum sources or attained from renewable biomass, and is more easily and safely stored and transported than hydrogen, methanol or gasoline. The full energy potential of ethanol in fuel cells can only be realized if the reaction follows a total oxidation pathway to produce CO2. This must be achieved by the development of advanced catalysts that are electrically conductive, stable in corrosive environments, contain a high surface area on which the reaction can occur, and exhibit a bi-functional effect for the ethanol oxidation reaction (EOR). The latter criterion is achievable in mixed-metal systems. Platinum is an effective metal for catalyzing surface reactions of many adsorbates and is usually implemented in the form of Pt nanoparticles supported on inexpensive carbon. This carbon is believed to be neutral in the catalysis of Pt. Instead, carbon can be replaced with carefully designed metals and metal oxides as co-catalysis or support structures that favorably alter the electronic structure of Pt slightly through a strong metal support interaction, while also acting as an oxygen source near adsorbates to facilitate the total oxidation pathway. Niobium mixed-metal-oxides were explored in this study as bi-functional catalyst supports to Pt nanoparticles. We developed a thermal aerosol synthesis process by which mesoporous powders of mixed-metal-oxides decorated with Pt nanoparticles could be obtained from liquid precursors within �5 seconds or less, followed by carefully refined chemical and thermal post-treatments. Exceptionally high surface areas of 170--180m2/g were achieved via a surfactant-templated 3D wormhole-type porosity, comparable on a per volume basis to commercial carbon blacks and high surface area silica supports. For the first time, in situ FTIR measurements in acid electrolyte showed that highly dispersed Pt nanoparticles (2--5nm) on NbRuyO z (at% 8Nb:1Ru) catalyze the formation of CO2 from ethanol in greater yield, and 0.35--0.4V lower, than Pt(111). Compared to conventional Pt/carbon, this indicates that, (1) Pt supported on NbRuyO z can be more effective at splitting the C---C bond in ethanol and, (2) the scission occurs at potentials more ideal for a higher efficiency fuel cell anode. Ex situ-microscopy revealed the polarization-induced two- and three-dimensional formation of Pt-NbOx interfacial adsorption sites responsible for the facilitation of the total oxidation pathway of ethanol. The results show that synthesis and post-treatment of niobia supports can bias the utility of Pt/niobia systems towards the ethanol oxidation reaction at the anode or the oxygen reduction reaction at the cathode. Experimental and computational-theoretical analyses indicate that the mechanism of interfacial site formation is dependent upon the local oxygen concentration, as well as the availability of multiple, energetically accessible oxidation states like those inherent to niobia. Future directions for the development of highly active, niobium-based materials tailored for efficient catalysis of the total oxidation pathway of ethanol are discussed.
Rheological phase synthesis and characterization of Li3V2(PO4)3/C composites as cathode materials for lithium ion batteries
International Nuclear Information System (INIS)
Li3V2(PO4)3/C composites as cathode materials for lithium ion batteries were successfully synthesized through the rheological phase reaction method using LiOH�H2O, V2O5, NH4H2PO4, and C6H8O7�H2O as raw materials. The as-prepared powders were characterized by means of powder X-ray diffraction (XRD), scan electron microscope (SEM), and transmission electron microscope (TEM). The electrochemical properties of Li3V2(PO4)3/C composites were examined by the galvanostatic charge/discharge, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicate that the sintering temperatures have a significant effect on the crystal structure, morphology, and electrochemical performances of Li3V2(PO4)3/C composites. XRD reveals that Li3V2(PO4)3/C composites are well crystallized single phase, where Li3V2(PO4)3/C composite synthesized at 800 �C for 8 h displays the maximum cell volume and uniformly distributed particles. It can be seen from TEM that there is a carbon layer of about 200-500 nm thick on the particle surface. The apparent DLi+ calculated from CV is in the order of magnitude of 10?7 cm2 s?1. Electrochemical tests show that Li3V2(PO4)3/C composite synthesized at 800 �C for 8 h exhibits excellent cycling performance of 129.149 mAh g?1 after 60 cycles at the current of 15 mA g?1 and a superior rate capability of 112.101 mAh g?1 after 60 cycles at the current of 90 mA g?1
Solid state electrolyte systems
Energy Technology Data Exchange (ETDEWEB)
Pederson, L.R.; Armstrong, B.L.; Armstrong, T.R. [Pacific Northwest Lab., Richland, WA (United States)] [and others
Lanthanum gallates are a new family of solid electrolytes that exhibit high ionic conductivity and are stable to high temperatures. Compositions have been developed that are as much as a factor of two more conductive than yttria-stabilized zirconia at a given temperature, through partial replacement of lanthanum by calcium, strontium, and/or barium and through partial replacement of gallium by magnesium. Oxide powders were prepared using combustion synthesis techniques developed in this laboratory; these were sintered to >95% of theoretical density and consisted of a single crystalline phase. Electrical conductivities, electron and ion transference numbers, thermal expansion, and phase behavior were evaluated as a function of temperature and oxygen partial pressure. A key advantage of the use of lanthanum gallate electrolytes in solid oxide fuel cells is that the temperature of operation may be lowered to perhaps 800 C, yet provide approximately the same power density as zirconia-based cells operating at 1000 C. Ceramic electrolytes that conduct both oxygen ions and electrons are potentially useful to passively separate pure oxygen from an air source at low cost. In such materials, an oxygen ion flux in one direction is charge-compensated by an opposing electron flux. The authors have examined a wide range of mixed ion and electron conducting perovskite ceramics in the system La{sub 1{minus}x}M{sub x}Co{sub 1{minus}y{minus}z}Fe{sub y}N{sub z}O{sub 3{minus}{delta}}, where M = Sr, Ca, and Ba, and N = Pr, Mn, Ni, Cu, Ti, and Al, as well as mixed conducting brownmillerite ceramics, and have characterized oxygen permeation behavior, defect chemistry, structural and phase stability, and performance as cathodes.
Blanc, R.
In this paper we briefly present the main relevant physical quantities in the rheology of concentrated dispersions. Main lines of three topics (shear viscosity, sedimentation velocity and aggregation processes) are then given. The importance or ordered or random structures is emphasized.
Molten o-H3PO4: A New Electrolyte for the Anodic Synthesis of Self-Organized Oxide Structures - WO3 Nanochannel Layers and Others.
Altomare, Marco; Pfoch, Ole; Tighineanu, Alexei; Kirchgeorg, Robin; Lee, Kiyoung; Selli, Elena; Schmuki, Patrik
We introduce the use of pure molten ortho-phosphoric acid (o-H3PO4) as an electrolyte for self-organizing electrochemistry. This electrolyte allows for the formation of self-organized oxide architectures (one-dimensional nanotubes, nanochannels, nanopores) on metals such as tungsten that up to now were regarded as very difficult to grow self-ordered anodic oxide structures. In this work, we show particularly the fabrication of thick, vertically aligned tungsten oxide nanochannel layers, with pore diameter of ca. 10 nm and illustrate their potential use in some typical applications. PMID:25884483
Dollet, Benjamin; Raufaste, Christophe
Aqueous foams are suspensions of bubbles inside aqueous phases. Their multiphasic composition leads to a complex rheological behavior that is useful in numerous applications, from oil recovery to food/cosmetic processing. Their structure is very similar to the one of emulsions, so that both materials share common mechanical properties. In particular, the presence of surfactants at the gas-liquid interfaces leads to peculiar interfacial and dissipative properties. Foam rheology has been an active research topics and is already reported in several reviews, most of them covering rheometry measurements at the scale of the foam, coupled with interpretations at the local scale of bubbles or interfaces. In this review, we start following this approach, then we try to cover the multiscale features of aqueous foam flows, emphasizing regimes where intermediate length scales need to be taken into account or regimes fast enough regarding internal time scales so that the flow goes beyond the quasi-static limit. xml:lang="fr"
Synthesis, processing and characterization of the solid oxide half-cells cathode/electrolyte of strontium-doped lanthanum manganite/Yttria-stabilized zirconia
International Nuclear Information System (INIS)
The ceramic films of strontium-doped lanthanum manganite (LSM) and strontium doped lanthanum manganite/Yttria-stabilized zirconia (LSM/YSZ) are used as cathodes of the high temperature solid oxide fuel cells (HTSOFC). These porous ceramic films had been deposited on the YSZ dense ceramic substrate, used as electrolyte, structural component of the module, thus conferring a configuration of half-cell called auto-support. The study of the half-cell it is basic, therefore in the interface cathode/electrolyte occurs the oxygen reduction reaction, consequently influencing in the performance of the HTSOFC. In this direction, the present work contributes for the processing of thin films, using the wet powder spraying technique, adopted for the conformation of the ceramic films for allowing the attainment of porous layers with thicknesses varied in the order of micrometers. The LSM powders were synthesized by the citrate technique and the LSM/YSZ powders synthesized by the solid mixture technique. In the stage of formation were prepared organic suspensions of LSM and LSM/YSZ fed by gravity in a manual aerograph. For the formation of the YSZ substrate was used a hydraulic uniaxial press. The attainment of solid oxide half-cells cathode/electrolyte was possible of crystalline structures hexagonal for phase LSM and cubic for phase YSZ. The half-cells micrographs show that the YSZ substrate is dense, enough to be used as solid electrolyte, and the LSM and LSM/YSZ films are presented porous with approximately 30 ?m of thickness and good adherence between the cathodes and the electrolyte. The presence of composite cathode between the LSM cathode and YSZ substrate, presented an increase in the electrochemical performance in the oxygen reduction reaction. (author)
Rheological behavior study of a clay-polymer mixture: effects of the polymer addition
International Nuclear Information System (INIS)
The aim of the present work is to establish a bibliographical synthesis on the microstructure, the colloidal and rheological characterization of bentonite suspensions with and without polymer/surfactant addition; to lead to a rheological characterization of clay-additive mixtures and to understand the interaction between the clay particles and polymer/surfactants. Different experimental measurements: rheology, particle sizing, and x-ray diffraction were used to study the rheological character of the water-bentonite-anionic additive mixtures (CMC, SDS, xanthane) as well as the nature of the particle-particle interactions and particle-additive. The modeling part led to the adoption of Tiu and Boger's model to predict the thixotropy of the bentonite suspensions without additive. Thus, a new model is proposed with physical parameters for a better correlation of the rheological behavior of the various studied mixtures. (author)
Directory of Open Access Journals (Sweden)
Ramona PIN?OI
Full Text Available In the rheological models used in the mathematical description of the rheological behavior ofconcrete. Plays stiffness modulus variation, tangential effort, apparent viscosity, friction angle.
The Deflocculation of Kaolin Suspensions � the Effect of Various Electrolytes
Pe?nkavova?, Ve?ra
The deflocculation effect of conventional additives to kaolin suspensions is evaluated from the results standard rheological measurements. Several widely used electrolytes (NaOH, Na2CO3, Na2SiO3, SHMP = sodium hexametaphosphate, and CMC = sodium salts of carboxymethylcellulose) have been tested. The optimal concentrations of these deffloculants, in respect to reaching the maximum reduction of initial suspension viscosity, are found. The stability of deflocculated kaolin suspensions against...
Synthesis, characterization and electrical properties of solid electrolyte for solid oxide fuel cell; Preparacao, caracterizacao e propriedades eletricas de eletrolito solido para celula a combustivel de oxido solido
Energy Technology Data Exchange (ETDEWEB)
Berton, Marco Antonio Coelho; Garcia, Carlos Mario; Matos, Jeferson Hrenechen [Instituto de Tecnologia para o Desenvolvimento (LACTEC), Curitiba, PR (Brazil)], Emails: firstname.lastname@example.com, firstname.lastname@example.com, firstname.lastname@example.com
Solid electrolytes of BaCe{sub 08}Gd{sub O29} were prepared by the polymeric precursor method. X-ray diffraction data shows a single phase with orthorhombic crystalline structure. The densification process was followed by scanning electronic microscopy and apparent density measurements. The apparent density was developed for different temperatures of sintering, reaching > 96% for sintered temperature of 1550 {sup 0}C deg . The electrochemical impedance analysis was development in the temperature of 400-700 deg C, in air atmosphere at 700 deg C a value of 30,6 mS.cm{sup -1} was obtained. The results of conductivity have confirmed the gadolinium doped barium cerate has a great potential for use as solid electrolyte for intermediate temperature solid oxide fuel cell, at experimental controlled conditions. (author)
Molten salt electrolyte separator
Kaun, Thomas D. (New Lenox, IL)
A molten salt electrolyte/separator for battery and related electrochemical systems including a molten electrolyte composition and an electrically insulating solid salt dispersed therein, to provide improved performance at higher current densities and alternate designs through ease of fabrication.
Barra, Giuseppina
The rheology of caramel was determined as a function of processing temperature and hydrocolloid additions. As the processing temperature increased the water content decreased and the caramel viscosity increased. X-ray diffraction showed that although crystalline fat was present, for the most part the sugars were in the amorphous state. The exception was the lowest water content caramel (7.9% water w.w.b.) which had been processed to a temperature of 122�C. This had a small amount of crystall...
Nanoporous polymer electrolyte
Elliott, Brian (Wheat Ridge, CO); Nguyen, Vinh (Wheat Ridge, CO)
A nanoporous polymer electrolyte and methods for making the polymer electrolyte are disclosed. The polymer electrolyte comprises a crosslinked self-assembly of a polymerizable salt surfactant, wherein the crosslinked self-assembly includes nanopores and wherein the crosslinked self-assembly has a conductivity of at least 1.0.times.10.sup.-6 S/cm at 25.degree. C. The method of making a polymer electrolyte comprises providing a polymerizable salt surfactant. The method further comprises crosslinking the polymerizable salt surfactant to form a nanoporous polymer electrolyte.
New polysaccharide-based polymer electrolytes; Nouveaux electrolytes polymeres a base de polysaccharides
Energy Technology Data Exchange (ETDEWEB)
Velasquez-Morales, P.; Le Nest, J.F.; Gandini, A. [Ecole Francaise de Papeterie et des Industries Graphique, 38 - Saint Martin d`Heres (France)
Polysaccharides like cellulose and chitosan are known for their filmic properties. This paper concerns the synthesis and the study of chitosan-based polymer electrolytes. A preliminary work concerns the study of glucosamine reactivity. The poly-condensation of chitosan ethers (obtained by reaction with ethylene oxide or propylene oxide) with bifunctional and monofunctional oligo-ethers leads to the formation of thin lattices (10 {mu}m) having excellent mechanical properties. The presence of grafted polyether chains along the polysaccharide skeleton allows to modify the vitreous transition temperature and the molecular disorder of the system. Two type of polymer electrolytes have been synthesized: electrolytes carrying a dissolved alkaline metal salt and ionomers. The analysis of their thermal, dynamical mechanical, nuclear magnetic relaxation, electrical, and electrochemical properties shows that this new class of polymer electrolytes has the same performances as ethylene poly-oxide based amorphous lattices plus the advantage of having good filmic properties. Abstract only. (J.S.)
Rheology for chemists an introduction
Goodwin, J W
Rheology is primarily concerned with materials: scientific, engineering and everyday products whose mechanical behaviour cannot be described using classical theories. From biological to geological systems, the key to understanding the viscous and elastic behaviour firmly rests in the relationship between the interactions between atoms and molecules and how this controls the structure, and ultimately the physical and mechanical properties. Rheology for Chemists An Introduction takes the reader through the range of rheological ideas without the use of the complex mathematics. The book gives part
Rheology of carbon nanotube dispersions
Huang, Y Y; Terentyev, E M
We report on rheological properties of a dispersion of multi-walled carbon nanotubes in a viscous polymer matrix. Particular attention is paid to the process of nanotubes mixing and dispersion, which we monitor by the rheological signature of the composite. The response of the composite as a function of the dispersion mixing time and conditions indicates that a critical mixing time t* needs to be exceeded to achieve satisfactory dispersion of aggregates, this time being a function of nanotube concentration and the mixing shear stress. At shorter times of shear mixing, tt*, has several universal rheological features; at nanotube concentration above a characteristic value ~2-3wt% the effective elastic gel network is formed, while the low-concentration composite remains a viscous liquid. We use this rheological approach to determine the effects of aging and re-aggregation.
Synthesis and ceramic processing of zirconia alumina composites for application as solid oxide fuel cell electrolytes; Sintese e processamento de compositos de zirconia-alumina para aplicacao como eletrolito em celulas a combustivel de oxido solido
Energy Technology Data Exchange (ETDEWEB)
Garcia, Rafael Henrique Lazzari
The global warmness and the necessity to obtain clean energy from alternative methods than petroleum raises the importance of developing cleaner and more efficient systems of energy generation, among then, the solid oxide fuel cell (SOFC). Cubic stabilized zirconia (CSZ) has been the most studied material as electrolyte in SOFC, due to its ionic conductivity and great stability at operation conditions. However, its low fracture toughness difficulties its application as a thin layer, what could lead to an improvement of cell efficiency. In this sense, the alumina addition in CSZ forms a composite, which can shift its mechanical properties, without compromising its electrical properties. In this work, coprecipitation synthesis route and ceramic processing of zirconia-alumina composites were studied, in order to establish optimum conditions to attain high density, homogeneous microstructure, and better mechanical properties than CSZ, without compromising ionic conductivity. For this purpose, composites containing up to 40 wt % of alumina, in a 9 mol % yttria-stabilized zirconia (9Y-CSZ) matrix were evaluated. In order to optimize the synthesis of the composites, a preliminary study of powder obtaining and processing were carried out, at compositions containing 20 wt % of alumina, in 9Y-CSZ. The ceramic powders were characterized by helium picnometry, X-ray diffraction, scanning electronic microscopy, transmission electronic microscopy, thermogravimetry, differential scanning calorimetry, granulometry by laser diffraction and gas adsorption (BET). The characterization of sinterized compacts were performed by X-ray diffraction, scanning electron microscopy, optical microscopy, density measurements, Vickers indentation and impedance spectroscopy. The obtained results show that the alumina addition, in the 9Y-CSZ matrix powders, raises the specific surface area, promotes deagglomeration of powders and elevates the oxides crystallization temperature, requiring higher energetic thermal treatments to attain high densities. In relation to the sintered products, it was confirmed the excellent homogeneity and crystallinity of microstructure provided by the chosen route, the restriction of grain growth by alumina addition, raise of hardness and fracture toughness, and higher ionic conductivity, even tough a lower bulk conductivity. These results indicate that the addition of 5 wt % alumina in CSZ matrix allows the application of this material as solid oxide fuel cell electrolytes, due to its better fracture toughness and ionic conductivity, compared to yttria-stabilized cubic zirconia ceramics. (author)
Rheological characterization of nuclear waste using falling-ball rheometry
International Nuclear Information System (INIS)
Knowledge of the rheological properties of saturated solutions containing solid particles is very important in nuclear waste management technology. For example, the nuclear waste in the Hanford Site high-level radioactive waste tanks contains strong electrolyte solutions with a high concentration of solids. Previous attempt using rotational viscometers to determine the rheology has shown unusual thixotropic and shear thinning behaviors with a lack of reproducibility. Using falling-ball rheometry, the rheology of the undisturbed simulant may be determined with much better reproducibility. In this study, a well-mixed simulant which has similar chemical composition to the actual waste will be tested. Falling-ball size and density will be varied to get data in a wide range of shear rates. To determine the rheogram, several methods will be tried to match the observed data. Based on these tests, a rheogram can be determined from the model and its best-fit parameters. The simulant shows shear-thinning behavior and a yield stress. This would suggest a H-B model. But when fitting to one of the simulants which showed a very low yield stress, the predictions assuming no yield and assuming yield resulted in no improvement in the fit when assuming yield
Rheological characterization of aged asphalts
International Nuclear Information System (INIS)
The present work shows the rheological properties of the three Colombian asphalts produced in the refineries at Barrancabermeja, Cartagena and Apiay, exposed to the open air during 18 months using a specially designed testing bank. rheological behavior was evaluated using the new specifications of SHRP technology in the Brookfield and DSR rheometers to determine viscosity, shear stress, shear rate, dynamic share modulus and other related variables. The measurements were made using different temperatures and load times
Rheological measurements on cement grouts
International Nuclear Information System (INIS)
This report describes the techniques which have been developed at Winfrith for assessing the rheological properties of cement grouts. A discussion of the theory of rheology and its application to cement is given and the methodology for calibrating a special paddle measuring system for a commercial viscometer is described. The use of the system for determining flow curves, equilibrium viscosity, viscosity as a function of shearing time and structure changes is also discussed. (author)
Synthesis and Characterization of Nafion-SiO2 Composite Membranes as an Electrolyte for Medium Temperature and Low Relative Humidity
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Endang Sulistyowati
Full Text Available The weakness of the Nafion membrane as electrolyte of PEMFC associated with physical properties that is easy to shrink at temperatures above 80�C due to dehydration. Shrinkage will decrease the conductivity and membrane damage. Nafion-SiO2 composite membranes can improve membrane stability. The role of SiO2 in the Nafion clusters is as water absorbent cause the membrane remains wet at high temperatures and low humidity and conductivity remains high. The results showed the content of 2.8 wt% of SiO2 in the Nafion membrane, the conductivity of composite membrane is higher than the pure Nafion membrane that are 0.127 S cm-1 in dry conditions and 0.778 S cm-1 in wet conditions at room temperature. Compared with the pure Nafion membrane conductivity are 0.0661 S cm-1 and 0.448 S cm-1 respectively in dry and wet conditions.
Rheological Modifiers and Wetting Agents
International Nuclear Information System (INIS)
DOE tank waste treatment plants, the Waste Treatment Plant (WTP) at Hanford and Defense Waste Processing Facility (DWPF) at Savannah River, are designed to vitrify radioactive waste slurries for long-term storage. Plant throughput is currently limited by the waste solids loading. To increase waste throughput rates in the plant, an increase in the slurry solids concentration (or conversely, a reduction in the mass fraction of water in the waste) is being considered. However, the present mechanical designs used to mix and transport theses slurries are limited by the rheological properties. This reduction of water results in an increase in rheological properties that challenge plant design and performance. To support this increase in throughput, there is a need to reduce the rheological properties of these waste slurries. The objective of this project is to determine a small set of well-performing and commercially available rheological modifiers that allow control rheological properties of various simulated and actual waste slurries and to understand the physical mechanisms that govern modification of waste rheology. It is estimated that processing at a higher solids concentration will reduce the operating life of these plants by one year for both facilities, representing roughly $1B in lifecycle cost savings. In addition, this research is potentially important to sustainable operations of both WTP and DWPF
Surface rheology and interface stability.
Energy Technology Data Exchange (ETDEWEB)
Yaklin, Melissa A.; Cote, Raymond O.; Moffat, Harry K.; Grillet, Anne Mary; Walker, Lynn; Koehler, Timothy P.; Reichert, Matthew D. (Carnegie Mellon University, Pittsburgh, PA); Castaneda, Jaime N.; Mondy, Lisa Ann; Brooks, Carlton, F.
We have developed a mature laboratory at Sandia to measure interfacial rheology, using a combination of home-built, commercially available, and customized commercial tools. An Interfacial Shear Rheometer (KSV ISR-400) was modified and the software improved to increase sensitivity and reliability. Another shear rheometer, a TA Instruments AR-G2, was equipped with a du Nouey ring, bicone geometry, and a double wall ring. These interfacial attachments were compared to each other and to the ISR. The best results with the AR-G2 were obtained with the du Nouey ring. A Micro-Interfacial Rheometer (MIR) was developed in house to obtain the much higher sensitivity given by a smaller probe. However, it was found to be difficult to apply this technique for highly elastic surfaces. Interfaces also exhibit dilatational rheology when the interface changes area, such as occurs when bubbles grow or shrink. To measure this rheological response we developed a Surface Dilatational Rheometer (SDR), in which changes in surface tension with surface area are measured during the oscillation of the volume of a pendant drop or bubble. All instruments were tested with various surfactant solutions to determine the limitations of each. In addition, foaming capability and foam stability were tested and compared with the rheology data. It was found that there was no clear correlation of surface rheology with foaming/defoaming with different types of surfactants, but, within a family of surfactants, rheology could predict the foam stability. Diffusion of surfactants to the interface and the behavior of polyelectrolytes were two subjects studied with the new equipment. Finally, surface rheological terms were added to a finite element Navier-Stokes solver and preliminary testing of the code completed. Recommendations for improved implementation were given. When completed we plan to use the computations to better interpret the experimental data and account for the effects of the underlying bulk fluid.
Directory of Open Access Journals (Sweden)
Michael J. Simmonds
Full Text Available The flow properties of blood play significant roles in tissue perfusion by contributing to hydrodynamic resistance in blood vessels. These properties are influenced by pathophysiological processes, thereby increasing the clinical relevance of blood rheology information. There is well-established clinical evidence for impaired blood fluidity in humans of advanced age, including enhanced plasma and whole blood viscosity, impaired red blood cell (RBC deformability and enhanced RBC aggregation. Increased plasma fibrinogen concentration is a common finding in many studies owing to the pro-inflammatory condition of aged individuals; this finding of increased fibrinogen concentration explains the higher plasma viscosity and RBC aggregation in elderly subjects. Enhanced oxidant stress in advanced age is also known to contribute to altered blood fluidity, with RBC deformability being an important determinant of blood viscosity. Several studies have shown that physical activity may improve the hemorheological picture in elderly subjects, yet well-designed observational and mechanistic studies are required to determine the specific effects of regular exercise on hemorheological parameters in healthy and older individuals.
Patricio, Pedro; Duarte, Jorge; Januario, Cristina
We investigate the rheology of a fractal network, in the framework of the linear theory of viscoelasticity. We identify each segment of the network with a simple Kelvin-Voigt element, with a well defined equilibrium length. The final structure retains the elastic characteristics of a solid or a gel. By considering a very simple regular self-similar structure of segments in series and in parallel, in 1, 2 or 3 dimensions, we are able to express the viscoelasticity of the network as an effective generalised Kelvin-Voigt model with a power law spectrum of retardation times, $\\phi\\sim\\tau^{\\alpha-1}$. We relate the parameter $\\alpha$ with the fractal dimension of the gel. In some regimes ($0<\\alpha<1$), we recover the weak power law behaviours of the elastic and viscous moduli with the angular frequencies, $G'\\sim G''\\sim w^\\alpha$, that occur in a variety of soft materials, including living cells. In other regimes, we find different and interesting power laws for $G'$ and $G''$.
Stabilized ?-BIMNVOX solid electrolyte: Ethylene glycol�citrate sol�gel synthesis, microwave-assisted calcination, and structural and electrical characterization
International Nuclear Information System (INIS)
Highlights: �?-BIMNVOX was synthesized by ethylene glycol�citrate sol�gel route. �?-BIMNVOX crystallizes by 25-min microwave-assisted calcination. �Smaller particle sizes for microwave calcined BIMNVOX samples. �Best oxide-ion performance for microwave calcined BIMNVOX samples. -- Abstract: Samples of ?-BIMNVOX (Bi2V1?xMnxO5.5?x/2; 0.13 ? x ? 0.20) system were synthesized by an ethylene glycol�citrate sol�gel route. The resulting xerogels were then calcined by the microwave heating using a modified domestic microwave oven operated at 2.45 GHz. Microwave-assisted calcination samples in comparison with other conventionally calcined samples were characterized in terms of phase crystallization, stabilization and particle size using simultaneous thermogravimetric�differential thermal analysis (TG�DTA), X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM). The AC impedance spectroscopy was employed for electrical characterization. It was found that the microwave-assisted calcination route successfully produces better crystalline stabilized ?-BIMNVOX samples with appreciably small average particle sizes after only 25 min of microwave heating. The electrical properties of microwave calcined ?-BIMNVOX system make it an advanced low-temperature solid electrolyte suitable for use in oxide-ion based electrochemical applications
Gel-combustion synthesis of LiFePO4/C composite with improved capacity retention in aerated aqueous electrolyte solution
International Nuclear Information System (INIS)
Highlights: ? Gel combustion route was used to prepare LiFePO4/C composite with high carbon content ? Theoretical discharge capacity was achieved in non-aqueous medium at rate 0.1 C ? Best so far reported capacity retention in aqueous electrolyte was achieved ? Thick C shell seems to be of crucial importance for LiFePO4 in aqueous media. -- Abstract: The LiFePO4/C composite containing 13.4 wt.% of carbon was synthesized by combustion of a metal salt�(glycine + malonic acid) gel, followed by an isothermal heat-treatment of combustion product at 750 �C in reducing atmosphere. By a brief test in 1 M LiClO4�propylene carbonate solution at a rate of C/10, the discharge capacity was proven to be equal to the theoretical one. In aqueous LiNO3 solution equilibrated with air, at a rate C/3, initial discharge capacity of 106 mAh g?1 was measured, being among the highest ones observed for various Li-ion intercalation materials in aqueous solutions. In addition, significant prolongation of cycle life was achieved, illustrated by the fact that upon 120 charging/discharging cycles at various rates, the capacity remained as high as 80% of initial value. The chemical diffusion coefficient of lithium in this composite was measured by cyclic voltammetry. The obtained values were compared to the existing literature data, and the reasons of high scatter of reported values were considered
Synthesis of 8YSZ-LSGM Composite Thick Film Ceramics for Solid Electrolyte From Nanopowder Utilizing Local Zircon Prepared Using Sol Gel Process
International Nuclear Information System (INIS)
Thick film ceramics of 8% mol Y2O3 doped-ZrO2(8YSZ)-La0.8Sr0.2Ga0.2Mg0.8O3(LSGM) composite for solid electrolyte have been synthesized from nanopowder. Concentration of LSGM was 0 and 10% weight. A paste for the thick films was made from 8YSZ nanopowder prepared using sol gel method and LSGM powder prepared by solid state reaction. Precursors for the 8YSZ nanopowder preparation were ZrOCl2�8H2O derived from local zircon as byproduct of Tin processing at Bangka Island using caustic fusion method, and Y(NO3)3. The thick films were produced by screen printing technique on alumina substrates. The films were sintered at 1500 deg. C for 2 hours in air. X-ray diffraction (XRD) data showed that the nanopowder of 8YSZ was well produced with broad peaks. The particle size of the 8YSZ powder was about 12 nm as calculated using Debye Scherrer method. The thick films of 8YSZ and 8YSZ-LSGM (90:10 in weight %) composite could be produced, however, the films still contain voids. The ionic conductance of the YSZ-10LSGM films was smaller than that of the YSZ films.
A facile synthesis of high quality nanostructured CeO2 and Gd2O3-doped CeO2 solid electrolytes for improved electrochemical performance.
Kuo, Yu-Lin; Su, Yu-Ming; Chou, Hung-Lung
This study describes the use of a composite nitrate salt solution as a precursor to synthesize CeO2 and Gd2O3-doped CeO2 (GDC) nanoparticles (NPs) using an atmospheric pressure plasma jet (APPJ). The microstructures of CeO2 and GDC NPs were found to be cubical and spherical shaped nanocrystallites with average particle sizes of 10.5 and 6.7 nm, respectively. Reactive oxygen species, detected by optical emission spectroscopy (OES), are believed to be the major oxidative agents for the formation of oxide materials in the APPJ process. Based on the material characterization and OES observations, the study effectively demonstrated the feasibility of preparing well-crystallized GDC NPs by the APPJ system as well as the gas-to-particle mechanism. Notably, the Bader charge of CeO2 and Ce0.9Gd0.1O2 characterized by density function theory (DFT) simulation and AC impedance measurements shows that Gd helps in increasing the charge on Ce0.9Gd0.1O2 NPs, thus improving their conductivity and making them candidate materials for electrolytes in solid oxide fuel cells. PMID:25959436
Dry granular flows: rheological measurements of the I-Rheology
Fall, Abdoulaye; Hautemayou, David; M�zi�re, C�dric; Roux, Jean-No�l; Chevoir, Fran�ois
Granular materials do not flow homogeneously like fluids when submitted to external stress,but often form rigid regions that are separated by narrow shear bands where the material yields and flows. This shear localization impacts their apparent rheology, which makes it difficult to infer a constitutive behaviour from conventional rheometric measurements. Moreover, they present a dilatant behaviour, which makes their study in classical fixedvolume geometries difficult. These features led to perform extensive studies with inclined plane flows, which were of crucial importance for the development and the validation of the $\\mu(I)$ rheology. Our aim is to develop a method to characterize granular materials with rheometrical tools. Using unusual rheometry measurements in an annular shear cell adapted from Boyer et al. (2011), dense granular flows are studied. A focus is placed on the comparison between the present results and the I-rheology.
Sol-Gel Synthesis and Conductivity Properties of Sodium Ion Solid State Electrolytes Na3Zr2Si2PO12
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ZHANG Zhi-Zhen, SHI Si-Qi, HU Yong-Sheng, CHEN Li-Quan
Full Text Available NASICON-structured Na3Zr2Si2PO12 was synthesized by a Sol-Gel approach. Phase-pure samples were successfully sintered at 1050? when adding 10% excessive Na and P in the precursors, while a small amount of ZrO2 impurity was detected without adding excessive phosphorus. Electrochemical impedance spectrum tests indicate that the ionic conductivity of the former is as high as 5.4�10-4 S/cm at room temperature, which is higher than that of samples prepared from the precursors without adding excessive phosphorus (3.7�10-4 S/cm. Further analysis reveals that the evaporation of phosphorus at high temperature would cause the formation of ZrO2 impurity in the samples, leading to a lower ionic conductivity. Compared with solid state reaction approach, samples with enhanced ionic conductivity can be obtained at a rather lower temperature by Sol-Gel synthesis.
Hybrid inorganic-organic polymer electrolytes: synthesis, FT-Raman studies and conductivity of {Zr[(CH2CH2O)8.7]?/(LiClO4)z}n network complexes
International Nuclear Information System (INIS)
This paper describes the synthesis and characterization of three-dimensional hybrid inorganic-organic networks prepared by a polycondensation reaction between Zr(O(CH2)3CH3)4 and polyethylene glycol 400 (PEG400). Eleven hybrid networks doped with varying concentrations of LiClO4 salt were prepared. On the basis of analytical data and FT-Raman studies it was concluded that these polymer electrolytes consist of inorganic-organic networks with zirconium atoms bonded together by PEG400 bridges. These polymers are transparent with a solid rubber consistency and are very stable under inert atmosphere. Scanning electron microscopy revealed a smooth glassy surface. X-ray fluorescence microanalysis with energy dispersive spectroscopy demonstrated that all the constituent elements are homogeneously distributed in the materials. Thermogravimetric measurements revealed that these materials are thermally stable up to 262 deg. C. Differential Scanning Calorimetry measurements indicated that the glass transition temperature Tg of these inorganic-organic hybrids varies from -43 to -15 deg. C with increasing LiClO4 concentration. FT-Raman investigations revealed the TGT (T=trans, G=gauche) conformation of polyether chains and allowed characterization of the types of ion-ion and ion-polymer host interactions in the bulk materials. The conductivity of the materials at different temperatures was determined by imifferent temperatures was determined by impedance spectroscopy over the 20 Hz-1 MHz frequency range. Results indicated that the materials conduct ionically and that their ionic conductivity is strongly influenced by the segmental motion of the polymer network and the type of ionic species distributed in the bulk material. Finally, it is to be highlighted that the hybrid network with a nLi/nO molar ratio of 0.0223 shows a conductivity of ca. 1x10-5 S cm-1 at 40 deg. C
Applied Rheology for Polymer Modification
Machado, Ana Vera; Antunes, Carla Filipa; van Duin, Martin
EPDM and EPM were modified using different processing conditions and amounts of peroxide. Rheological measurements were performed in other to characterize and follow the reactions that took place during processing (branching/crosslinking and/or degradation). The experimental results evidenced that branching/crosslinking occurs for EPDM and degradation is the main reaction for EPM.
Anion exchange polymer electrolytes
Energy Technology Data Exchange (ETDEWEB)
Kim, Yu Seung; Kim, Dae Sik
Anion exchange polymer electrolytes that include guanidinium functionalized polymers may be used as membranes and binders for electrocatalysts in preparation of anodes for electrochemical cells such as solid alkaline fuel cells.
International Nuclear Information System (INIS)
An extensive study of hydrogen supply has recently been carried out by Ontario Hydro which indicates that electrolytic hydrogen produced from nuclear electricity could offer the lowest cost option for any future large scale hydrogen supply in the Province of Ontario, Canada. This paper provides a synopsis of the Ontario Hydro study, a brief overview of the economic factors supporting the study conclusion and discussion of a number of issues concerning the supply of electrolytic hydrogen by electric power utilities
Zirconia ceramic solid electrolytes
International Nuclear Information System (INIS)
Magnesia partially stabilized zirconia ceramic solid electrolytes have been studied for the design of electrochemical transducers for oxygen detection. The main results show that around 3% MgO is the optimum solid solution level for ionic conductivity maximum, 2% alumina addition facilitates densification with no further degradation of the electrical behavior, and that thermal hysteresis of the electrical conductivity in zirconia-magnesia solid electrolytes with alumina additions is due in part to the decrease in cubic phase content. (author)
Molecular Rheology of Complex Fluids
DEFF Research Database (Denmark)
Huang, Qian
The processing of polymer materials is highly governed by its rheology, and influences the properties of the final product. For example, a recurring problem is instability in extrusion that leads to imperfect plastic parts. The ability to predict and control the rheological behavior of polymer fluids as a function of molecular chemistry has attracted a long history of collaboration between industry and academia. In industrial polymer processes, there is usually a combination of both shear and extensional flows. In some processing operations such as blow molding and fiber spinning, extensional flow is the dominant type of deformation. The polymer molecules experience a significant amount of chain orientation and stretching during these processes. Shear rheology measured by conventional shear rheometers is good at describing chain orientation, whereas extensional rheology gives a good way of inducing chain stretching. Accurate and reliable stress�strain measurements of extensional flow play a crucial role in the understanding of non�linear rheological properties of polymers. However, the non�linear extensional rheology has not been extensively studied. It is known that the rheology of polymer melts is highly sensitive to molecular architecture, but the precise connection between architecture and non�linear rheology is still not fully understood. For example, linear polymer melts have the simplest architecture, but the possible existence of a qualitative difference on extensional steady�state viscosity between melts and solutions is still an open question. Branched polymer melts have more complex molecular structures. A stress maximum during the start�up of uniaxial extensional flow was reported in 1979 for a low�density polyethylene (LDPE) melt. Subsequently observations of a steady stress following a stress maximum were reported for two LDPE melts. However the rheological significance of the stress maximum as well as the existence of steady flow conditions following the maximum is still a matter of some debate. This thesis focuses on the experimental study of extensional rheology of linear and branched polymer melts. We report the stress�strain measurements in extensional flows using a unique Filament Stretching Rheometer (FSR) in controlled strain rate mode and controlled stress mode. Extensional flow is difficult to measure reliably in Laboratory circumstances. In this thesis we first present an updated control scheme that allows us to control the kinematics of polymer melts in an FSR, which is the foundation of our experimental work. Next we investigate four categories of polymer melts from the simplest system to the most complicated system, including 1) the narrow molar mass distribution (NMMD) linear polystyrene melts and solutions; 2) the bidisperse and polydisperse linear polystyrene melts; 3) the NMMD branched polystyrene melts; and 4) the polydisperse branched polyethylene melts. The experimental results are also compared with some developing theoretical models. Finally, to ensure the experimental data is accurate, the measurements from the FSR are compared with the data from some other extensional rheometers as well.
Lithium sulfide compositions for battery electrolyte and battery electrode coatings
Liang, Chengdu; Liu, Zengcai; Fu, Wujun; Lin, Zhan; Dudney, Nancy J; Howe, Jane Y; Rondinone, Adam J
Method of forming lithium-containing electrolytes are provided using wet chemical synthesis. In some examples, the lithium containing electrolytes are composed of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7. The solid electrolyte may be a core shell material. In one embodiment, the core shell material includes a core of lithium sulfide (Li.sub.2S), a first shell of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7, and a second shell including one of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7 and carbon. The lithium containing electrolytes may be incorporated into wet cell batteries or solid state batteries.
Toughness of membranes applied in polymer electrolyte fuel cells
Energy Technology Data Exchange (ETDEWEB)
Kiefer, J.; Brack, H.P.; Scherer, G.G. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)
Since several years we apply the radiation-grafting technique to prepare polymeric membranes for application in polymer electrolyte fuel cells (PEFCs). Our investigations presented here focus on changes in toughness of these materials after the various synthesis steps and the importance of membrane toughness for their application in PEFCs. (author) 2 figs., 4 refs.
Design of Hybrid Solid Polymer Electrolytes: Structure and Properties
Bronstein, Lyudmila M.; Karlinsey, Robert L.; Ritter, Kyle; Joo, Chan Gyu; Stein, Barry; Zwanziger, Josef W.
This paper reports synthesis, structure, and properties of novel hybrid solid polymer electrolytes (SPE's) consisting of organically modified aluminosilica (OM-ALSi), formed within a poly(ethylene oxide)-in-salt (Li triflate) phase. To alter the structure and properties we fused functionalized silanes containing poly(ethylene oxide) (PEO) tails or CN groups.
Energy Technology Data Exchange (ETDEWEB)
Hansen, E.
The overall objective of the EM-31 Rheological Modifiers and Wetting Agents program is to utilize commercially available rheology modifiers to increase the solids fraction of radioactive sludge based waste streams, resulting in an increase in throughput and decreasing the overall processing time. The program first investigates the impact of rheology modifiers on slurry simulants and then utilizes the most effective rheology modifiers on radioactive slurries. The work presented in this document covers the initial investigation of rheology modifier testing with simulants. This task is supported by both the Savannah River National Laboratory (SRNL) and Pacific Northwest National Laboratory (PNNL). The SRNL EM-31 task, for this year, was to investigate the use of rheology modifiers on simulant Defense Waste Processing Facility (DWPF) melter feeds. The task is to determine, based on the impact of the rheology modifier, if there are rheology modifiers that could reduce the water content of the slurry going to the DWPF melter, hence increasing the melt rate by decreasing the water loading. The rheology modifier in essence would allow a higher solids content slurry to have the same type of rheology or pumpability of a lower solids slurry. The modifiers selected in this report were determined based on previous modifiers used in high level waste melter feed simulants, on-going testing performed by counterparts at PNNL, and experiences gain through use of modifiers in other Department of Energy (DOE) processes such as grout processing. There were 12 rheology modifiers selected for testing, covering both organic and inorganic types and they were tested at four different concentrations for a given melter feed. Five different DWPF melter feeds were available and there was adequate material in one of the melter feeds to increase the solids concentration, resulting in a total of six simulants for testing. The mass of melter feed available in each simulant was not adequate for testing each rheology modifier, hence based on the changes in rheology for a given rheology modifier, rheology modifiers were either dropped or added between simulants. Three rheology modifiers were used on all simulants. The results from this testing indicate that citric acid or polycarboxylate based rheology modifiers are the most effective in reducing the yield stress, by as much as 70% at the higher rheology modifier additions and were effective on most of the tested simulants. These rheology modifiers are organic, hence the can also be used as reductants in melter operations. The most effective non-organic rheology modifiers, sodium metasilicate reduced the yield stress by 10%. It is recommended that both citric acid and commercially available polycarboxylate rheology modifiers be further investigated. Different molecular weight polycarboxylates and different types of polycarboxylates used in other industries must be considered. These polycarboxylates are extensively utilized in the cement, ceramic, and water treatment processes, hence readily available. Future work on DWPF melter feeds involving rheology modifiers should include, assuming the present method of processing sludge through DPWF does not change, is: (1) Investigate the use of polycarboxylate in various processes and procure polycarboxylates for testing. Limit rheology modifier selection and future testing between four and eight different types. (2) Test rheology modifiers on at least two different chemical types or bounding DWPF SME product simulants. Test to include the impact of boiling and the effectiveness in reducing water content via rheology versus weight percent curves. (3) Based on selected modifiers, perform testing on actual radioactive melter feed based on results from simulant testing.
Lithium dendrite growth through solid polymer electrolyte membranes
Harry, Katherine; Schauser, Nicole; Balsara, Nitash
Replacing the graphite-based anode in current batteries with a lithium foil will result in a qualitative increase in the energy density of lithium batteries. The primary reason for not adopting lithium-foil anodes is the formation of dendrites during cell charging. In this study, stop-motion X-ray microtomography experiments were used to directly monitor the growth of lithium dendrites during electrochemical cycling of symmetric lithium-lithium cells with a block copolymer electrolyte. In an attempt to understand the relationship between viscoelastic properties of the electrolyte on dendrite formation, a series of complementary experiments including cell cycling, tomography, ac impedance, and rheology, were conducted above and below the glass transition temperature of the non-conducting poly(styrene) block; the conducting phase is a mixture of rubbery poly(ethylene oxide) and a lithium salt. The tomography experiments enable quantification of the evolution of strain in the block copolymer electrolyte. Our work provides fundamental insight into the dynamics of electrochemical deposition of metallic films in contact with high modulus polymer electrolytes. Rational approaches for slowing down and, perhaps, eliminating dendrite growth are proposed.
Rheology and stability of water-in-oil-in-water multiple emulsions containing Span 83 and Tween 80
Jiao, Jim; Burgess, Diane J.
Multiple emulsions are often stabilized using a combination of hydrophilic and hydrophobic surfactants. The ratio of these surfactants is important in achieving stable multiple emulsions. The objective of this study was to evaluate the long-term stability of water-in-oil-in-water (W/O/W) multiple emulsions with respect to the concentrations of Span 83 and Tween 80. In addition, the effect of surfactant and electrolyte concentration on emulsion bulk rheological properties was investigated. Lig...
Rheology of supersaturated sucrose solutions
Quintas, M.; Branda?o, T. R. S.; Silva, C. L. M.; Cunha, R. L.
Sucrose solutions, with concentrations near or superior to saturation, present high potentialities for the candy and pastry industries. Creep measurements under small stresses were done to obtain the rheological properties of highly concentrated sucrose solutions, since such solutions could be in a metastable state and tend to crystallise. The viscosities of these solutions, from 70.0% to 85.2% (w/w), were determined experimentally at different temperatures, from 0 to 90 C. The temp...
Camelia Vizireanu; Aurelia Ionescu; Daniela Istrati; Felicia Dima
The increased social and economic importance of ready�made food production, together with the complexity of production technology, processing, handling and acceptance of these fragile and perishable products requires extensive knowledge of their physical properties. Viscoelastic properties play an important role in the handling and quality attributes of creams.Our study was to investigate the rheological properties of different confectionary creams, by scanning the field of shear rates at c...
Blood rheology in lupus erythematosus.
Ernst, E.; Hein, A.; Meurer, M; Ruzicka, T
Blood rheology is one of the determinants of perfusion and might therefore have an impact on the thromboembolic complications of lupus erythematosus. This study aimed at defining the flow properties of blood in patients with various types of lupus erythematosus. Results for 51 patients were compared with those for 20 controls matched for sex. The patients were divided into subgroups--chronic discoid, subacute cutaneous, and systemic lupus erythematosus--according to their clinical or laborato...
Nanis, L.; Saunders, A. P.
Foam structure feeds fuel gas solution into electrolyte. Fuel gas reacts at static, three-phase interface between fuel gas, electrolyte, and electrode material. The foam forms an electrical contact between main body of electrolyte and the electrode, and aids in removal of by-products of the chemical reaction.
Magnetic electrolyte destratification
Energy Technology Data Exchange (ETDEWEB)
Newill, W.J.
An electric storage battery including a magnetohydrodynamic pump between the active cell element and the container wall wherein the pump comprises a conduit magnet means for establishing a magnetic field transverse the conduit and electrode means for passing current transverse the field and the conduit to effect movement of electrolyte through the conduit.
Electrolytic production of praseodymium
International Nuclear Information System (INIS)
A method is described for preparing praseodymium metal by electrolyzing praseodymium oxide in a molten electrolyte comprising lithium fluoride and praseodymium fluoride, wherein an initial weight ratio of lithium fluoride to praseodymium fluoride is about 0.1 to about 0.4 and collecting the praseodymium metal at temperatures at or above the melting point of the metal
Conductance of strong electrolytes
International Nuclear Information System (INIS)
An introduction to the theory of strong electrolytes is presented. The derivation of Onsager's limiting law is presented and five empirical and theoretical conductance equations are given. These are compared with measurements by Chiu and Fouss on KCl and NaCl. APL programs for computing the conductivity from the different equations are listed
Gel polymer electrolytes for batteries
Balsara, Nitash Pervez; Eitouni, Hany Basam; Gur, Ilan; Singh, Mohit; Hudson, William
Nanostructured gel polymer electrolytes that have both high ionic conductivity and high mechanical strength are disclosed. The electrolytes have at least two domains--one domain contains an ionically-conductive gel polymer and the other domain contains a rigid polymer that provides structure for the electrolyte. The domains are formed by block copolymers. The first block provides a polymer matrix that may or may not be conductive on by itself, but that can soak up a liquid electrolyte, thereby making a gel. An exemplary nanostructured gel polymer electrolyte has an ionic conductivity of at least 1.times.10.sup.-4 S cm.sup.-1 at 25.degree. C.
Chocolate rheology / Reologia de chocolate
Scientific Electronic Library Online (English)
Estela Vidal, Gon�alves; Suzana Caetano da Silva, Lannes.
Full Text Available Reologia � a ci�ncia que estuda a deforma��o e fluxo de s�lidos e fluidos sob a influ�ncia de for�as mec�nicas. As determina��es reol�gicas de um produto no est�gio de produ��o podem ser �teis no controle de qualidade. A microestrutura de um produto pode ser correlacionada com o comportamento reol�g [...] ico, permitindo desenvolver novos materiais. A reometria permite a aplica��o de equa��es reol�gicas em processos de engenharia, particularmente nas opera��es unit�rias que envolvem aquecimento e transfer�ncia de massa. A demanda dos consumidores torna poss�vel obter um produto que esteja de acordo com as necessidades. As ind�strias de chocolates trabalham com o produto na fase l�quida na concha, na temperadeira e tamb�m durante o bombeamento. O desenho de cada tipo de equipamento � essencial para o �timo processamento. No desenho de cada processo � necess�rio conhecer as caracter�sticas f�sicas do produto. O comportamento reol�gico do chocolate pode auxiliar no conhecimento das caracter�sticas de aplica��o e dos consumidores do produto. Alimentos est�o geralmente em estado metaest�vel. Sua textura depende das trocas estruturais que ocorrem com seu processamento. Chocolate l�quido � uma suspens�o com propriedades que s�o fortemente afetadas pelas caracter�sticas das part�culas, incluindo n�o somente part�culas dispersas mas tamb�m cristais de gordura formados durante o resfriamento e solidifica��o. A reologia de chocolates � extensivamente estudada, a textura do chocolate e sua estabilidade s�o fortemente afetadas pela presen�a de cristais espec�ficos Abstract in english Rheology is the science that studies the deformation and flow of solids and fluids under the influence of mechanical forces. The rheological measures of a product in the stage of manufacture can be useful in quality control. The microstructure of a product can also be correlated with its rheological [...] behavior allowing for the development of new materials. Rheometry permits attainment of rheological equations applied in process engineering, particularly unit operations that involve heat and mass transfer. Consumer demands make it possible to obtain a product that complies with these requirements. Chocolate industries work with products in a liquid phase in conching, tempering, and also during pumping operations. A good design of each type of equipment is essential for optimum processing. In the design of every process, it is necessary to know the physical characteristics of the product. The rheological behavior of chocolate can help to know the characteristics of application of the product and its consumers. Foods are generally in a metastable state. Their texture depends on the structural changes that occur during processing. Molten chocolate is a suspension with properties that are strongly affected by particle characteristics including not only the dispersed particles but also the fat crystals formed during chocolate cooling and solidification. Chocolate rheology is extensively studied, and it is known that chocolate texture and stability is strongly affected by the presence of specific crystals
Chocolate rheology Reologia de chocolate
Directory of Open Access Journals (Sweden)
Estela Vidal Gon�alves
Full Text Available Rheology is the science that studies the deformation and flow of solids and fluids under the influence of mechanical forces. The rheological measures of a product in the stage of manufacture can be useful in quality control. The microstructure of a product can also be correlated with its rheological behavior allowing for the development of new materials. Rheometry permits attainment of rheological equations applied in process engineering, particularly unit operations that involve heat and mass transfer. Consumer demands make it possible to obtain a product that complies with these requirements. Chocolate industries work with products in a liquid phase in conching, tempering, and also during pumping operations. A good design of each type of equipment is essential for optimum processing. In the design of every process, it is necessary to know the physical characteristics of the product. The rheological behavior of chocolate can help to know the characteristics of application of the product and its consumers. Foods are generally in a metastable state. Their texture depends on the structural changes that occur during processing. Molten chocolate is a suspension with properties that are strongly affected by particle characteristics including not only the dispersed particles but also the fat crystals formed during chocolate cooling and solidification. Chocolate rheology is extensively studied, and it is known that chocolate texture and stability is strongly affected by the presence of specific crystalsReologia � a ci�ncia que estuda a deforma��o e fluxo de s�lidos e fluidos sob a influ�ncia de for�as mec�nicas. As determina��es reol�gicas de um produto no est�gio de produ��o podem ser �teis no controle de qualidade. A microestrutura de um produto pode ser correlacionada com o comportamento reol�gico, permitindo desenvolver novos materiais. A reometria permite a aplica��o de equa��es reol�gicas em processos de engenharia, particularmente nas opera��es unit�rias que envolvem aquecimento e transfer�ncia de massa. A demanda dos consumidores torna poss�vel obter um produto que esteja de acordo com as necessidades. As ind�strias de chocolates trabalham com o produto na fase l�quida na concha, na temperadeira e tamb�m durante o bombeamento. O desenho de cada tipo de equipamento � essencial para o �timo processamento. No desenho de cada processo � necess�rio conhecer as caracter�sticas f�sicas do produto. O comportamento reol�gico do chocolate pode auxiliar no conhecimento das caracter�sticas de aplica��o e dos consumidores do produto. Alimentos est�o geralmente em estado metaest�vel. Sua textura depende das trocas estruturais que ocorrem com seu processamento. Chocolate l�quido � uma suspens�o com propriedades que s�o fortemente afetadas pelas caracter�sticas das part�culas, incluindo n�o somente part�culas dispersas mas tamb�m cristais de gordura formados durante o resfriamento e solidifica��o. A reologia de chocolates � extensivamente estudada, a textura do chocolate e sua estabilidade s�o fortemente afetadas pela presen�a de cristais espec�ficos
Rheology of unstable mineral emulsions
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Sokolovi? Dunja S.
Full Text Available In this paper, the rheology of mineral oils and their unstable water emulsion were investigated. The oil samples were domestic crude oil UA, its fractions UA1, UA4 and blend semi-product UP1, while the concentration of oil in water emulsions was in the range from 1 up to 30%. The results were analyzed based on shear stress. The oil samples UA, UA1 and UP1 are Newtonian fluids, while UA4 is pseudoplastic fluid. The samples UA and UA4 show higher value of shear stress (83.75 Pa, 297 Pa, then other two samples UA1 and UP1 (18.41 Pa, 17.52 Pa. Rheology of investigated oils due to its complex chemical composition should be analyzed as a simultaneous effect of all their components. Therefore, structural composition of the oils was determined, namely content of paraffins, naphthenes, aromatics and asphaltenes. All samples contain paraffins, naphthenes and aromatics but only oils UA and UA4 contain asphaltenes as well. All investigated emulsions except 30% EUA4 are Newtonian fluids. The EUA4 30% emulsion shows pseudoplastic behaviour, and it is the only 30% emulsion among investigated ones that achieves lower shear stress then its oil. The characteristics of oil samples that could have an influence on their properties and their emulsion rheology, were determined. These characteristics are: neutralization number, interfacial tension, dielectric constant, and emulsivity. Oil samples UA and UA4 have significantly higher values of neutralization number, dielectric constants, and emulsivity. The sample UA has the lowest value of interface tension and the greatest emulsivity, indicating that this oil, among all investigated, has the highest preference for building emulsion. This could be the reason why 20% and 30% emulsions of the oil UA achieve the highest shear stress among all investigated emulsions.
Rheological behaviour of lahar flow
Lafarge, N.; Chambon, G.; Thouret, J. C.; Laigle, D.
Lahars are mixtures of water and debris flowing down the flanks of volcanoes. These flows generally occur after heavy rainfalls and carry sediments deposited by volcanic eruptions. They are among the most destructive volcanic phenomena, and were responsible, in the 20th century, for 40% of the fatalities associated with volcanic eruptions worldwide. However, the mechanical behaviour and the propagation of these particular debris flows still remain poorly understood. In the frame of the research project Laharisk, Mount Semeru in Java (Indonesia) was chosen as a test site to monitor lahar activity and flows properties owing to the frequent occurrence of lahars on its flanks during the monsoon rainy period. Two observation stations, situated 510 m apart, were installed in the Curah Lengkong Valley on the southeast flank of Semeru volcano. The relatively straight and box-shaped channel between the two stations represents a natural flume well suited to study the hydraulics of the flows. Both stations are equipped with video cameras, pore-pressure and load sensors, AFM geophones, and one broad-band seismometer to measure the evolution over time of lahar flow height, speed, and discharge. Bucket samples are also directly taken in the flows at regular time-intervals in order to provide sediment concentration and grain-size distribution. The rheological behaviour of the material is studied through laboratory vane tests at constant imposed shear rate conducted on the fine-sized fraction (< 400 �m) of the samples. The flows generally comprise several distinct pulses or 'packets' that can be traced between the two instrumented stations. Each pulse lasts between 5 and 30 minutes. Typical flow heights, peak velocities, and maximum discharges range between 0.5-2 m, 3-6 m.s-1, and 25-250 m3.s-1, respectively. The rheometrical tests indicate a mechanical behaviour of the frictional type, the shear stress being almost independent of the shear rate. In addition, the friction coefficient increases with sediment concentration. At the scale of the flow, the rheology of the material can also be investigated through the relationship between flow height and discharge in control sections. The obtained relationship has the form of a power law, and is also indicative of a frictional mechanical behaviour. Here also, the concentration appears as an important parameter controlling the rheological behavior of flow. Hence, both measurement scales consistently show frictional behaviour depending on the concentration of the lahar flow. The determination of this rheological behaviour constitutes an important step towards the development of efficient numerical simulation tools for lahars.
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Natalia Afanasieva
Full Text Available The present work shows the rheological properties of the three Colombian asphalts produced in the refineries at Barrancabermeja, Cartagena and Apiay, exposed to the open air during 18 months using a specially designed testing bank. Rheological behavior was evaluated using the new specifications of SHRP technology in the Brookfield and DSR rheometers to determine viscosity, Shear Stress, Shear Rate, Dynamic Share Modulus and other related variables. The measurements were made using different temperatures and load times.En el presente trabajo se estudian las propiedades reol�gicas de los tres tipos de asfaltos industriales producidos en Colombia, en las refiner�as de Barrancabermeja, Cartagena y Apiay, despu�s del envejecimiento durante 18 meses en un banco de pruebas al aire libre especialmente dise�ado. La evaluaci�n del comportamiento reol�gico se realiz� a trav�s de ensayos basados en las nuevas especificaciones de la tecnolog�a SHRP en los re�metros Brookfield y DSR para determinar caracter�sticas tales como: viscosidad, esfuerzo de corte, susceptibilidad t�rmica, velocidad de deformaci�n y m�dulo de corte din�mico, a diferentes temperaturas y tiempos de carga.
Scientific Electronic Library Online (English)
Natalia, Afanasieva; Mario, �lvarez; M�nica J., Ortiz.
Full Text Available En el presente trabajo se estudian las propiedades reol�gicas de los tres tipos de asfaltos industriales producidos en Colombia, en las refiner�as de Barrancabermeja, Cartagena y Apiay, despu�s del envejecimiento durante 18 meses en un banco de pruebas al aire libre especialmente dise�ado. La evalua [...] ci�n del comportamiento reol�gico se realiz� a trav�s de ensayos basados en las nuevas especificaciones de la tecnolog�a SHRP en los re�metros Brookfield y DSR para determinar caracter�sticas tales como: viscosidad, esfuerzo de corte, susceptibilidad t�rmica, velocidad de deformaci�n y m�dulo de corte din�mico, a diferentes temperaturas y tiempos de carga. Abstract in english The present work shows the rheological properties of the three Colombian asphalts produced in the refineries at Barrancabermeja, Cartagena and Apiay, exposed to the open air during 18 months using a specially designed testing bank. Rheological behavior was evaluated using the new specifications of S [...] HRP technology in the Brookfield and DSR rheometers to determine viscosity, Shear Stress, Shear Rate, Dynamic Share Modulus and other related variables. The measurements were made using different temperatures and load times.
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Camelia Vizireanu
Full Text Available The increased social and economic importance of ready�made food production, together with the complexity of production technology, processing, handling and acceptance of these fragile and perishable products requires extensive knowledge of their physical properties. Viscoelastic properties play an important role in the handling and quality attributes of creams.Our study was to investigate the rheological properties of different confectionary creams, by scanning the field of shear rates at constant temperature and frequency, angular frequency scanning at small deformations and quantification of rheological changes during application of deformation voltages. The creams tested were made in the laboratory using specific concentrates as fine powders, marketed by the company �Dr. Oetker� compared with similar creams based on traditional recipes and techniques. Following the researches conducted we could conclude that both traditional creams and the instant ones are semi fluid food products with pseudoplastic and thixotropic shear flow behavior, with structural viscosity. Instant and traditional creams behaved as physical gels with links susceptible to destruction, when subjected to deformation forces.
Rheological behaviour of reconstructed skin.
Pailler-Mattei, C; Laqui�ze, L; Debret, R; Tupin, S; Aimond, G; Sommer, P; Zahouani, H
Reconstructed skins have been developed to replace skin when the integrity of tissue has been compromised following severe injury, and to provide alternative methods validating the innocuousness and effectiveness of dermatological and cosmetic products. However the functional properties of tissue substitutes have not been well characterised, mainly since mechanical measurement devices have not been designed to test cell culture materials in vitro. From the mechanical standpoint, reconstructed skin is a heterogeneous multi-layer viscoelastic material. To characterise the time-dependent behaviour of reconstructed skin, spherical indentation load-relaxation tests were performed with a specific original device adapted to measure small soft tissue samples. Load-relaxation indentation tests were performed on a standard reconstructed skin model and on sub-components of the reconstructed skin (3D-scaffold alone and dermal equivalent). Generalised Maxwell and Kelvin-Voigt rheological models are proposed for analysing the mechanical behaviour of each biological tissue. The results indicated a modification of the rheological behaviour of the samples tested as a function of their biological structure. The 3D-scaffold was modelled using the one-branch Maxwell model, while the dermis equivalent and the reconstructed skin were modeled using a one-branch and a two-branch Kelvin-Voigt model, respectively. Finally, we demonstrated that skin cells contribute to global mechanical behaviour through an increase of the instantaneous relaxation function, while the 3D-scaffold alone influences the mechanical response of long relaxation times. PMID:24956159
Blood rheology in marine mammals
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Full Text Available The field of blood oxygen transport and delivery to tissues has been studied by comparative physiologists for many decades. Within this general area, the particular differences in oxygen delivery between marine and terrestrial mammals has focused mainly on oxygen supply differences and delivery to the tissues under low blood flow diving conditions. Yet, the study of the inherent flow properties of the blood itself (hemorheology is rarely discussed when addressing diving. However, hemorheology is important to the study of marine mammals because of the critical nature of the oxygen stores that are carried in the blood during diving periods. This review focuses on the essential elements of hemorheology, how they are defined and on fundamental rheological applications to marine mammals. While the comparative rationale used throughout the review is much broader than the particular problems associated with diving, the basic concepts focus on how changes in the flow properties of whole blood would be critical to oxygen delivery during diving. This review introduces the reader to most of the major rheological concepts that are relevant to the unique and unusual aspects of the diving physiology of marine mammals.
Transportable electrolytic decontaminating device
International Nuclear Information System (INIS)
This invention concerns an electrolytic decontaminating device suitable to decontamination of wall surfaces. Annular packaging and tubular electrode are fitted into grooves disposed around the recess of a main body in a state extended and biased forwardly, and an operation shaft is tilted attached. By making the operation shaft tiltable relative to the main body, an operator can conduct decontaminating operation in his stable attitude since the front surface of the main body is kept in parallel with the wall surface of an object to be decontaminated. In a case if the main body is slightly slanted relative to the wall surface of the object to be decontaminated, when higher and lower positions of the object are decontaminated, since the packaging is retractable into the main body, the packing can always be in press-contace with the wall surface surely, thereby preventing the liquid electrolyte from leaking out of the main body. (S.T.)
Possibilities of applying rheological measurements in metallurgy
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M. Korolczuk-Hejnak
Full Text Available Purpose: The purpose of this paper is to analyse from the literature point of view the issues concerning modern methods of measuring the viscosity of liquid steel and solid-liquid steel in the course of rheological research with the use of a high temperature rheometer. The paper reviews the subject of measuring and modelling the viscosity value of steel with the use of equations and data available in the literature. It also presents the difficulties connected to rheological measurements of liquid steel and metallurgical slag.Design/methodology/approach: The main purpose of this paper is to present the issues relating to rheological measurements and the possibilities of their application in metallurgy.Findings: The paper describes the issues pertaining to the viscosity measurements of liquid and metallurgical slag.Research limitations/implications: In the future the authors are planning to develop an empirical model which would include rheological parameters and would be used to calculate the viscosity of liquid iron solutions on the basis of conducted rheological measurements of liquid steel.Practical implications: The results of investigation might be used in the future in semi-solid metal (SSM forming. A fundamental and detailed understanding of the steel rheology is crucial for industrialization.Originality/value: The paper presents the issues connected to the subject of and difficulties encountered in the course of rheological measurements of liquid ferroalloys and metallurgical slag.
Comportamento reol�gico de suspens�es aquosas de cromito de lant�nio / Rheological behaviour of lanthanum chromite aqueous suspension
Scientific Electronic Library Online (English)
L. F. G., Setz; I., Santacruz; M. T., Colomer; R., Moreno; S. R. H., Mello-Castanho.
Full Text Available O cromito de lant�nio (LaCrO3) � o material mais estudado para a produ��o de interconectores para c�lulas a combust�vel de �xido s�lido (SOFC). Devido a complexidade das microestruturas e geometrias das SOFCs, freq�entemente s�o necess�rias, t�cnicas de processamento coloidal, os quais t�m recebido [...] maior aten��o nos �ltimos anos por permitirem a obten��o de partes complexas com microestrutura controlada e reprodut�veis. Nos �ltimos anos, muito esfor�o tem sido direcionado ao processamento dos eletr�litos e eletrodos, mas aos componentes como o interconector, pouca aten��o tem sido dada. Este artigo apresenta o estudo reol�gico e de conforma��o em moldes de gesso do cromito de lant�nio para a produ��o de interconectores para SOFCs. A composi��o La0,80Sr0,20Cr0,92Co0,08O3, obtida por rea��o de combust�o, foi utilizada. As suspens�es aquosas foram preparadas com conte�do de s�lidos variando de 8 a 17,5% vol. utilizando-se, poliacrilato de am�nia (PAA) como polieletr�lito/dispersante e hidr�xido de tetrametilam�nio (HTMA) como provedor de alcalinidade. A influ�ncia da concentra��o dos aditivos e o tempo em moinho de bolas foram estudados. Os resultados indicam que o tempo 24 h de homogeneiza��o em moinho de bolas, com 3% e 1%, em massa, de PAA e HTMA respectivamente, proporcionam as melhores condi��es para colagem em moldes de gesso, sendo poss�vel obter pe�as ap�s sinteriza��o com densidades relativas elevadas. Abstract in english Lanthanum chromite (LaCrO3) is the most studied material for SOFC's interconnectors' production. The complexity of microstructures and geometries of SOFC devices often requires the use of colloidal processing techniques, which have received increased attention in the last years for obtaining complex [...] parts with controlled microstructure and high reliability. Much effort has been devoted to the processing of electrodes and electrolytes but the other layers, such as that of interconnecting material, have received scarce attention. This paper deals with the rheology and casting behaviour of lanthanum chromite based materials to produce interconnectors for SOFCs. A powder with the composition La0.80Sr0.20Cr0.92Co0.08O3 was obtained by combustion synthesis. Aqueous suspensions were prepared to solids loading ranging from 8 to 17.5 vol.%, using ammonium polyacrylate (PAA) as polyelectrolyte/dispersant and tetramethylammonium hydroxide (TMAH) to assure basic pH. The influence of the additives concentrations and suspension ball milling time were studied. Suspensions prepared with 24 h ball milling, with 3 wt.% and 1 wt.%, of PAA and TMAH respectively, yielded the best conditions for successful slip casting, leading to relatively dense sintered materials.
Comportamento reol�gico de suspens�es aquosas de cromito de lant�nio Rheological behaviour of lanthanum chromite aqueous suspension
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L. F. G. Setz
Full Text Available O cromito de lant�nio (LaCrO3 � o material mais estudado para a produ��o de interconectores para c�lulas a combust�vel de ??xido s�lido (SOFC. Devido a complexidade das microestruturas e geometrias das SOFCs, freq�entemente s�o necess�rias, t�cnicas de processamento coloidal, os quais t�m recebido maior aten��o nos �ltimos anos por permitirem a obten��o de partes complexas com microestrutura controlada e reprodut�veis. Nos �ltimos anos, muito esfor�o tem sido direcionado ao processamento dos eletr�litos e eletrodos, mas aos componentes como o interconector, pouca aten��o tem sido dada. Este artigo apresenta o estudo reol�gico e de conforma��o em moldes de gesso do cromito de lant�nio para a produ��o de interconectores para SOFCs. A composi��o La0,80Sr0,20Cr0,92Co0,08O3, obtida por rea��o de combust�o, foi utilizada. As suspens�es aquosas foram preparadas com conte�do de s�lidos variando de 8 a 17,5% vol. utilizando-se, poliacrilato de am�nia (PAA como polieletr�lito/dispersante e hidr�xido de tetrametilam�nio (HTMA como provedor de alcalinidade. A influ�ncia da concentra��o dos aditivos e o tempo em moinho de bolas foram estudados. Os resultados indicam que o tempo 24 h de homogeneiza��o em moinho de bolas, com 3% e 1%, em massa, de PAA e HTMA respectivamente, proporcionam as melhores condi��es para colagem em moldes de gesso, sendo poss�vel obter pe�as ap�s sinteriza��o com densidades relativas elevadas.Lanthanum chromite (LaCrO3 is the most studied material for SOFC's interconnectors' production. The complexity of microstructures and geometries of SOFC devices often requires the use of colloidal processing techniques, which have received increased attention in the last years for obtaining complex parts with controlled microstructure and high reliability. Much effort has been devoted to the processing of electrodes and electrolytes but the other layers, such as that of interconnecting material, have received scarce attention. This paper deals with the rheology and casting behaviour of lanthanum chromite based materials to produce interconnectors for SOFCs. A powder with the composition La0.80Sr0.20Cr0.92Co0.08O3 was obtained by combustion synthesis. Aqueous suspensions were prepared to solids loading ranging from 8 to 17.5 vol.%, using ammonium polyacrylate (PAA as polyelectrolyte/dispersant and tetramethylammonium hydroxide (TMAH to assure basic pH. The influence of the additives concentrations and suspension ball milling time were studied. Suspensions prepared with 24 h ball milling, with 3 wt.% and 1 wt.%, of PAA and TMAH respectively, yielded the best conditions for successful slip casting, leading to relatively dense sintered materials.
Directory of Open Access Journals (Sweden)
Mohammad Hojjatoleslamyi
Full Text Available Psyllium (Plantago psyllium is a native plant that grows widely in India, Iran and Pinjab. Studies showed psyllium gum has good rheological properties for using in wide range of food products. In this study, different fractions of psyllium gum extracted by water and alkali treatment. Rheological properties of these fractions determined by Brookfield rheometer (RV DVIII. Obtained data fitted in three temperatures 30, 60 and 80�C by Herschel-bulkly rheological model. Results showed that fractions have different behaviour during heating treatment. The most difference observed in AEG0.5 fraction.
Electrolytes for rechargeable lithium batteries
Venkatasetty, H. V.
Recent advances in the liquid electrolyte area for high-energy lithium cathode systems are reviewed. Experimental work on the processing of solid thin-film polymer electrolytes using plasticizers such as polyethylene glycol dimethoxy ether (PEGDME) and conductivity and differential scanning calorimetry results for polymer film electrolytes are presented. The advantages and the disadvantages of polymer thin-film electrolytes are discussed. It is apparent from these studies that films processed with a plasticizer such as PEGDME show improved conductivity, possibly due to increased amorphous phase content.
Ceramic electrolyte coating and methods
Energy Technology Data Exchange (ETDEWEB)
Seabaugh, Matthew M. (Columbus, OH); Swartz, Scott L. (Columbus, OH); Dawson, William J. (Dublin, OH); McCormick, Buddy E. (Dublin, OH)
Aqueous coating slurries useful in depositing a dense coating of a ceramic electrolyte material (e.g., yttrium-stabilized zirconia) onto a porous substrate of a ceramic electrode material (e.g., lanthanum strontium manganite or nickel/zirconia) and processes for preparing an aqueous suspension of a ceramic electrolyte material and an aqueous spray coating slurry including a ceramic electrolyte material. The invention also includes processes for depositing an aqueous spray coating slurry including a ceramic electrolyte material onto pre-sintered, partially sintered, and unsintered ceramic substrates and products made by this process.
Rheological and textural properties of cosmetic emulsions.
Czech Academy of Sciences Publication Activity Database
Mor�vkov�, Tereza; �tern, Petr
Ro?. 21, ?. 3 (2011), s. 35200. ISSN 1430-6395 Institutional research plan: CEZ:AV0Z20600510 Keywords : cosmetic emulsions * rheology * texture * sensory analysis * psychorheology Subject RIV: BK - Fluid Dynamics Impact factor: 1.000, year: 2011
Electrolytic oxide reduction system
Energy Technology Data Exchange (ETDEWEB)
Wiedmeyer, Stanley G; Barnes, Laurel A; Williamson, Mark A; Willit, James L; Berger, John F
An electrolytic oxide reduction system according to a non-limiting embodiment of the present invention may include a plurality of anode assemblies, a plurality of cathode assemblies, and a lift system configured to engage the anode and cathode assemblies. The cathode assemblies may be alternately arranged with the anode assemblies such that each cathode assembly is flanked by two anode assemblies. The lift system may be configured to selectively engage the anode and cathode assemblies so as to allow the simultaneous lifting of any combination of the anode and cathode assemblies (whether adjacent or non-adjacent).
Electrolyte creepage barrier for liquid electrolyte fuel cells
Li, Jian (Alberta, CA); Farooque, Mohammad (Danbury, CT); Yuh, Chao-Yi (New Milford, CT)
A dielectric assembly for electrically insulating a manifold or other component from a liquid electrolyte fuel cell stack wherein the dielectric assembly includes a substantially impermeable dielectric member over which electrolyte is able to flow and a barrier adjacent the dielectric member and having a porosity of less than 50% and greater than 10% so that the barrier is able to measurably absorb and chemically react with the liquid electrolyte flowing on the dielectric member to form solid products which are stable in the liquid electrolyte. In this way, the barrier inhibits flow or creepage of electrolyte from the dielectric member to the manifold or component to be electrically insulated from the fuel cell stack by the dielectric assembly.
Rheological properties of concentrated alumina slurries: influence of ph and dispersant agent
International Nuclear Information System (INIS)
The relationship between the ph, the electrolyte concentrations and the rheological properties of high concentrated alumina slurries in aqueous medium is of great importance because it is considered to be the key to control the stability of the slurries from flocculation. Zeta potential of alumina slurries with and without Duramax C (dispersant agent) as a function of ph was studied. Two ph around the zero point of charge of alumina slurries were selected for the investigation of rheological properties. The rheological properties of aqueous alumina slurries with respect to different parameters, e.g.: viscosity, elastic modulus (storage modulus G) and viscous modulus (loss modulus G), were investigated. Viscosity measurements of the slurries as a function of Duramax C content at both ph 8.4 and 9.4) were used to determine the state of slurries. Three states of slurries, termed flocculated, partially de flocculated and fully de flocculated, were selected for further investigation. The viscosity of the three slurries at both ph as a function of shear rate was determined. Fully de flocculated slurry shows Newtonian behavior at all shear rates at both tested ph compared by the partial de flocculated and flocculated system. Results of investigation of G and G at ph of 9.4 as a function of applied stress explored the critical stress
PVC paste rheology: Study of process dependencies
Rasteiro, M. G.; Toma?s, A.; Ferreira, L.; Figueiredo, S.
A plastisol is a dispersion (suspension) of fine particles of poly(vinyl chloride) with a plasticizer that is normally applied over a substrate, by spreading or coating, before the gelification and fusion into the final product. Because of the first step, the plastisol rheology study is a very important factor which has to be taken into consideration to determine and fine tune the process conditions. This work is concerned with the study of the rheology of plastisols from selected PVC samp...
Electrolytes - Technology review
International Nuclear Information System (INIS)
Safety, lifetime, energy density, and costs are the key factors for battery development. This generates the need for improved cell chemistries and new, advanced battery materials. The components of an electrolyte are the solvent, in which a conducting salt and additives are dissolved. Each of them plays a specific role in the overall mechanism of a cell: the solvent provides the host medium for ionic conductivity, which originates in the conductive salt. Furthermore, additives can be used to optimize safety, performance, and cyclability. By understanding the tasks of the individual components and their optimum conditions of operation, the functionality of cells can be improved from a holistic point of view. This paper will present the most important technological features and requirements for electrolytes in lithium-ion batteries. The state-of-the-art chemistry of each component is presented, as well as different approaches for their modification. Finally, a comparison of Li-cells with lithium-based technologies currently under development is conducted
Electrolytes - Technology review
Energy Technology Data Exchange (ETDEWEB)
Meutzner, Falk; Ure�a de Vivanco, Mateo [Institut f�r Experimentelle Physik, Technische Universit�t Bergakademie Freiberg, Leipziger Stra�e 23, 09596 Freiberg (Germany)
Safety, lifetime, energy density, and costs are the key factors for battery development. This generates the need for improved cell chemistries and new, advanced battery materials. The components of an electrolyte are the solvent, in which a conducting salt and additives are dissolved. Each of them plays a specific role in the overall mechanism of a cell: the solvent provides the host medium for ionic conductivity, which originates in the conductive salt. Furthermore, additives can be used to optimize safety, performance, and cyclability. By understanding the tasks of the individual components and their optimum conditions of operation, the functionality of cells can be improved from a holistic point of view. This paper will present the most important technological features and requirements for electrolytes in lithium-ion batteries. The state-of-the-art chemistry of each component is presented, as well as different approaches for their modification. Finally, a comparison of Li-cells with lithium-based technologies currently under development is conducted.
Platelet additive solution - electrolytes.
Azuma, Hiroshi; Hirayama, Junichi; Akino, Mitsuaki; Ikeda, Hisami
Recent attention to solutions that replace most or all plasma in platelet concentrates, while maintaining satisfactory platelet function, is motivated by the potential of plasma reduction or depletion to mitigate various transfusion-related adverse events. This report considers the electrolytic composition of previously described platelet additive solutions, in order to draw general conclusions about what is required for platelet function and longevity. The optimal concentrations of Na(+) and Cl(-) are 69-115 mM. The presence of both K(+) and Mg(2+) in platelet suspension at nearly physiological concentrations (3-5mM and 1.5-3mM, respectively) is indispensable for good preservation capacity because both electrolytes are required to prevent platelet activation. In contrast to K(+) and Mg(2+), Ca(2+) may not be important because no free Ca(2+) is available in M-sol, which showed excellent platelet preservation capacity at less than 5% plasma concentration. The importance of bicarbonate (approximately 40 mM) can be recognized when the platelets are suspended in additive solution under less than 5% residual plasma concentration. PMID:21498128
Rheology of welding: Field constraints
Russell, K.; Quane, S.
Pyroclastic deposits emplaced at high temperature and having sufficient thickness become welded via sintering, compaction and flattening of hot glassy particles. The welding process is attended by pronounced changes in the physical properties of the deposit and welding intensity can be tracked by measuring the density, porosity, fabric or strength of samples. Ultimately, the intensity of welding reflects the aggregate effects of load and residence time at temperatures above the glass transition temperature (Tg). This results in welding intensity varying with stratigraphic depth; vertical sections through welded ignimbrite deposits commonly show maximum (e.g., density) or minimum (porosity) values in physical properties in the lower half (30--40% above the base) of the unit. Here we explore the extent to which these data, serving as proxies for strain, can be used constrain the rheological properties of the pyroclastic deposit during the welding process. Our data include measurements of density, porosity, fabric and rock strength as a function of stratigraphic position for 4 sections through the Bandelier tuff, New Mexico. These profiles record changes in physical properties and, thus, map the cumulative strain associated with welding as a function of depth (load). We have used simple conductive heat transfer models to estimate cooling curves for each sample. Essentially, these curves provide the residence time within the "welding window" for each sample. The curves are dependent on sample position, thickness of ignimbrite, emplacement temperature and the glass transition temperature of the material. The unknowns in the problem are a number of physical constants in a generalized power-law relationship between strain-rate (?') and stress (?) for steady-state creep at constant load: ?' = A ?^n e[-Q/R T]. Specifically, we adopt an inverse-model approach whereby the observations on the natural material are used to constrain the pre-exponential constant (A), stress factor (n) and the activation energy (Q) governing the compaction and welding of the ignimbrite. The inversion of the natural dataset for these parameters provides us with a constitutive relationship for the rheology of pyroclastic material as a function of temperature, load and strain rate and can be used to investigate generalities concerning: a) the mechanisms of welding, b) the timescales of welding, or d) the distributions of welding in pyroclastic deposits.
Rheological behavior study of a clay-polymer mixture: effects of the polymer addition; Etude du comportement rheologique de melanges argiles - polymeres. Effets de l'ajout de polymeres
Energy Technology Data Exchange (ETDEWEB)
Benchabane, A
The aim of the present work is to establish a bibliographical synthesis on the microstructure, the colloidal and rheological characterization of bentonite suspensions with and without polymer/surfactant addition; to lead to a rheological characterization of clay-additive mixtures and to understand the interaction between the clay particles and polymer/surfactants. Different experimental measurements: rheology, particle sizing, and x-ray diffraction were used to study the rheological character of the water-bentonite-anionic additive mixtures (CMC, SDS, xanthane) as well as the nature of the particle-particle interactions and particle-additive. The modeling part led to the adoption of Tiu and Boger's model to predict the thixotropy of the bentonite suspensions without additive. Thus, a new model is proposed with physical parameters for a better correlation of the rheological behavior of the various studied mixtures. (author)
Charge relaxation dynamics of an electrolytic nanocapacitor
Thakore, Vaibhav
Understanding ion relaxation dynamics in overlapping electric double layers (EDLs) is critical for the development of efficient nanotechnology based electrochemical energy storage, electrochemomechanical energy conversion and bioelectrochemical sensing devices besides controlled synthesis of nanostructured materials. Here, using Lattice Boltzmann (LB) method, we present results from the simulations of an electrolytic nanocapacitor subjected to a step potential at t = 0 for various degrees of EDL overlap, solvent viscosities, ratios of cation to anion diffusivity and electrode separations. A continuously varying molecular speed dependent relaxation time, proposed for use with the LB equation, recovers the correct microscopic description of molecular collision phenomena and holds promise for enhancing the stability of the LB algorithm. Results for large EDL overlap showed oscillatory behavior for ionic current densities in contrast to monotonic relaxation to equilibrium for low EDL overlap. Further, at low solv...
Rheological Behavior of Oligomeric Ionomers
Energy Technology Data Exchange (ETDEWEB)
Weiss, R.; Zhao, H
The rheological behavior of the alkali metal salts of oligomeric sulfonated polystyrene (PS) ionomers was characterized using dynamic and steady shear measurements. The starting PS had a weight average molecular weight of 4000 g/mol and a narrow molecular weight distribution (1.06). Two sulfonation levels were examined, 2.5 and 4.8 mol %, which corresponded, respectively, to one and two sulfonate groups per chain on average. The ionomers exhibited nanophase separation of an ion-rich phase, and as a consequence, time-temperature superposition failed for all samples. Sulfonation increased the melt viscosity of the ionomers, as much as seven orders of magnitude. The zero shear viscosity scaled as cq/a, where c was the concentration of the ionic groups, q was the charge of the cation, and a was the cation radius, and although the molecular weight of the parent polystyrene was much lower than the entanglement molecular weight, the ionomer melts exhibited strong elastic behavior. The flow activation energy of the ionomers was similar to that of high molecular weight PS and the calculated molecular weight between 'entanglements' of the ionomers was the same as for PS.
Electrolytes and thermoregulation
Nielsen, B.; Greenleaf, J. E.
The influence of ions on temperature is studied for cases where the changes in ionic concentrations are induced by direct infusion or injection of electrolyte solutions into the cerebral ventricles or into specific areas of brain tissue; intravenous infusion or injection; eating food or drinking solutions of different ionic composition; and heat or exercise dehydration. It is shown that introduction of Na(+) and Ca(++) into the cerebral ventricles or into the venous system affects temperature regulation. It appears that the specific action of these ions is different from their osmotic effects. It is unlikely that their action is localized to the thermoregulatory centers in the brain. The infusion experiments demonstrate that the changes in sodium balance occurring during exercise and heat stress are large enough to affect sweat gland function and vasomotor activity.
DEFF Research Database (Denmark)
Bjerrum, Niels Technical University of Denmark,
A method for preparing polybenzimidazole or polybenzimidazole blend membranes and fabricating gas diffusion electrodes and membrane-electrode assemblies is provided for a high temperature polymer electrolyte membrane fuel cell. Blend polymer electrolyte membranes based on PBI and various thermoplastic polymers for high temperature polymer electrolyte fuel cells have also been developed. Miscible blends are used for solution casting of polymer membranes (solid electrolytes). High conductivity and enhanced mechanical strength were obtained for the blend polymer solid electrolytes. With the thermally resistant polymer, e.g., polybenzimidazole or a mixture of polybenzimidazole and other thermoplastics as binder, the carbon-supported noble metal catalyst is tape-cast onto a hydrophobic supporting substrate. When doped with an acid mixture, electrodes are assembled with an acid doped solid electrolyte membrane by hot-press. The fuel cell can operate at temperatures up to at least 200 �C with hydrogen-rich fuel containing high ratios of carbon monoxide such as 3 vol% carbon monoxide or more, compared to the carbon monoxide tolerance of 10-20 ppm level for Nafion$m(3)-based polymer electrolyte fuel cells.
Photopolymerized Electrolytes For Electrochromic Devices
Cogan, Stuart; Rauh, R. David
Thin ion-conducting electrolyte films for use in electrochromic devices now fabricated relatively easily and quickly with any of class of improved formulations containing ultraviolet-polymerizable components. Formulations are liquids in their monomeric forms and self-supporting, transparent solids in their polymeric forms. Thin solid electrolytes form quickly and easily between electrode-bearing substrates. Film thus polymerized acts not only as solid electrolyte but also as glue holding laminate together: feature simplifies fabrication by reducing need for sealants and additional mechanical supports.
Initial rheological description of high performance concretes
Scientific Electronic Library Online (English)
Alessandra Lorenzetti de, Castro; Jefferson Benedicto Libardi, Liborio.
Full Text Available Concrete is defined as a composite material and, in rheological terms, it can be understood as a concentrated suspension of solid particles (aggregates) in a viscous liquid (cement paste). On a macroscopic scale, concrete flows as a liquid. It is known that the rheological behavior of the concrete i [...] s close to that of a Bingham fluid and two rheological parameters regarding its description are needed: yield stress and plastic viscosity. The aim of this paper is to present the initial rheological description of high performance concretes using the modified slump test. According to the results, an increase of yield stress was observed over time, while a slight variation in plastic viscosity was noticed. The incorporation of silica fume showed changes in the rheological properties of fresh concrete. The behavior of these materials also varied with the mixing procedure employed in their production. The addition of superplasticizer meant that there was a large reduction in the mixture's yield stress, while plastic viscosity remained practically constant.
Initial rheological description of high performance concretes
Directory of Open Access Journals (Sweden)
Alessandra Lorenzetti de Castro
Full Text Available Concrete is defined as a composite material and, in rheological terms, it can be understood as a concentrated suspension of solid particles (aggregates in a viscous liquid (cement paste. On a macroscopic scale, concrete flows as a liquid. It is known that the rheological behavior of the concrete is close to that of a Bingham fluid and two rheological parameters regarding its description are needed: yield stress and plastic viscosity. The aim of this paper is to present the initial rheological description of high performance concretes using the modified slump test. According to the results, an increase of yield stress was observed over time, while a slight variation in plastic viscosity was noticed. The incorporation of silica fume showed changes in the rheological properties of fresh concrete. The behavior of these materials also varied with the mixing procedure employed in their production. The addition of superplasticizer meant that there was a large reduction in the mixture's yield stress, while plastic viscosity remained practically constant.
Dramatical Impact Of Low Amounts of Swelling Clays On The Rheology Of Alpine Debris Flows
Bardou, E.; Bowen, P.; Banfill, P. G.; Boivin, P.
Field observations show that the role and amount of swelling clays in the complex hard suspensions of alpine debris flow type were underestimated (see Boivin et al., this session). This work aims at exploring to which extent the swelling clay content influences the global rheology of a flow of rock grains from which the size spectrum extends from clays to gravel. We made a sample from calibrated materials with a grain size distribution similar to that of a viscoplastic debris flow (Bardou et al., 2003). Four replicates were made with the same grading curve. The clay content of the samples was 2% dry weight only, and different 2:1 swelling clay to 1:1 clay ratio were used. The swelling clay ratio (SCR) was calculated as the percentage of 2:1 clay in the clay fraction of the bulk samples. The 1:1 clay was (industrial) kaolinite and the 2:1 clay was a natural soil smectite. The smectite content in the bulk sample ranged from 0% to 2% dry weight, corresponding to SCR ranging from 0 to 80%. The four prepared samples were sheared in the large-size apparatus fully described in Tattersall and Banfill (1983). This apparatus is based on the measure of the torque necessary to rotate an impeller immersed in the sample. The impeller has the form of an "H" and moves in a plane according to two parallel axes. The observed behaviour were very contrasted. The sample with SCR=0 was poorly sensitive to changes in the solid concentration, in contrast to the three samples with SCR>0. Moreover, a small change in the SCR of the clay fraction induced a dramatic change of the behaviour of the mixture. For SCR=0, only little changes in the rheological parameters of the bulk samples were observed with respect to changes in the solid concentration. On the contrary the rheological parameters of the bulk samples with SCR>0, apparently followed a power law according to solid concentration. These tests carried out in the laboratory accord with observations realised on natural debris flow material. Although these results can't be upscaled to a quantitative assessment of the effects of changes in the SCR in a dense granular suspension they have, however, has a direct implications for debris flow rheological studies. Even though weighting for a very little part of the materials, the swelling clays cannot be neglected in the analysis of such mixtures. Moreover, colloid properties of these clays are very sensitive to factors such as electrolyte composition, clay surface coatings and shaking energy. Therefore, the electrolyte used in test the materials, and chemical equilibration time within electrolyte and solid phase, should be carefully selected with respect to field conditions. References Bardou, E., Ancey, C., Bonnard, C. and Vulliet, L., 2003. A typological approach of debris flow useful for hazard assessement in the alpine area. In: D. Rickenmann and C. Cheng-lung (Editors), 3rd DFHM, Davos. Bardou, E., Bowen, P., Boivin, P., Banfill, P.F.G. submitted Effect of the Clay Type on the Rheology of an Heterogeneous Dense Granular Material. Implication for the Study of Alpine Debris Flow. Boivin, P., Bardou E., Pfeifer, H.-R.: Role And Behaviour Of Clay Minerals In Alpine Debris Flows. This session Tattersall, G.H. & Banfill, P.F.G. 1983: The rheology of fresh concrete. Pitman, London.
Rheological Characterization of Unusual DWPF Slurry Samples
International Nuclear Information System (INIS)
A study was undertaken to identify and clarify examples of unusual rheological behavior in Defense Waste Processing Facility (DWPF) simulant slurry samples. Identification was accomplished by reviewing sludge, Sludge Receipt and Adjustment Tank (SRAT) product, and Slurry Mix Evaporator (SME) product simulant rheological results from the prior year. Clarification of unusual rheological behavior was achieved by developing and implementing new measurement techniques. Development of these new methods is covered in a separate report, WSRC-TR-2004-00334. This report includes a review of recent literature on unusual rheological behavior, followed by a summary of the rheological measurement results obtained on a set of unusual simulant samples. Shifts in rheological behavior of slurries as the wt. % total solids changed have been observed in numerous systems. The main finding of the experimental work was that the various unusual DWPF simulant slurry samples exhibit some degree of time dependent behavior. When a given shear rate is applied to a sample, the apparent viscosity of the slurry changes with time rather than remaining constant. These unusual simulant samples are more rheologically complex than Newtonian liquids or more simple slurries, neither of which shows significant time dependence. The study concludes that the unusual rheological behavior that has been observed is being caused by time dependent rheological properties in the slurries being measured. Most of the cthe slurries being measured. Most of the changes are due to the effect of time under shear, but SB3 SME products were also changing properties while stored in sample bottles. The most likely source of this shear-related time dependence for sludge is in the simulant preparation. More than a single source of time dependence was inferred for the simulant SME product slurries based on the range of phenomena observed. Rheological property changes were observed on the time-scale of a single measurement (minutes) as well as on a time scale of hours to weeks. The unusual shape of the slurry flow curves was not an artifact of the rheometric measurement. Adjusting the user-specified parameters in the rheometer measurement jobs can alter the shape of the flow curve of these time dependent samples, but this was not causing the unusual behavior. Variations in the measurement parameters caused the time dependence of a given slurry to manifest at different rates. The premise of the controlled shear rate flow curve measurement is that the dynamic response of the sample to a change in shear rate is nearly instantaneous. When this is the case, the data can be fitted to a time independent rheological equation, such as the Bingham plastic model. In those cases where this does not happen, interpretation of the data is difficult. Fitting time dependent data to time independent rheological equations, such as the Bingham plastic model, is also not appropriate
Structure and Rheology of Concentrated Emulsions
Huang, Jung-Ren; Lai, Yi-Cian; Ou, Che-Hao; Tsai, Jih-Chiang
We construct a shearing apparatus combining light scattering and stress measurement to study the structure and rheology of concentrated monodisperse emulsions. The emulsions are subjected to oscillatory shear of variable amplitude and frequency. The light scattering data reflect droplet deformation as well as shear history-dependent inter-droplet structures. The stress measurements display pseudoplasticity near zero shear rate and shear-thinning behavior at finite shear rates. In addition, the time-resolved, synchronous measurement of light scattering and rheology reveal detailed information about the complex structure-rheology relationship of emulsions. Shear disorders the droplets at low and high shear rates but induces order at medium shear rates. Furthermore, the effective viscosity increases as the degree of inter-droplet order decreases. This work is supported by Taiwan MOST Grant 100-2112-M-003-001-MY3.
Rheological properties of alumina injection feedstocks
Scientific Electronic Library Online (English)
Vivian Alexandra, Krauss; Eduardo Nunes, Pires; Alo�sio Nelmo, Klein; M�rcio Celso, Fredel.
Full Text Available The rheological behavior of alumina molding feedstocks containing polyethylene glycol (PEG), polyvinylbutyral (PVB) and stearic acid (SA) and having different powder loads were analyzed using a capillary rheometer. Some of the feedstocks showed a pseudoplastic behavior of n [...] e appearance of weld lines on molded parts. Their viscosity also displayed a strong dependence on the shear rate. The slip phenomenon, which can cause an unsteady front flow, was also observed. The results indicate that the feedstock containing a lower powder load displayed the best rheological behavior. The 55 vol. % powder loaded feedstock presented the best rheological behavior, thus appearing to be more suitable than the formulation containing a vol. 59% powder load, which attained viscosities exceeding 10� Pa.s at low shear rates, indicating its unsuitability for injection molding.
Doping electrolyte by charged nanoparticles
Shao, Linbo; Zheng, Mingxin; Wang, Wei
Ions in electrolytes have been proposed to resemble carriers in solid semiconductors over decades. Recently, nanofluidic devices have been demonstrated to phenomenologically mimic semiconductor devices by modulating ion concentrations near the interface of electrolytes and solids. However, the link between the ion transportation in nanofluidics and the solid semiconductor is still missing. This letter proposes an electrolyte doping scheme by introducing charged nanoparticles as dopers, which holds potential in modulating ion concentration in a bulk sense. These nanoparticles show a strong modulation of ion concentrations, and thus bridge the ion transportation in nanofluidics with the well-established semiconductor physics. Ionic diodes based on the present electrolyte doping picture are theoretically and experimentally demonstrated. The current-voltage characteristics are scrutinized by the depletion approximation.
Electrolyte salts for power sources
Energy Technology Data Exchange (ETDEWEB)
Doddapaneni, Narayan (10516 Royal Birkdale, NE., Albuquerque, NM 87111); Ingersoll, David (5824 Mimosa Pl., NE., Albuquerque, NM 87111)
Electrolyte salts for power sources comprising salts of phenyl polysulfonic acids and phenyl polyphosphonic acids. The preferred salts are alkali and alkaline earth metal salts, most preferably lithium salts.
Electrolyte salts for power sources
Energy Technology Data Exchange (ETDEWEB)
Doddapaneni, N.; Ingersoll, D.
Electrolyte salts are disclosed for power sources comprising salts of phenyl polysulfonic acids and phenyl polyphosphonic acids. The preferred salts are alkali and alkaline earth metal salts, most preferably lithium salts. 2 figs.
Composite solid polymer electrolyte membranes
Formato, Richard M.; Kovar, Robert F.; Osenar, Paul; Landrau, Nelson; Rubin, Leslie S.
The present invention relates to composite solid polymer electrolyte membranes (SPEMs) which include a porous polymer substrate interpenetrated with an ion-conducting material. SPEMs of the present invention are useful in electrochemical applications, including fuel cells and electrodialysis.
Electrolytes for lithium ion batteries
Vaughey, John; Jansen, Andrew N.; Dees, Dennis W.
A family of electrolytes for use in a lithium ion battery. The genus of electrolytes includes ketone-based solvents, such as, 2,4-dimethyl-3-pentanone; 3,3-dimethyl 2-butanone(pinacolone) and 2-butanone. These solvents can be used in combination with non-Lewis Acid salts, such as Li.sub.2[B.sub.12F.sub.12] and LiBOB.
Rheology of interfacial protein-polysaccharide composites
Fischer, P.
The morphology and mechanical properties of protein adsorption layers can significantly be altered by the presence of surfactants, lipids, particles, other proteins, and polysaccharides. In food emulsions, polysaccharides are primarily considered as bulk thickener but can under appropriate environmental conditions stabilize or destabilize the protein adsorption layer and, thus, the entire emulsion system. Despite their ubiquitous usage as stabilization agent, relatively few investigations focus on the interfacial rheology of composite protein/polysaccharide adsorption layers. The manuscript provides a brief review on both main stabilization mechanisms, thermodynamic phase separation and electrostatic interaction and discusses the rheological response in light of the environmental conditions such as ionic strength and pH.
Rheology of zirconia-alumina gelcasting slurries
International Nuclear Information System (INIS)
This paper reports that the rheology of zirconia-alumina composite slurries for gelcasting was studied in order to maximize the solids loading. The viscosity and yield stress were controlled by adjusting the pH. This approach allows the solids loading to be maximized for the gelcasting of near-net-shape composites. A strong correspondence exists among the rheological behavior, the surface charge on the particles, colloidal stability, and the maximum solids loading. The best pH conditions for gelcasting composites depends on the specific binary compositions
Lithium Polymer Electrolytes and Solid State NMR
Berkeley, Emily R.
Research is being done at the Glenn Research Center (GRC) developing new kinds of batteries that do not depend on a solution. Currently, batteries use liquid electrolytes containing lithium. Problems with the liquid electrolyte are (1) solvents used can leak out of the battery, so larger, more restrictive, packages have to be made, inhibiting the diversity of application and decreasing the power density; (2) the liquid is incompatible with the lithium metal anode, so alternative, less efficient, anodes are required. The Materials Department at GRC has been working to synthesize polymer electrolytes that can replace the liquid electrolytes. The advantages are that polymer electrolytes do not have the potential to leak so they can be used for a variety of tasks, small or large, including in the space rover or in space suits. The polymers generated by Dr. Mary Ann Meador's group are in the form of rod -coil structures. The rod aspect gives the polymer structural integrity, while the coil makes it flexible. Lithium ions are used in these polymers because of their high mobility. The coils have repeating units of oxygen which stabilize the positive lithium by donating electron density. This aids in the movement of the lithium within the polymer, which contributes to higher conductivity. In addition to conductivity testing, these polymers are characterized using DSC, TGA, FTIR, and solid state NMR. Solid state NMR is used in classifying materials that are not soluble in solvents, such as polymers. The NMR spins the sample at a magic angle (54.7') allowing the significant peaks to emerge. Although solid state NMR is a helpful technique in determining bonding, the process of preparing the sample and tuning it properly are intricate jobs that require patience; especially since each run takes about six hours. The NMR allows for the advancement of polymer synthesis by showing if the expected results were achieved. Using the NMR, in addition to looking at polymers, allows for participation on a variety of other projects, including aero-gels and carbon graphite mat en als. The goals of the polymer electrolyte research are to improve the physical properties of the polymers. This includes improving conductivity, durability, and expanding the temperature range over which it is effective. Currently, good conductivity is only present at high temperatures. My goals are to experiment with different arrangements of rods and coils to achieve these desirable properties. Some of my experiments include changing the number of repeat units in the polymer, the size of the diamines, and the types of coil. Analysis of these new polymers indicates improvement in some properties, such as lower glass transition temperature; however, they are not as flexible as desired. With further research we hope to produce polymers that encompass all of these properties to a high degree.
Preparation of poly(acrylonitrile-butyl acrylate) gel electrolyte for lithium-ion batteries
International Nuclear Information System (INIS)
Poly(acrylonitrile-butyl acrylate) gel polymer electrolyte was prepared for lithium ion batteries. The preparation started with synthesis of poly(acrylonitrile-butyl acrylate) by radical emulsion polymerization, followed by phase inversion to produce microporous membrane. Then, the microporous gel polymer electrolytes (MGPEs) was prepared with the microporous membrane and LiPF6 in ethylene carbonate/diethyl carbonate. The dry microporous membrane showed a fracture strength as high as 18.98 MPa. As-prepared gel polymer electrolytes presented ionic conductivity in excess of 3.0 x 10-3 S cm-1 at ambient temperature and a decomposition voltage over 6.6 V. The results showed that the as-prepared gel polymer electrolytes were promising materials for Li-ion batteries
Influence of the type of electrolyte on the morphological and crystallographic characteristics of lead powder particles
Directory of Open Access Journals (Sweden)
Nikoli? Neboj�a D.
Full Text Available Lead electrodeposition processes from the basic (nitrate and complex (acetate electrolytes were mutually compared by the scanning electron microscopic and the X-ray diffraction analysis of the produced powder particles. The shape of dendritic particles strongly depended on the type of electrolyte. The dendrites composed of stalk and weakly developed primary branches (the primary type were predominantly formed from the basic electrolyte. The ramified dendrites composed of stalk and of both primary and secondary branches (the secondary type were mainly formed from the complex electrolyte. In the both type of powder particles Pb crystallites were predominantly oriented in the (111 plane. Formation of powder particles of the different shape with the strong (111 preferred orientation was discussed and explained by the consideration of the general characteristics of the growth of a crystal in the electrocrystallization processes. [Projekat Ministarstva nauke Republike Srbije, br. 172046: Electrochemical synthesis and characterization of nanostructured functional materials for application in new technologies
Lithium-ion conducting electrolyte salts for lithium batteries.
Aravindan, Vanchiappan; Gnanaraj, Joe; Madhavi, Srinivasan; Liu, Hua-Kun
This paper presents an overview of the various types of lithium salts used to conduct Li(+) ions in electrolyte solutions for lithium rechargeable batteries. More emphasis is paid towards lithium salts and their ionic conductivity in conventional solutions, solid-electrolyte interface (SEI) formation towards carbonaceous anodes and the effect of anions on the aluminium current collector. The physicochemical and functional parameters relevant to electrochemical properties, that is, electrochemical stabilities, are also presented. The new types of lithium salts, such as the bis(oxalato)borate (LiBOB), oxalyldifluoroborate (LiODFB) and fluoroalkylphosphate (LiFAP), are described in detail with their appropriate synthesis procedures, possible decomposition mechanism for SEI formation and prospect of using them in future generation lithium-ion batteries. Finally, the state-of-the-art of the system is given and some interesting strategies for the future developments are illustrated. PMID:22114046
Directory of Open Access Journals (Sweden)
Aurelia Ionescu
Full Text Available Chickpea proteins are used as ingredients in comminuted sausage products and many oriental textured foods. Rheological behaviour of chickpea protein concentrate was studied using a controlled stress rheometer. The protein dispersion prepared with phosphate buffer at pH 7.0 presented non-Newtonian shear thinning behaviour and rheological data well fitted to the Sisko, Carreau and Cross models. The viscoelastic properties of the chickpea protein suspensions were estimated by measuring the storage and loss moduli in oscillatory frequency conditions (0.1-10 Hz at 20�C. Moreover, thermally induced gelation of the chickpea proteins (16, 24 and 36% was studied at pH 7.0 and 4.5 in the temperature range 50 to 100oC and salt concentration ranging from 0 to 1 M. Gelling behaviour was quantified by means of dynamic rheological measurements. Gels formation was preceded by the decrease of storage modulus and loss moduli, coupled with the increase of the phase angle (delta. The beginning of thermal gelation was influenced by protein concentration, pH and salt level. In all studied cases, storage modulus increased rapidly in the temperature range 70-90�C. All rheological parameters measured at 90�C were significantly higher at pH 4.5 compared to pH 7.0.
Aggregate of nanoparticles: rheological and mechanical properties
Directory of Open Access Journals (Sweden)
Wang Yu
Full Text Available Abstract The understanding of the rheological and mechanical properties of nanoparticle aggregates is important for the application of nanofillers in nanocompoistes. In this work, we report a rheological study on the rheological and mechanical properties of nano-silica agglomerates in the form of gel network mainly constructed by hydrogen bonds. The elastic model for rubber is modified to analyze the elastic behavior of the agglomerates. By this modified elastic model, the size of the network mesh can be estimated by the elastic modulus of the network which can be easily obtained by rheology. The stress to destroy the aggregates, i.e., the yield stress (?y , and the elastic modulus (G' of the network are found to be depended on the concentration of nano-silica (?, wt.% with the power of 4.02 and 3.83, respectively. Via this concentration dependent behavior, we can extrapolate two important mechanical parameters for the agglomerates in a dense packing state (? = 1: the shear modulus and the yield stress. Under large deformation (continuous shear flow, the network structure of the aggregates will experience destruction and reconstruction, which gives rise to fluctuations in the viscosity and a shear-thinning behavior.
Rheological and Sensory Properties of Salad Dressings.
Czech Academy of Sciences Publication Activity Database
�tern, Petr; Mor�vkov�, T.; �ediv�, A.; Panovsk�, Z.; Pokorn�, J.
Bratislava : Slovak society of chemical engineering, 2008. s. 189-189. ISBN 978-80-227-2903-1. [International Conference of SSCHE /35./. 26.05.2008-30.05.2008, Tatransk� Matliare] R&D Projects: GA AV ?R IAA2060404 Institutional research plan: CEZ:AV0Z20600510 Keywords : psychorheology * food dressing * rheological analysis * sensory analysis Subject RIV: BK - Fluid Dynamics
Rheological properties of defense waste slurries
International Nuclear Information System (INIS)
The major objective of this two-year project has been to obtain refined and reliable experimental data about the rheological properties of melter feeds. The research has involved both experimental studies and model development. Two experimental facilities have been set up to measure viscosity and pressure drop. Mathematical models have been developed as a result of experimental observation and fundamental rheological theory. The model has the capability to predict the viscosity of melter slurries in a range of experimental conditions. The final results of the investigation could be used to enhance the current design base for slurry transportation systems and improve the performance of the slurry mixing process. If successful, the cost of this waste treatment will be reduced, and disposal safety will be increased. The specific objectives for this project included: (1) the design, implementation, and validation of the experimental facility in both batch and continuous operating modes; (2) the identification and preparation of melter feed samples of both the SRS and Hanford waste slurries at multiple solids concentration levels; (3) the measurement and analysis of the melter feeds to determine the effects of the solids concentration, pH value, and other factors on the rheological properties of the slurries; (4) the correlation of the rheological properties as a function of the measured physical and chemical parameters; and (5) transmission of the experimental data and resulting correlation to the DOE site user to guide melter feed preparation and transport equipment design
Measurement of lower electrolytic domain boundaries of zirconia electrolytes
International Nuclear Information System (INIS)
Zirconia electrolytes have to be operated at low temperatures(?523 K) when used as oxygen sensor in liquid alkali metals. Only at such low temperatures the chemical attack by sodium on the electrolyte is slow and the lower electrolytic domain boundary (LEDB) of zirconia electrolytes is sufficiently low. But the LEDB data for these electrolytes are available only for temperatures above 823. This is due to the limitations of the available techniques for LEDB measurements, as the electrochemical cells employed for this purpose cannot function well. The impedance of the platinum-air electrode and the solid metal/metal oxide electrodes used in these cells becomes too high below 823 K. In this work, these problems have been overcome by selecting the newly discovered low impedance electrodes, such as ruthenia, for use in place of platinum in the air reference side and liquid metal electrodes, such as, chemically deoxidized indium as low oxygen electrode. Cells based on these electrodes made it possible to measure the LEDB of calcia stabilized zirconia(CS Z) and yttria stabilized zirconia(YSZ) down to 473 K for the first time. The LEDB o f CSZ thus measured can be given as: Log[pO2(LEDB)/atm]= 16.514-43937.3(T/K), (473-11 73K). Similar equation for yttria stabilized zirconia is given as: Log[pO2(LEDB)/atm]=6.4949-38886.6(T/K), (460-941K). These data were used for estimating the suitability of thses electrolytes for use as sensor for oxygen in liquid soor use as sensor for oxygen in liquid sodium. It was found that CSZ has a lower LEDB than YSZ despite the higher ionic conductivity of the latter. A correlation between the thermodynamic stability of various oxide electrolytes and their LEDB was worked out based on the present data and other available data. This correlation was used for identifying new electrolytes for use in liquid sodium metal. (author). 11 refs., 4 figs
RELATIONSHIP BETWEEN MORPHOLOGY, RHEOLOGY AND GLUCOAMYLASE PRODUCTION BY Aspergillus awamori IN SUBMERGED CULTURES
C.R.D. Pamboukian; M. C. R. FACCIOTTI; SCHMIDELL W.
The influence of inoculum preparation on Aspergillus awamori morphology, broth rheology and glucoamylase synthesis in submerged cultures was investigated. A series of runs were performed in fermenters, using initial total reducing sugar concentrations of 20 g/L and 80 g/L. The inocula were prepared in a rotary shaker, at 35oC and 200 rev/min, using a spore concentration of 9.2 x 105 spores/mL and varying both cultivation time and medium pH during the spore germination step. Three types of ino...
High elastic modulus polymer electrolytes
Balsara, Nitash Pervez; Singh, Mohit; Eitouni, Hany Basam; Gomez, Enrique Daniel
A polymer that combines high ionic conductivity with the structural properties required for Li electrode stability is useful as a solid phase electrolyte for high energy density, high cycle life batteries that do not suffer from failures due to side reactions and dendrite growth on the Li electrodes, and other potential applications. The polymer electrolyte includes a linear block copolymer having a conductive linear polymer block with a molecular weight of at least 5000 Daltons, a structural linear polymer block with an elastic modulus in excess of 1.times.10.sup.7 Pa and an ionic conductivity of at least 1.times.10.sup.-5 Scm.sup.-1. The electrolyte is made under dry conditions to achieve the noted characteristics.
Towards Prognostics of Electrolytic Capacitors
Celaya, Jose R.; Kulkarni, Chetan; Biswas, Gautam; Goegel, Kai
A remaining useful life prediction algorithm and degradation model for electrolytic capacitors is presented. Electrolytic capacitors are used in several applications ranging from power supplies on critical avionics equipment to power drivers for electro-mechanical actuators. These devices are known for their low reliability and given their criticality in electronics subsystems they are a good candidate for component level prognostics and health management research. Prognostics provides a way to assess remaining useful life of a capacitor based on its current state of health and its anticipated future usage and operational conditions. In particular, experimental results of an accelerated aging test under electrical stresses are presented. The capacitors used in this test form the basis for a remaining life prediction algorithm where a model of the degradation process is suggested. This preliminary remaining life prediction algorithm serves as a demonstration of how prognostics methodologies could be used for electrolytic capacitors.
Anion exchange polymer electrolytes
Kim, Yu Seung; Kim, Dae Sik; Lee, Kwan-Soo
Solid anion exchange polymer electrolytes and compositions comprising chemical compounds comprising a polymeric core, a spacer A, and a guanidine base, wherein said chemical compound is uniformly dispersed in a suitable solvent and has the structure: ##STR00001## wherein: i) A is a spacer having the structure O, S, SO.sub.2, --NH--, --N(CH.sub.2).sub.n, wherein n=1-10, --(CH.sub.2).sub.n--CH.sub.3--, wherein n=1-10, SO.sub.2-Ph, CO-Ph, ##STR00002## wherein R.sub.5, R.sub.6, R.sub.7 and R.sub.8 each are independently --H, --NH.sub.2, F, Cl, Br, CN, or a C.sub.1-C.sub.6 alkyl group, or any combination of thereof; ii) R.sub.9, R.sub.10, R.sub.11, R.sub.12, or R.sub.13 each independently are --H, --CH.sub.3, --NH.sub.2, --NO, --CH.sub.nCH.sub.3 where n=1-6, HC.dbd.O--, NH.sub.2C.dbd.O--, --CH.sub.nCOOH where n=1-6, --(CH.sub.2).sub.n--C(NH.sub.2)--COOH where n=1-6, --CH--(COOH)--CH.sub.2--COOH, --CH.sub.2--CH(O--CH.sub.2CH.sub.3).sub.2, --(C.dbd.S)--NH.sub.2, --(C.dbd.NH)--N--(CH.sub.2).sub.nCH.sub.3, where n=0-6, --NH--(C.dbd.S)--SH, --CH.sub.2--(C.dbd.O)--O--C(CH.sub.3).sub.3, --O--(CH.sub.2).sub.n--CH--(NH.sub.2)--COOH, where n=1-6, --(CH.sub.2).sub.n--CH.dbd.CH wherein n=1-6, --(CH.sub.2).sub.n--CH--CN wherein n=1-6, an aromatic group such as a phenyl, benzyl, phenoxy, methylbenzyl, nitrogen-substituted benzyl or phenyl groups, a halide, or halide-substituted methyl groups; and iii) wherein the composition is suitable for use in a membrane electrode assembly.
The effect of low-molecular-weight poly(ethylene glycol) (PEG) plasticizers on the transport properties of lithium fluorosulfonimide ionic melt electrolytes.
Geiculescu, Olt E; Hallac, Boutros B; Rajagopal, Rama V; Creager, Stephen E; DesMarteau, Darryl D; Borodin, Oleg; Smith, Grant D
The influence of low-molecular-weight poly(ethylene glycol) (PEG, Mw ? 550 Da) plasticizers on the rheology and ion-transport properties of fluorosulfonimide-based polyether ionic melt (IM) electrolytes has been investigated experimentally and via molecular dynamics (MD) simulations. Addition of PEG plasticizer to samples of IM electrolytes caused a decrease in electrolyte viscosity coupled to an increase in ionic conductivity. MD simulations revealed that addition of plasticizer increased self-diffusion coefficients for both cations and anions with the plasticizer being the fastest diffusing species. Application of a VTF model to fit variable-temperature conductivity and fluidity data shows that plasticization decreases the apparent activation energy (Ea) and pre-exponential factor A for ion transport and also for viscous flow. Increased ionic conductivity with plasticization is thought to reflect a combination of factors including lower viscosity and faster polyether chain segmental dynamics in the electrolyte, coupled with a change in the ion transport mechanism to favor ion solvation and transport by polyethers derived from the plasticizer. Current interrupt experiments with Li/electrolyte/Li cells revealed evidence for salt concentration polarization in electrolytes containing large amounts of plasticizer but not in electrolytes without added plasticizer. PMID:24773589
Cyclic Macromolecules: Dynamics and Nonlinear Rheology, Final Report DOE Award # DE-FG02-05ER46218, Texas Tech University
Energy Technology Data Exchange (ETDEWEB)
McKenna, Gregory B.; Grubbs, Robert H.; Kornfield, Julia A.
The work described in the present report had the original goal to produce large, entangled, ring polymers that were uncontaminated by linear chains and to characterize by rheological methods the dynamics of these rings. While the work fell short of this specific goal, the outcomes of the research performed under support from this grant provided novel macromolecular synthesis methods, new separation methods for ring and linear chains, and novel rheological data on bottle brush polymers, wedge polymers and dendron-based ring molecules. The grant funded a total of 8 archival manuscripts and one patent, all of which are attached to the present report.
Electrolytic indium refining from cadmium in glycerine electrolyte
International Nuclear Information System (INIS)
The results of investigations directed on development of electrochemical indium cleaning from cadmium in glycerine base electrolyte are presented. Optimal operational conditions, specific consumption of reactants and electric power are determined. Relationship between variation of concentration of cadmium impurity in refined metal and duration of electrolysis is revealed. The method for determination of cleaning time is proposed. Developed process was put into commercial operation
Improved stability of quasi-solid-state dye-sensitized solar cell based on poly (ethylene oxide)-poly (vinylidene fluoride) polymer-blend electrolytes
Energy Technology Data Exchange (ETDEWEB)
Yang, Ying; Zhou, Cong-hua; Xu, Sheng; Hu, Hao; Chen, Bo-lei; Zhang, Jing; Wu, Su-juan; Liu, Wei [Department of Physics, Wuhan University, Wuhan 430072 (China); Zhao, Xing-zhong [Department of Physics, Wuhan University, Wuhan 430072 (China); Key Laboratory of Acoustic and Photonic Materials and Devices of Ministry of Education, Wuhan University, Wuhan 430072 (China)
We report two improved stability dye-sensitized TiO{sub 2} solar cells using poly (ethylene oxide)-poly (vinylidene fluoride) (PEO-PVDF) polymer-blend electrolytes modified with water and ethanol as hydroxyl-rich small-molecule additives. The effect of additive on the thermal property, viscosity, conductivity and the corresponding performance of the dye-sensitized solar cell (DSSC) were studied. After introducing the water and ethanol into the PEO-PVDF polymer-blend electrolytes, the conductivity is improved compared to that of the un-added electrolyte. This is due to the enhanced free ion concentration and ion transport channels in the electrolyte because of the cross-linking ability of these hydroxyl-rich additives. The increased ion concentration can be proved by the enhanced concentration of I{sup -} and I{sub 3}{sup -} in the additive-modified electrolytes from UV-vis studies. The increased cross-linking network can be explained by the increased glass transition temperature (T{sub g}) and viscosity of these additive-modified electrolytes from DSC and rheology studies. A more homogeneous morphology of ethanol-modified electrolyte from SEM study is used to further explain the better conductivity and stability of the cells based on these additive-modified electrolytes. From the evaluation of additive effect on the performance of the corresponding DSSC, we find that introducing water and ethanol leads to an increase in short-circuit photocurrent density (J{sub sc}). This is due to the efficient transport of I{sup -}/I{sup 3-} caused by enhanced I{sup -}/I{sup 3-} concentration and increased ion transport channels in the electrolyte by adding additives. The best efficiency of 3.9% is achieved in the cell with ethanol-modified electrolyte. (author)
Novel poly(ethylene glycol) gel electrolytes prepared using self-assembled 1,3:2,4-dibenzylidene-D-sorbitol.
Lai, Wei-Chi; Chen, Chien-Chu
Gel electrolytes have usually been prepared by adding gelators or polymers to the liquid organic solvent-based electrolytes. In this study, we proposed a method to prepare gel electrolytes using gelators in liquid (low molecular weight) polymer-based electrolytes. Inexpensive 1,3:2,4-dibenzylidene-D-sorbitol (DBS) was chosen as a gelator for poly(ethylene glycol) (PEG)-based electrolytes at relatively low DBS concentrations. A series of gel electrolytes was produced by varying the DBS amounts, PEG molecular weights and PEG end groups. First, we found that DBS molecules self-assembled into 3-D networks consisting of nanofibrils that were approximately 10 nm in diameter, as measured by transmission electron microscopy; they exhibited spherulite-like morphologies under polarizing optical microscopy. Second, the dynamic rheological measurements demonstrated that the elastic modulus and the dissolution temperature of DBS-PEG gels increased with the increasing DBS content. The thermal degradation temperature of these gels also increased when the DBS concentration increased, as determined by thermogravimetric analysis. In addition, adding DBS may help to facilitate the dissolution of iodide and iodine in PEG due to its ether groups. Furthermore, the conductivity of the prepared DBS-PEG gel electrolytes was similar to that of the liquid PEG electrolytes (without DBS). When used in dye-sensitized solar cells (DSSC), the PEG-based electrolytes having inactive methyl end groups achieved the highest energy conversion efficiency among the tested cells. The efficiency of DSSC filled with our gel electrolytes remained basically the same over a one-month period, implying that the materials were relatively stable. PMID:24651903
A novel MOCVD strategy for the fabrication of cathode in a solid oxide fuel cell: Synthesis of La0.8Sr0.2MnO3 films on YSZ electrolyte pellets
International Nuclear Information System (INIS)
Porous La0.8Sr0.2MnO3 (LSMO) films have been prepared by metal organic chemical vapor deposition (MOCVD) technique for solid oxide fuel cell (SOFC) applications. LSMO samples have been deposited on yttria-stabilized zirconia (YSZ) electrolyte pellets. The adopted in situ strategy involves a molten mixture consisting of the La(hfa)3.diglyme, Sr(hfa)2.tetraglyme, and Mn(tmhd)3 [Hhfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; diglyme = bis(2-methoxyethyl)ether; tetraglyme = 2,5,8,11,14-pentaoxapentadecane; Htmhd = 2,2,6,6-tetramethyl-3,5-heptandione] precursors. It has been shown that porous LSMO films can be obtained through an accurate tuning of processing parameters, which affect the nucleation and growth processes. The structural and compositional characterizations of these films, carried out by X-ray diffraction (XRD) and energy dispersive X-ray analysis, point to the formation of a single polycrystalline La0.8Sr0.2MnO3 phase. The field emission scanning electron microscopy (FE-SEM) images confirm the formation of porous films. To evaluate the electrochemical activity of the cathodic films, an investigation by impedance spectroscopy (IS) has been performed.
A novel MOCVD strategy for the fabrication of cathode in a solid oxide fuel cell: Synthesis of La{sub 0.8}Sr{sub 0.2}MnO{sub 3} films on YSZ electrolyte pellets
Energy Technology Data Exchange (ETDEWEB)
Toro, Roberta G., E-mail: firstname.lastname@example.com [Dipartimento di Scienze Chimiche, Universita di Catania, ISMN-CNR and INSTM, UdR V.le Andrea Doria 6, I-95125 Catania (Italy); Fiorito, Davide M.R.; Fragala, Maria E. [Dipartimento di Scienze Chimiche, Universita di Catania, ISMN-CNR and INSTM, UdR V.le Andrea Doria 6, I-95125 Catania (Italy); Barbucci, Antonio; Carpanese, Maria P. [Dipartimento di Ingegneria Chimica e di Processo, Universita di Genova, and INSTM, UdR P.le Kennedy 1, I-16129 Genova (Italy); Malandrino, Graziella, E-mail: email@example.com [Dipartimento di Scienze Chimiche, Universita di Catania, ISMN-CNR and INSTM, UdR V.le Andrea Doria 6, I-95125 Catania (Italy)
Porous La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSMO) films have been prepared by metal organic chemical vapor deposition (MOCVD) technique for solid oxide fuel cell (SOFC) applications. LSMO samples have been deposited on yttria-stabilized zirconia (YSZ) electrolyte pellets. The adopted in situ strategy involves a molten mixture consisting of the La(hfa){sub 3}.diglyme, Sr(hfa){sub 2}.tetraglyme, and Mn(tmhd){sub 3} [Hhfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; diglyme = bis(2-methoxyethyl)ether; tetraglyme = 2,5,8,11,14-pentaoxapentadecane; Htmhd = 2,2,6,6-tetramethyl-3,5-heptandione] precursors. It has been shown that porous LSMO films can be obtained through an accurate tuning of processing parameters, which affect the nucleation and growth processes. The structural and compositional characterizations of these films, carried out by X-ray diffraction (XRD) and energy dispersive X-ray analysis, point to the formation of a single polycrystalline La{sub 0.8}Sr{sub 0.2}MnO{sub 3} phase. The field emission scanning electron microscopy (FE-SEM) images confirm the formation of porous films. To evaluate the electrochemical activity of the cathodic films, an investigation by impedance spectroscopy (IS) has been performed.
Experimental droplet dynamics and interfacial rheology characterization
Erk, Kendra; Martin, Jeffrey; Schwalbe, Jonathan; Phelan, Frederick, Jr.; Hudson, Steven
Many properties of emulsions arise from interfacial rheology. Recently, a theory of droplet dynamics accounting for interfacial rheology, Marangoni forces and mass transport was developed. Here, we describe experimental observations of droplet dynamics in light of this theory. Using particle tracking velocimetry, we examine the dynamics of surfactant-stabilized droplets in the Poiseuille flow of a microfluidic device. Interfacial shear and dilatational properties are evaluated, and we distinguish viscous and elastic effects. We find that the shear viscosity of the interface populated by block copolymer surfactant is greater than with small molecule alcohol surfactant. Investigation of small droplets is of interest not only for their relevance to emulsion applications, but their small size has potential for improved force sensitivity and temporal resolution. Other droplet dynamic approaches will be discussed.
Colony Rheology: Active Arthropods Generate Flows
Daniels, Karen; Mann, Michael; Charbonneau, Patrick
Hydrodynamic-like flows are observed in biological systems as varied as bacteria, insects, birds, fish, and mammals. Both the phenomenology (e.g. front instabilities, milling motions) and the interaction types (hydrodynamic, direct contact, psychological, excluded-volume) strongly vary between systems, but a question common to all of them is to understand the role of particle-scale fluctuations in controlling large-scale rheological behaviors. We will address these questions through experiments on a new system, Tyrolichus casei (cheese mites), which live in dense, self-mixing colonies composed of a mixture of living mites and inert flour/detritus. In experiments performed in a Hele-Shaw geometry, we observe that the rheology of a colony is strongly dependent on the relative concentration of active and inactive particles. In addition to spreading flows, we also observe that the system can generate convective circulation and auto-compaction.
Shear thickening, frictionless and frictional rheologies
Mari, Romain; Morris, Jeffrey F; Denn, Morton M
Particles suspended in a Newtonian fluid raise the viscosity and also generally give rise to a shear-rate dependent rheology. In particular, pronounced shear thickening is observed at large solid volume fractions. In a recent article (R. Seto, R. Mari, J. F. Morris, and M. M. Denn., Phys. Rev. Lett., 111:218301, 2013) we have considered the minimum set of components to reproduce the experimentally observed shear thickening behavior, including Discontinuous Shear Thickening (DST). We have found frictional contact forces to be essential, and were able to reproduce the experimental behavior by a simulation including this physical ingredient. In the present article, we thoroughly investigate the effect of friction and express it in the framework of the jamming transition. The viscosity divergence at the jamming transition has been a well known phenomenon in suspension rheology, as reflected in many empirical laws for the viscosity. Friction can affect this divergence, and in particular the jamming packing fractio...
The blood rheology in renal pathology.
de Cindio, Bruno; Gabriele, Domenico; Catapano, Gerardo; Fata, Paola; Hackel, Rene; Bonofiglio, Renzo
The blood is a viscoelastic material often studied as a Newtonian or non-linear liquid. Some pathologies and extracorporeal blood treatment processes may affect both the liquid and solid blood component. An adequate rheological technique, able to detect these alterations, may provide clinicians with an important diagnostic aid. Creep tests consisting in the application of a constant stress are very promising because they may roughly separate the liquid-like (i.e., at long response times) from the solid-like (i.e., at short response times) component of the blood rheological behaviour. In this paper, some preliminary results obtained in creep tests on healthy and uremic individuals are reported showing the potentiality of this technique. PMID:17634664
Rheological properties of a calcium smectite
International Nuclear Information System (INIS)
The rheological and mechanical properties of a Ca-smectite have been investigated by different laboratory tests. By these tests the permeability, the water uptake properties, the swelling properties, the swelling pressure, the stress-strain properties, the strength and the creep properties have been determined. The influence of density, temperature, time and stress level have been considered. Mathematical models of the measured properties and behavior of the clay have been suggested so that calculations involving mechanical and rheological scenarios can be made. The behavior of the clay have been discussed with reference to the microstructure and comparisons between the investigated Ca-smectite and a Na-smectite (Mx-80) have been made. One main conclusion is that the difference between the properties and behavior of Ca-smectite and Na-smectite is small at densities >2.0 t/m3. At densities 3 the difference is increasing with decreasing density. (orig./HP)
News concerning gel polymer electrolytes.
Czech Academy of Sciences Publication Activity Database
Sedla?�kov�, M.; Vondr�k, Ji?�; Macal�k, M.
Brno : University of technology Brno, 2009, s. 46-48. ISBN 978-80-214-3943-6. [International Conference Advanced Batteries, Accumulators and Fuel Cells /10./. Brno (CZ), 30.08.2009-02.10.2009] Institutional research plan: CEZ:AV0Z40320502 Keywords : gel polymer electrolytes Subject RIV: CG - Electrochemistry
Rheology and structure of milk protein gels
van Vliet, T; Lakemond, C.M.M.; Visschers, R.W.
Recent studies on gel formation and rheology of milk gels are reviewed. A distinction is made between gels formed by aggregated casein, gels of `pure` whey proteins and gels in which both casein and whey proteins contribute to their properties. For casein' whey protein mixtures, it has been shown that both the fraction whey protein aggregated with the casein particles and whey protein aggregates dispersed in the continuous phase have a large impact on the structural and mechanical properties ...
Predictability of Complex Modulus Using Rheological Models
Md Yusoff, N. I.; Airey, G. D.; Hainin, M. R.
The objective of this study was to investigate the advantages and disadvantages of several linear visco-elastic rheological models applied to the unmodified and polymer-modified bitumens. It was found that all the models studied can be used to predict the linear visco-elastic of unmodified bitumens, aged and unaged samples reasonably well. In contrary, this condition was not really applicable on polymer-modified bitumens particularly for the unaged samples. The measured and predicted data was...
Rheological analysis of crumb rubber modified binder
Mturi, G.A.J.; O'Connell, J.
In South Africa. the use of crumb rubber modified (CRM) bitumen has increased over the years as increased traftic loads have resulted in higher performance requirements. Empirical binder characterisation of CRM bitumen remains widespread internationally, even though empirical properties cannot predict asphalt mix performance. Advanced rheological characterisation of CRM bitumen using a dynamic shear rheometer (DSR) is a superior alternative once the morphological challenge of the binary binde...
Glass transitions and shear thickening suspension rheology
Holmes, Colin B.; Cates, Michael E.; Fuchs, Matthias; Sollich, Peter
We introduce a class of simple models for shear thickening and/ or `jamming' in colloidal suspensions. These are based on schematic mode coupling theory (MCT) of the glass transition, having a memory term that depends on a density variable, and on both the shear stress and the shear rate. (Tensorial aspects of the rheology, such as normal stresses, are ignored for simplicity.) We calculate steady-state flow curves and correlation functions. Depending on model parameters, we ...
Rheological evaluation of pretreated cladding removal waste
International Nuclear Information System (INIS)
Cladding removal waste (CRW) contains concentrations of transuranic (TRU) elements in the 80 to 350 nCi/g range. This waste will require pretreatment before it can be disposed of as glass or grout at Hanford. The CRW will be pretreated with a rare earth strike and solids removal by centrifugation to segregate the TRU fraction from the non-TRU fraction of the waste. The centrifuge centrate will be neutralized with sodium hydroxide. This neutralized cladding removal waste (NCRW) is expected to be suitable for grouting. The TRU solids removed by centrifugation will be vitrified. The goal of the Rheological Evaluation of Pretreated Cladding Removal Waste Program was to evaluate those rheological and transport properties critical to assuring successful handling of the NCRW and TRU solids streams and to demonstrate transfers in a semi-prototypic pumping environment. This goal was achieved by a combination of laboratory and pilot-scale evaluations. The results obtained during these evaluations were correlated with classical rheological models and scaled-up to predict the performance that is likely to occur in the full-scale system. The Program used simulated NCRW and TRU solid slurries. Rockwell Hanford Operations (Rockwell) provided 150 gallons of simulated CRW and 5 gallons of simulated TRU solid slurry. The simulated CRW was neutralized by Pacific Northwest Laboratory (PNL). The physical and rheological properties of the NCRW and TRU solid slurries were evaluated in the laboratory. The properties displayed by NCRW allowed it to be classified as a pseudoplastic or yield-pseudoplastic non-Newtonian fluid. The TRU solids slurry contained very few solids. This slurry exhibited the properties associated with a pseudoplastic non-Newtonian fluid
Rheological evaluation of pretreated cladding removal waste
Energy Technology Data Exchange (ETDEWEB)
McCarthy, D.; Chan, M.K.C.; Lokken, R.O.
Cladding removal waste (CRW) contains concentrations of transuranic (TRU) elements in the 80 to 350 nCi/g range. This waste will require pretreatment before it can be disposed of as glass or grout at Hanford. The CRW will be pretreated with a rare earth strike and solids removal by centrifugation to segregate the TRU fraction from the non-TRU fraction of the waste. The centrifuge centrate will be neutralized with sodium hydroxide. This neutralized cladding removal waste (NCRW) is expected to be suitable for grouting. The TRU solids removed by centrifugation will be vitrified. The goal of the Rheological Evaluation of Pretreated Cladding Removal Waste Program was to evaluate those rheological and transport properties critical to assuring successful handling of the NCRW and TRU solids streams and to demonstrate transfers in a semi-prototypic pumping environment. This goal was achieved by a combination of laboratory and pilot-scale evaluations. The results obtained during these evaluations were correlated with classical rheological models and scaled-up to predict the performance that is likely to occur in the full-scale system. The Program used simulated NCRW and TRU solid slurries. Rockwell Hanford Operations (Rockwell) provided 150 gallons of simulated CRW and 5 gallons of simulated TRU solid slurry. The simulated CRW was neutralized by Pacific Northwest Laboratory (PNL). The physical and rheological properties of the NCRW and TRU solid slurries were evaluated in the laboratory. The properties displayed by NCRW allowed it to be classified as a pseudoplastic or yield-pseudoplastic non-Newtonian fluid. The TRU solids slurry contained very few solids. This slurry exhibited the properties associated with a pseudoplastic non-Newtonian fluid.
Rheology and Dynamics of Colloidal Superballs
Royer, John; Burton, George; Blair, Daniel; Hudson, Steven
Relatively little is known about the role particle shape plays in the dynamics of colloidal suspensions, particularly at higher packing densities where particle interactions and changes in the microstructure become increasingly important. We examine the role of particle shape by characterizing both the bulk rheology and micro-scale diffusion in a suspension of pseudo-cubic silica superballs. Varying the packing density 0 ?eff defined by the minimal sphere needed to enclose the superballs, which roughy collapses the diffusion results.
Relaxation and Rheology in Dense Athermal Suspensions
Olsson, Peter
We study relaxation and rheology of dense athermal suspensions of frictionless particles close below the jamming density. Our key quantity, the relaxation time---determined from the exponential decay of the energy after the shearing has suddenly been switched off---is argued to be a determining factor behind the algebraic divergence of various quantities as the jamming density is approached from below. We also define and measure the ``dissipation time'', which is obtained di...
Dissipation and Rheology of Sheared Soft-Core Frictionless Disks
Va?gberg, Daniel; Olsson, Peter; Teitel, S.
We use numerical simulations to investigate the effect of different dissipative models on the shearing rheology of massive soft-core frictionless disks in two dimensions. We show that the presence of Newtonian (overdamped) vs Bagnoldian (inertial) rheology is related to the formation of large connected clusters of disks, and that sharp transitions may exist between the two as system parameters vary. In the limit of strongly inelastic collisions, we find that rheological curv...
Relationship between Rheology and Molecular Structure of Innovative Crystalline Elastomers
Ahmad, Naveed
The study of the rheology of polyolefins based on homogenous metallocenic catalyst has been mainly devoted to the understanding of material process ability. When used at a more advanced and sophisticated level, however, rheology is a useful tool to highlight the details of the polymer microstructure, such as the chemical stereo-regularity or the degree of chain branching. Rheology is also used to study the crystallization kinetics of the polymers and it gives more precise analysis than the co...
Structure and rheology of organoclay suspensions
International Nuclear Information System (INIS)
We have characterized a montmorillonite-based organoclay dispersed in three different nonaqueous solvents using a combination of x-ray scattering, small-angle neutron scattering (SANS), and ultrasmall angle neutron scattering (USANS), together with rheological measurements. Consistent with these measurements, we present a structural model for the incompletely dispersed clay as consisting of randomly oriented tactoids made of partially overlapping clay sheets, with transverse dimensions of several microns. Intersheet correlation peaks are visible in x-ray scattering, and quantitatively fit by our model structure factor. SANS and USANS together show a power law of about -3 over a wide range of wave numbers below the intersheet correlation peak. Our model relates this power law to a power law distribution of the number of locally overlapping layers in a tactoid. The rheology data show that both storage and loss moduli, as well as yield stress, scale with a power law in volume fraction of about three. Equating the gel onset composition with the overlap of randomly oriented tactoids and taking into account the large transverse dimensions of the tactoids, we predict the gel point to be at or below 0.006 volume fraction organoclay. This is consistent with the rheology data
Rheological Characterization of Shale � Mud Interactions
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W. O. Emofurieta
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In a bid to identify a best drilling fluid for a problematic oil field in the Niger Delta region, rheological tests were carried out on three mud samples; BW1, BW3 and BW4. The results affirm that the load bearing capacity of XP-07 formulated as BW3 and BW4 in this investigation is excellent and fall within the same range or even better than those of REF Mud with a more than 90% drilling success history in Niger Delta. The rheological changes of XP-07 with increase in temperature and �assimilated� microscopic shale particles are very negligible and smaller than those of REF mud. XP-07 has been strongly recommended for all drilling operations in the problematic field. It has been re-emphasised as part of our recommendations that new guidelines for the close monitoring of drilling fluids supplied by mud companies and those actually used in the field (during drilling be put in place.
Key words: Shale � mud interactions; Rheological characterization; Niger delta
Rheological characterization of dilute acid pretreated softwood.
Wiman, Magnus; Palmqvist, Benny; Tornberg, Eva; Lid�n, Gunnar
Large-scale bioethanol production from lignocellulosic biomass will require high solids loading in the enzymatic hydrolysis step. However, slurries of pretreated lignocelluloses are complex fluids due to the fibrous nature, especially at high concentrations of water insoluble solids (WIS). A prerequisite for dealing with transport issues and for developing efficient full-scale processes is a fundamental understanding of the flow properties of pretreated lignocellulose. A comprehensive rheological characterization of dilute acid pretreated spruce has been carried out in this study, accounting for the effects of WIS concentration, particle size distribution (PSD), and the degree of enzymatic hydrolysis. The rheology of pretreated spruce slurries was found to be strongly dependent on the WIS concentration. The storage modulus (G'(LVR)) and yield stress showed typical power-law dependencies on volume fraction and WIS content. Milling of the pretreated material resulted in significantly higher yield stress and viscosity, likely due to narrower PSD, which suggests that the strength of the network of the coarsest fibers determines the rheology of these materials to a large extent. During enzymatic hydrolysis, yield stress and viscosity decreased dramatically, partly due to decreasing WIS content, but possibly also due to changes in fiber properties such as the chemical composition. PMID:21449021
Shear rheology of molten crumb chocolate.
Taylor, J E; Van Damme, I; Johns, M L; Routh, A F; Wilson, D I
The shear rheology of fresh molten chocolate produced from crumb was studied over 5 decades of shear rate using controlled stress devices. The Carreau model was found to be a more accurate description than the traditional Casson model, especially at shear rates between 0.1 and 1 s(-1). At shear rates around 0.1 s(-1) (shear stress approximately 7 Pa) the material exhibited a transition to a solid regime, similar to the behavior reported by Coussot (2005) for other granular suspensions. The nature of the suspension was explored by investigating the effect of solids concentration (0.20 cocoa butter, and (2) a suspension of sugar of a similar size distribution (volume mean 15 mum) in cocoa butter and emulsifier. The chocolate and synthetic chocolate showed very similar rheological profiles under both steady shear and oscillatory shear. The chocolate and the sugar suspension showed similar Krieger-Dougherty dependency on volume fraction, and a noticeable transition to a stiff state at solids volume fractions above approximately 0.5. Similar behavior has been reported by Citerne and others (2001) for a smooth peanut butter, which had a similar particle size distribution and solids loading to chocolate. The results indicate that the melt rheology of the chocolate is dominated by hydrodynamic interactions, although at high solids volume fractions the emulsifier may contribute to the departure of the apparent viscosity from the predicted trend. PMID:19323742
Ageing and Rheology in Soft Materials
Fielding, S M; Cates, M E
We study theoretically the role of ageing in the rheology of soft materials. We define several generalized rheological response functions suited to ageing samples (in which time translation invariance is lost). These are then used to study ageing effects within a simple scalar model (the "soft glassy rheology" or SGR model) whose constitutive equations relate shear stress to shear strain among a set of elastic elements, with distributed yield thresholds, undergoing activated dynamics governed by a "noise temperature", $x$. (Between yields, each element follows affinely the applied shear.) For $1
Dual-Colored DNA Comb Polymers for Single Molecule Rheology
Mai, Danielle; Marciel, Amanda; Schroeder, Charles
We report the synthesis and characterization of branched biopolymers for single molecule rheology. In our work, we utilize a hybrid enzymatic-synthetic approach to graft ``short'' DNA branches to ``long'' DNA backbones, thereby producing macromolecular DNA comb polymers. The branches and backbones are synthesized via polymerase chain reaction with chemically modified deoxyribonucleotides (dNTPs): ``short'' branches consist of Cy5-labeled dNTPs and a terminal azide group, and ``long'' backbones contain dibenzylcyclooctyne-modified (DBCO) dNTPs. In this way, we utilize strain-promoted, copper-free cycloaddition ``click'' reactions for facile grafting of azide-terminated branches at DBCO sites along backbones. Copper-free click reactions are bio-orthogonal and nearly quantitative when carried out under mild conditions. Moreover, comb polymers can be labeled with an intercalating dye (e.g., YOYO) for dual-color fluorescence imaging. We characterized these materials using gel electrophoresis, HPLC, and optical microscopy, with atomic force microscopy in progress. Overall, DNA combs are suitable for single molecule dynamics, and in this way, our work holds the potential to improve our understanding of topologically complex polymer melts and solutions.
Electrolyte measurement device and measurement procedure
Cooper, Kevin R. (Southern Pines, NC); Scribner, Louie L. (Southern Pines, NC)
A method and apparatus for measuring the through-thickness resistance or conductance of a thin electrolyte is provided. The method and apparatus includes positioning a first source electrode on a first side of an electrolyte to be tested, positioning a second source electrode on a second side of the electrolyte, positioning a first sense electrode on the second side of the electrolyte, and positioning a second sense electrode on the first side of the electrolyte. current is then passed between the first and second source electrodes and the voltage between the first and second sense electrodes is measured.
Aliovalently-Doped Garnets for Li Battery Solid State Electrolytes
Schwanz, Derek K.; Marinero, Ernesto E.
We report on a new family of fast ionic conductivity electrolytes based on the garnet LiLaZrO. Partial substitution of Zr by aliovalent atomic species through solid state solution synthesis results in ionic conductivities 2 orders of magnitude larger than the tetragonal phase of LiLaZrO and comparable to that of its cubic phase. The synthesis temperature is 400C lower than that required for the cubic stabilization of LiLaZrO. Ongoing impovements on microstructure and film density as well as optimization of the garnet stoichiometry are expected to yield ionic conductivities surpassing the highest values reported to-date on cubic doped LiLaZrMO (Ta, Al, W, Nb)
Whole body gamma radiation effects on rheological behaviour (deformability) of rat erythrocytes
International Nuclear Information System (INIS)
This study was designed to determine the effect of whole body gamma irradiation on the rheological behaviour of rat erythrocytes (deformability). Animals were divided into 4 irradiated groups and 4 control groups according to their sacrificing time intervals (1 st, 3 rd, 5 th and 7 th days) post-irradiation with dose (6 Gy). In all animals and at the previous time intervals, red blood cell (RBC) membrane proteins electrophoretic pattern, RBC membrane lipids levels (cholesterol and phospholipids), RBC electrolytes levels (sodium, potassium and calcium), corpuscular osmotic fragility and RBC morphological by scanning electron microscopy were determined. Highly significant increase in membrane cholesterol, RBC sodium, calcium and corpuscular osmotic fragility accompanied by highly significant decrease in membrane phospholipids, RBC potassium and RBC deformability were found. No changes in membrane proteins electrophoretic patterns were detected. Morphologically, there were increase in the incidences of echinocytes and spherocytes development, which were time dependent. According to the previous results, irradiation promotes alterations in RBC shape (echinocytosis), membrane skeletal dysfunction, membrane lipid peroxidation, increase in membrane cholesterol/phospholipid content, changes in membrane electrolyte permeability and decrease then increase in osmotic fragility. These alterations in turn led to decrease in cellular deformability as a result of increased membrane ability as a result of increased membrane rigidity and also due to cells dehydration caused by excess leakage of potassium ions from the RBCs
Review Of Rheology Modifiers For Hanford Waste
International Nuclear Information System (INIS)
As part of Savannah River National Laboratory (SRNL)'s strategic development scope for the Department of Energy - Office of River Protection (DOE-ORP) Hanford Tank Waste Treatment and Immobilization Plant (WTP) waste feed acceptance and product qualification scope, the SRNL has been requested to recommend candidate rheology modifiers to be evaluated to adjust slurry properties in the Hanford Tank Farm. SRNL has performed extensive testing of rheology modifiers for use with Defense Waste Processing Facility (DWPF) simulated melter feed - a high undissolved solids (UDS) mixture of simulated Savannah River Site (SRS) Tank Farm sludge, nitric and formic acids, and glass frit. A much smaller set of evaluations with Hanford simulated waste have also been completed. This report summarizes past work and recommends modifiers for further evaluation with Hanford simulated wastes followed by verification with actual waste samples. Based on the review of available data, a few compounds/systems appear to hold the most promise. For all types of evaluated simulated wastes (caustic Handford tank waste and DWPF processing samples with pH ranging from slightly acidic to slightly caustic), polyacrylic acid had positive impacts on rheology. Citric acid also showed improvement in yield stress on a wide variety of samples. It is recommended that both polyacrylic acid and citric acid be further evaluated as rheology modifiers for Hanford waste. These materials are weak organic acids with the following potential issues: The acidic nature of the modifiers may impact waste pH, if added in very large doses. If pH is significantly reduced by the modifier addition, dissolution of UDS and increased corrosion of tanks, piping, pumps, and other process equipment could occur. Smaller shifts in pH could reduce aluminum solubility, which would be expected to increase the yield stress of the sludge. Therefore, it is expected that use of an acidic modifier would be limited to concentrations that do not appreciably change the pH of the waste; Organics are typically reductants and could impact glass REDOX if not accounted for in the reductant addition calculations; Stability of the modifiers in a caustic, radioactive environment is not known, but some of the modifiers tested were specifically designed to withstand caustic conditions; These acids will add to the total organic carbon content of the wastes. Radiolytic decomposition of the acids could result in organic and hydrogen gas generation. These potential impacts must be addressed in future studies with simulants representative of real waste and finally with tests using actual waste based on the rheology differences seen between SRS simulants and actual waste. The only non-organic modifier evaluated was sodium metasilicate. Further evaluation of this modifier is recommended if a reducing modifier is a concern
Composite electrode/electrolyte structure
Visco, Steven J. (Berkeley, CA); Jacobson, Craig P. (El Cerrito, CA); DeJonghe, Lutgard C. (Lafayette, CA)
Provided is an electrode fabricated from highly electronically conductive materials such as metals, metal alloys, or electronically conductive ceramics. The electronic conductivity of the electrode substrate is maximized. Onto this electrode in the green state, a green ionic (e.g., electrolyte) film is deposited and the assembly is co-fired at a temperature suitable to fully densify the film while the substrate retains porosity. Subsequently, a catalytic material is added to the electrode structure by infiltration of a metal salt and subsequent low temperature firing. The invention allows for an electrode with high electronic conductivity and sufficient catalytic activity to achieve high power density in ionic (electrochemical) devices such as fuel cells and electrolytic gas separation systems.
Electrolytic precipitation of ammonium diuranate
International Nuclear Information System (INIS)
Continuous precipitation of ammonium diuranate from a solution of uranyl sulphate and ammonium sulphate in the cathode compartment of an electrolytic cell has been investigated. It is found that the rate of precipitation and the settling rate of the precipitate can be correlated with the current consumed per unit volume of catholyte solution. The weight fraction of uranium in the dried solid product appears to be constant over the range of operating conditions used
Plasma electrolytic oxidation of metals
Stojadinovi? Stevan
In this lecture results of the investigation of plasma electrolytic oxidation (PEO) process on some metals (aluminum, titanium, tantalum, magnesium, and zirconium) were presented. Whole process involves anodizing metals above the dielectric breakdown voltage where numerous micro-discharges are generated continuously over the coating surface. For the characterization of PEO process optical emission spectroscopy and real-time imaging were used. These investigations enabled the determinati...
Modeling elongational and shear rheology of two LDPE melts.
Czech Academy of Sciences Publication Activity Database
Rol�n-Garrido, V. H.; Wagner, M. H.; Pivokonsk�, Radek; Filip, Petr; Zatloukal, M.
Cardiff : Cardiff University, 2009. s. 1-1. [Annual European Rheology Conference /5./. 15.04.2009-17.04.2009, Cardiff] R&D Projects: GA AV ?R IAA200600703 Institutional research plan: CEZ:AV0Z20600510 Keywords : Rheology * MSF model * shear flow * elongational flow * strain hardening * low-density polyethylene * polymer melts Subject RIV: BK - Fluid Dynamics
Rheological behaviour of metallocene polypropylenes prepared by reactive extrusion process.
Czech Academy of Sciences Publication Activity Database
Pivokonsk�, Radek; Filip, Petr; Zatloukal, M.; Tzoganakis, C.
Lisbon : European Society of Rheology, 2012. s. 394. [International Congress on Rheology /16./. 05.08.2012-10.08.2012, Lisbon] R&D Projects: GA ?R GA103/09/2066 Keywords : metallocene polypropylene * constitutive modelling * differential models Subject RIV: BK - Fluid Dynamics
Regional rheological differences in locomoting neutrophils.
Yanai, M; Butler, J P; Suzuki, T; Sasaki, H; Higuchi, H
Intracellular rheology is a useful probe of the mechanisms underlying spontaneous or chemotactic locomotion and transcellular migration of leukocytes. We characterized regional rheological differences between the leading, body, and trailing regions of isolated, adherent, and spontaneously locomoting human neutrophils. We optically trapped intracellular granules and measured their displacement for 500 ms after a 100-nm step change in the trap position. Results were analyzed in terms of simple viscoelasticity and with the use of structural damping (stress relaxation follows a power law in time). Structural damping fit the data better than did viscoelasticity. Regional viscoelastic stiffness and viscosity or structural damping storage and loss moduli were all significantly lower in leading regions than in pooled body and/or trailing regions (the latter were not significantly different). Structural damping showed similar levels of elastic and dissipative stresses in body and/or trailing regions; leading regions were significantly more fluidlike (increased power law exponent). Cytoskeletal disruption with cytochalasin D or nocodazole made body and/or trailing regions approximately 50% less elastic and less viscous. Cytochalasin D completely suppressed pseudopodial formation and locomotion; nocodazole had no effect on leading regions. Neither drug changed the dissipation-storage energy ratio. These results differ from those of studies of neutrophils and other cell types probed at the cell membrane via beta(2)-integrin receptors, which suggests a distinct role for the cell cortex or focal adhesion complexes. We conclude that 1) structural damping well describes intracellular rheology, and 2) while not conclusive, the significantly more fluidlike behavior of the leading edge supports the idea that intracellular pressure may be the origin of motive force in neutrophil locomotion. PMID:15163623
Vertically Integrated Rheology of Deforming Oceanic Lithosphere
Mishra, J. K.; Gordon, R. G.
The tectonics of the oceans have traditionally been modeled in terms of rigid plates interacting at narrow boundaries. The now well-documented existence of diffuse oceanic plate boundaries, across which relative motion is distributed over hundreds to thousands of kilometers, demonstrates the need for a different approach to understanding the tectonics and geodynamics of a substantial fraction of oceanic lithosphere. A model that has usefully been applied to diffuse zones of continental deformation is that of a thin viscous sheet of fluid obeying a power-law rheology. The model has few adjustable parameters, typically a power-law exponent, n, and the Argand number [England & McKenzie, 1982], which is a measure of the size of buoyancy forces caused by the deformation, and which can be neglected for deformation of oceanic lithosphere. In prior investigations of a thin sheet of power-law fluid for continental regions, most studies have found that the most appropriate power-law exponent is ?3 [e.g., England & Molnar 1991, 1997], but a value as large as ?10 has been recently suggested by Dayem et al. [2009]. Because the rheology of oceanic lithosphere differs significantly from that of continental lithosphere, the most appropriate exponent may be larger than 3, and should in some sense be an appropriately weighted average between the properties of the upper lithosphere, which deforms brittlely and semi-brittlely, and for which the power-law exponent is n ? ?, and the lower lithosphere, which deforms by dislocation glide [Goetze 1978; Evans & Goetze 1979; Ratteron et al. 2003; Dayem et al. 2009; Mei et al. 2010], which obeys an exponential law, and by dislocation creep for which n?3 [Sonder & England, 1986]. To estimate the appropriate power-law exponent consistent with laboratory experiments we determine strain rate as a function of applied end load on the lithosphere for various ages of lithosphere. We find that a power-law fluid well approximates the vertically integrated rheology of oceanic lithosphere determined from laboratory experiments and that the best-fitting power-law exponent for the vertically integrated rheology is insensitive to strain rate. We also find that, except for very young lithosphere (< ?10 Ma old), the best-fitting power law exponent is insensitive to the age of the lithosphere, with the value of the exponent being between 14 and 16 when failing for thrust faulting for the flow laws of Kohlstedt et al [1995] and between 15 and 19 for more recently published flow laws. These results support the application of thin viscous sheet models to diffuse oceanic plate boundaries, such as the ones accommodating motion between the India, Capricorn, and Australia plates in the Indian Ocean.
Rheology of Liquid-Solid System.
Czech Academy of Sciences Publication Activity Database
Kulaviak, Luk�; Ve?e?, Marek; R?�i?ka, Marek; Draho�, Ji?�; Hladil, Jind?ich
Praha : ?esk� spole?nost chemick�ho in�en�rstv�, 2007 - (Halfar, R.). s. 46 ISBN 80-86059-47-2. [Konference chemick�ho a procesn�ho in�en�rstv� CHISA 2007 /54./. 15.10.2007-18.10.2007, Srn�, �umava] R&D Projects: GA ?R(CZ) GA104/05/2566; GA ?R GA104/06/1418; GA ?R GA104/07/1110; GA AV ?R IAAX00130702; GA ?R GP104/06/P287 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z3013912 Keywords : suspension * shear stress * rheology Subject RIV: CI - Industrial Chemistry, Chemical Engineering
Directory of Open Access Journals (Sweden)
Full Text Available Rheological behavior of this article presents hydraulic oil. Dynamic viscosity of hydraulic oil was determined at temperatures between 400C -900C and shear rates ranging from 3.3-120s^-1. Temperature of hydraulic oil at 313K has a Bingham fluid behavior with correlation coefficient value close to one. Between 323 and 333K temperature behavior of oil has a Casson fluid and the temperature range 343 to363K oil and behaves like an Ostwald-de Waele fluid.
Rheological and phase behaviour of amphiphilic lipids
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Alfaro, M. C.
Full Text Available This chapter reviews the different association structures which are likely to be formed by amphiphilic lipids in the liquid-crystalline state and their corresponding shear flow properties. The structure and rheological behaviour of thermotropic liquid crystals, emphasizing the properties of smectic mesophases, and those of lyotropic liquid crystals such as: nematic, lamellar, diluted lamellar, lamellar dispersions, hexagonal and cubic mesophases are described. The importance of a comprehensive rheological characterisation, including rheo-optical techniques, is pointed out for their practical applications, development of formulations and as a useful technique to assist in the determination of phase diagrams. A historical approach has been used to discuss the evolving field of the rheology and structure identification of liquid crystals formed by amphiphilic lipids and surfactants. Non-Newtonian viscous shear flow, thixotropic and antithixotropic phenomena, linear viscoelastic properties -described by dynamic and creep compliance experiments- and non-linear viscoelastic properties - described by the difference of normal stresses and stress relaxation tests are interpreted on the basis of a microstructure-rheology relationship. The polycrystalline nature of liquid crystals turns out to be rather sensitive to shear due to the change of both size and orientation of the liquid-crystalline monodomains under flow.En este cap�tulo se realiza una revisi�n de las distintas estructuras coloidales de asociaci�n que pueden formar los l�pidos anfif�licos en estado l�quido-cristalino y de sus correspondientes propiedades de flujo en cizalla. Se describe la estructura y comportamiento reol�gico de cristales l�quidos termotr�picos, con �nfasis en los de tipo esm�ctico, fases gel, y cristales l�quidos liotr�picos: nem�ticos, laminares, laminares diluidos, dispersiones de laminares, hexagonales y c�bicos. Se hace hincapi� en la importancia de una buena caracterizaci�n reol�gica y reo-�ptica de cara a sus aplicaciones pr�cticas, desarrollo de formulaciones y como una t�cnica �til para determinar diagramas de fases y detectar cambios de estructura. Se ha usado una metodolog�a hist�rica para analizar la evoluci�n de la caracterizaci�n reol�gica e identificaci�n de las diferentes estructuras l�quido-cristalinas y estructuras afines. La interpretaci�n de comportamientos de flujo viscoso no newtonianos, fen�menos tixotr�picos y antitixotr�picos y de las propiedades viscoel�sticas lineales, determinadas con ensayos din�micos y de fluencia, y no lineales, descritas mediante la diferencia de esfuerzos normales y ensayos de relajaci�n del esfuerzo, se basa en la interrelaci�n microestructuracomportamiento reol�gico. La naturaleza policristalina de los cristales l�quidos resulta ser muy sensible a la cizalla, debido al cambio de tama�o y orientaci�n de los dominios l�quidocristalinos mientras fluyen.
Rheological Characterization of Shale � Mud Interactions
Emofurieta, W. O.; Odeh, A. O.
In a bid to identify a best drilling fluid for a problematic oil field in the Niger Delta region, rheological tests were carried out on three mud samples; BW1, BW3 and BW4. The results affirm that the load bearing capacity of XP-07 formulated as BW3 and BW4 in this investigation is excellent and fall within the same range or even better than those of REF Mud with a more ...
Rheology of spinel sludge in molten glass
International Nuclear Information System (INIS)
Spinel sludge, which forms while vitrifying high-level waste, obstructs the flow of molten glass and damages the melter. The effectiveness of removing spinel sludge from a high-level waste glass melter depends on its rheological behavior. We prepared spinel sludge in a laboratory crucible by allowing spinel to settle from molten glass and measured the response of the sludge to shear using a rotating spindle viscometer. The shear stress increased nonlinearly with the velocity gradient (the shear rate) and with time at a constant velocity gradient, as is typical for a pseudoplastic rheopectic liquid. The apparent viscosity of the sludge substantially increased when RuO-2 needles were present
Melt rheology and its applications in the plastics industry
Dealy, John M
This is the second edition of Melt Rheology and its Role in Plastics Processing, although the title has changed to reflect its broadened scope. Advances in the recent years in rheometer technology and polymer science have greatly enhanced the usefulness of rheology in the plastics industry. It is now possible to design polymers having specific molecular structures and to predict the flow properties of melts having those structures. In addition, rheological properties now provide more precise information about molecular structure. This book provides all the information that is needed for the intelligent application of rheology in the development of new polymers, the determination of molecular structure and the correlation of processability with laboratory test data. Theory and equations are limited to what is essential for the use of rheology in the characterization of polymers, the development of new plastics materials and the prediction of plastics processing behavior. The emphasis is on information that wil...
Rheological model and flow equation for elasto-viscoplastic mixtures ????????????? ?????? ? ????????? ??????? ??????-?????-?????????? ?????
Directory of Open Access Journals (Sweden)
Luk�yanov Nikolai Andreevich
Full Text Available Advanced building materials technologies widely employ polymers. Viscoelastic and viscoplastic mixtures are used in the manufacturing of building materials and finishing products. Rheology studies deformation and flow patterns of different bodies.Markus Reiner developed mathematical formulations for rheological flows of viscous and plastic materials, processes of deformation of different bodies, behaviour of materials exposed to strain loads.A rheological flow of any material depends on deformation. Integrated analysis of linear deformations and strain is used to identify a relative change in the volume of an elasto-viscoplastic body. The flow of materials depends on their physicochemical properties. The flow of an elastic-viscous-plastic mixture in channels demonstrates its viscoelastic properties. Rheological equation of Oldroyd is used to relate strain to speed of displacement and the time of relaxation. The flow of polymeric materials is examined using Bingham�s rheological model.?????????? ??????? ????????? ?????????? ??????-?????-??????????? ?????????. ?????????? ???????????????? ????????? ???????? ? ????????????? ? ?????? ??????? ??????????, ??????? ?????????? ???????? ??????????? ????????? ????. ???????? ??????????? ??? ??????????? ?????????????? ????????? ?????? ??????-?????-????????????? ???? ??? ???????? ??????????. ?????????? ??????????? ?????????? ???????? ?????????????? ???????? ???? ?? ??????? ?????????? ??????????. ????????? ??????-?????-?????????? ????? ??????????? ?? ??????? ????????????? ?????? ???? ???????.
Nanocomposite polymer electrolyte for rechargeable magnesium batteries
Energy Technology Data Exchange (ETDEWEB)
Shao, Yuyan; Rajput, Nav Nidhi; Hu, Jian Z.; Hu, Mary Y.; Liu, Tianbiao L.; Wei, Zhehao; Gu, Meng; Deng, Xuchu; Xu, Suochang; Han, Kee Sung; Wang, Jiulin; Nie, Zimin; Li, Guosheng; Zavadil, K.; Xiao, Jie; Wang, Chong M.; Henderson, Wesley A.; Zhang, Jiguang; Wang, Yong; Mueller, Karl T.; Persson, Kristin A.; Liu, Jun
Nanocomposite polymer electrolytes present new opportunities for rechargeable magnesium batteries. However, few polymer electrolytes have demonstrated reversible Mg deposition/dissolution and those that have still contain volatile liquids such as tetrahydrofuran (THF). In this work, we report a nanocomposite polymer electrolyte based on poly(ethylene oxide) (PEO), Mg(BH4)2 and MgO nanoparticles for rechargeable Mg batteries. Cells with this electrolyte have a high coulombic efficiency of 98% for Mg plating/stripping and a high cycling stability. Through combined experiment-modeling investigations, a correlation between improved solvation of the salt and solvent chain length, chelation and oxygen denticity is established. Following the same trend, the nanocomposite polymer electrolyte is inferred to enhance the dissociation of the salt Mg(BH4)2 and thus improve the electrochemical performance. The insights and design metrics thus obtained may be used in nanocomposite electrolytes for other multivalent systems.
Solution rheology of polyelectrolytes and polyelectrolyte-surfactant systems
Plucktaveesak, Nopparat
The fundamental understanding of polyelectrolytes in aqueous solutions is an important branch of polymer research. In this work, the rheological properties of polyelectrolytes and polyelectrolyte/surfactant systems are studied. Various synthetic poly electrolytes are chosen with varied hydrophobicity. We discuss the effects of adding various surfactants to aqueous solutions of poly(ethylene oxide)-b-poly(propylene oxide)- b-polyethylene oxide)-g-poly(acrylic acid) (PEO-PPO-PAA) in the first chapter. Thermogelation in aqueous solutions of PEO-PPO-PAA is due to micellization caused by aggregation of poly(propylene oxide) (PPO) blocks resulting from temperature-induced dehydration of PPO. When nonionic surfactants with hydrophilic-lipophilic balance (HLB) parameter exceeding 11 or Cn alkylsulfates; n-octyl (C8), n-decyl (C 10) and n-dodecyl (C12) sulfates are added, the gelation threshold temperature (Tgel) of 1.0wt% PEO-PPO-PAA in aqueous solutions increases. In contrast, when nonionic surfactants with HLB below 11 are added, the gelation temperature decreases. On the other hand, alkylsulfates with n = 16 or 18 and poly(ethylene oxide) (PEO) do not affect the Tgel. The results imply that both hydrophobicity and tail length of the added surfactant play important roles in the interaction of PEO-PPO-PAA micelles and the surfactant. In the second chapter, the solution behavior of alternating copolymers of maleic acid and hydrophobic monomer is studied. The alternating structure of monomers with two-carboxylic groups and hydrophobic monomers make these copolymers unique. Under appropriate conditions, these carboxylic groups dissociate leaving charges on the chain. The potentiometric titrations of copolymer solutions with added CaCl2 reveal two distinct dissociation processes corresponding to the dissociation of the two adjacent carboxylic acids. The viscosity data as a function of polymer concentration of poly(isobutylene-alt-sodium maleate), poly(styrene-alt-sodium maleate) and poly(diisobutylene- alt-sodium maleate) show the polyelectrolyte behavior as predicted. However, the viscosity as a function of concentration of sodium maleate based copolymers with 1-alkenes; 1-octene (C8), 1-decene (C10), 1-dodecene (C12) and 1-hexene (C14) exhibit an abnormal scaling power, which might be caused by aggregation of the alkene tails to form micelles. In the last chapter, we report the rheological properties of aqueous solutions of poly(acrylic acid) and oppositely charged surfactant, dodecyl trimethylammonium bromide (C12TAB). The solution viscosity decreases as surfactant is added, partly because the polyelectrolyte wraps around the surface of the spherical surfactant micelles, shortening the effective chain length. The effects of polymer molecular weight, polymer concentration, and polymer charge have been studied with no added salt. The results are compared with the predictions of a simple model based on the scaling theory for the viscosity of dilute and unentangled semidilute polyelectrolyte solutions in good solvent. This model takes into account two effects of added surfactant. The effective chain length of the polyelectrolyte is shortened when a significant fraction of the chain wraps around micelles. Another effect is the change of solution ionic strength resulting from surfactant addition that further lowers the viscosity. The parameters used in this model are independently determined, allowing the model to make a quantitative prediction of solution viscosity with no adjustable parameters. The model is also applied to predict the decrease in viscosity of various polyelectrolyte/oppositely charged surfactant systems reported in literature. The results are in good agreement with experimental data, proving that our model applies to all polyelectrolytes mixed with oppositely charged surfactants that form spherical micelles.
Development of Alternative Rheological Measurements for DWPF Slurry Samples (U)
Energy Technology Data Exchange (ETDEWEB)
Koopman, D. c.
Rheological measurements are used to evaluate the fluid dynamic behavior of Defense Waste Processing Facility, DWPF, slurry samples. Measurements are currently made on non-radioactive simulant slurries using two state-of-the-art rheometers located at the Aiken County Technical Laboratory, ACTL. Measurements are made on plant samples using a rheometer in the Savannah River National Laboratory, SRNL, Shielded Cells facility. Low activity simulants or plant samples can be analyzed using a rheometer located in a radioactive hood in SRNL. Variations in the rheology of SB2 simulants impacted the interpretation of results obtained in a number of related studies. A separate rheological study was initiated with the following four goals: (1) Document the variations seen in the simulant slurries, both by a review of recent data, and by a search for similar samples for further study. (2) Attempt to explain the variations in rheological behavior, or, failing that, reduce the number of possible causes. In particular, to empirically check for rheometer-related variations. (3) Exploit the additional capabilities of the rheometers by developing new measurement methods to study the simulant rheological properties in new ways. (4) Formalize the rheological measurement process for DWPF-related samples into a series of protocols. This report focuses on the third and fourth goals. The emphasis of this report is on the development and formalization of rheological measurement methods used to characterize DWPF slurry samples. The organization is by rheological measurement method. Progress on the first two goals was documented in a concurrent technical report, Koopman (2005). That report focused on the types and possible causes of unusual rheological behavior in simulant slurry samples. It was organized by the sample being studied. The experimental portion of this study was performed in the period of March to April 2004. A general rheology protocol for routine DWPF slurry samples, Koopman (2004b), was drafted in addition to the companion technical report to this document.
Solid electrolytes general principles, characterization, materials, applications
Hagenmuller, Paul
Solid Electrolytes: General Principles, Characterization, Materials, Applications presents specific theories and experimental methods in the field of superionic conductors. It discusses that high ionic conductivity in solids requires specific structural and energetic conditions. It addresses the problems involved in the study and use of solid electrolytes. Some of the topics covered in the book are the introduction to the theory of solid electrolytes; macroscopic evidence for liquid nature; structural models; kinetic models; crystal structures and fast ionic conduction; interstitial motion in
Electrodeposition of Fe powder from acid electrolytes
VESNA M. MAKSIMOVIC; Ljubica J. Pavlovic; BORKA M. JOVIC; Miomir G. Pavlovic
Polarization characteristics of the electrodeposition processes of Fe powders from sulfate and chloride electrolytes and the morphology of the obtained powders were investigated. The morphology depended on the anion presence in the electrolyte but not on the current density in the investigated range. A characteristic feature of the dendritic powder with cauliflower endings obtained from sulfate electrolyte is the presence of cone-like cavities and the crystallite morphology of the powders sur...
Novel Electrolytes for Lithium Ion Batteries
Energy Technology Data Exchange (ETDEWEB)
Lucht, Brett L
We have been investigating three primary areas related to lithium ion battery electrolytes. First, we have been investigating the thermal stability of novel electrolytes for lithium ion batteries, in particular borate based salts. Second, we have been investigating novel additives to improve the calendar life of lithium ion batteries. Third, we have been investigating the thermal decomposition reactions of electrolytes for lithium-oxygen batteries.
Polymer gel electrolytes for lithium batteries
International Nuclear Information System (INIS)
The data on the most promising polymer gel electrolytes for lithium batteries published in the past decade are surveyed and described systematically. Gel electrolytes with matrices of polyethylene oxide, poly(vinylidene fluoride) and its copolymer with hexafluoropropylene, poly(methyl methacrylate), polyacrylonitrile, poly(vinyl chloride) and polyacrylates are discussed. A special section is devoted to gel electrolytes with ionic liquids as the solvents. The bibliography includes 160 references.
Electrolytic hydrogen fuel production with solid polymer electrolyte technology.
Titterington, W. A.; Fickett, A. P.
A water electrolysis technology based on a solid polymer electrolyte (SPE) concept is presented for applicability to large-scale hydrogen production in a future energy system. High cell current density operation is selected for the application, and supporting cell test performance data are presented. Demonstrated cell life data are included to support the adaptability of the SPE system to large-size hydrogen generation utility plants as needed for bulk energy storage or transmission. The inherent system advantages of the acid SPE electrolysis technology are explained. System performance predictions are made through the year 2000, along with plant capital and operating cost projections.
Intermediate Temperature Steam Electrolysis with Phosphate-Based Electrolytes
DEFF Research Database (Denmark)
Prag, Carsten Brorson
Water electrolysis for hydrogen production has been predicted to get a prominent role in the energy system of the future. Current low temperature technologies rely on expensive noble metal catalysts and high temperature systems requires special construction materials to withstand the high temperatures. Electrolysis in the intermediate temperature (IT) region (200-400 �C) is of interest as it would allow for the use of non-noble metal catalysts, due to the improved kinetics, and a wide range of construction materials as a result of the more benign temperature. At these temperatures water is supplied as steam. This work centred on the design and development of a novel steam electrolysis concept based on phosphate electrolytes capable of operating in the IT range. Central for the work was the selection and evaluation of the materials and components for the test setup and cells as well as the technological issues and challenges faced. A setup suitable for intermediate temperature electrolysis has been constructed in order to accommodate testing in the IT region. This included the evaluation of multiple generations of components such as end plates and flow plates. Chemical vapour deposition of tantalum was used to protect stainless steel components from the highly oxidative environment of the oxygen side of the electrolyser. While such protection should not be necessary on the hydrogen side, it was found that the best results were obtained using tantalum coated stainless steel flow plates not only on the oxygen side but at the hydrogen side as well. Additional key steps and components for electrolysis testing are detailed in this thesis. This includes gas diffusion layers (GDL), sealing, cell assembly techniques, test operation, electrolytes and electrocatalysts. Gas diffusion layers of carbon with a PTFE bound micro-porous layer was used for the cathode side and tantalum coated stainless steel felt was used for the anode side due to the need of corrosion protection. For the cathode side a platinum electrocatalyst was used as benchmark (Pt-black ? 8 mg/cm2) and iridium oxide was used for the anode (? 3 mg/cm2). Symmetrical cell testing for hydrogen pumping at 200 _C revealed the cathode gas diffusion layers to be unstable over time. After 60 hours, the electrode resistance was more than tripled. The most prominent reason for this was thought to be a softening of the PTFE in the cathode micro-porous layer. CsH2PO4 and Sn0.9In0.1P2O7 were used as proof-of-concept electrolytes, with emphasis on the latter electrolyte. Evaluation of electrolysis cells with these electrolytes was done with a range of tools constantly under development. These tools included regression analysis of I-V curves, reference electrode measurements and electrochemical impedance spectroscopy (EIS). While reference electrode measurements were found hard to optimise, EIS, and especially complex non-linear least-square (CNLS) fitting, was found very useful. CNLS allowed for the estimation of electrolyte resistance and polarisation resistances givinga detailed view of the novel system. Electrolysis with CsH2PO4 as electrolyte revealed a need for steam on both cathode and anode in order to prevent dehydration of the electrolyte. Additional stabilisation in the form of SiC fibres was found to increase longevity considerably. Highest achieved current density was 60 mA/cm2 at 2.0 V and 250 �C. Measurements using Sn0.9In0.1P2O7 as electrolyte, Pt black as cathode electrocatalyst and IrO2 as anode electrocatalyst gave current densities as high as 313 mA/cm2 at 1.9 V and 200 �C. The stability of the electrolyte was found to be high at 200 �C and a water partial pressure of 0.05 atm. For stabilisation of the electrolyte at 250 �C a higher water partial pressure is needed. Variation of temperature from 200-250 �C showed both signs of activation of electrode processes and electrode degradation. Efforts were done to optimise the synthesis of Sn0.9In0.1P2O7 in order to establish a reproducible synthesis procedure. The synthesis used in this work required two heat
Ion transport phenomena in polymeric electrolytes
International Nuclear Information System (INIS)
The aim of the present work is to generalize an ion transport phenomena observed in composite polymeric electrolytes using the previously developed models as well as design a new approach which would be helpful in describing changes in conductivity and lithium ion transference numbers occurring upon addition of fillers to polymeric electrolytes. The concept is based on the observation of changes in ionic associations in the polymeric electrolytes studied in a wide salt concentration range. The idea is illustrated by the results coming from a variety of electrochemical and structural data obtained for composite electrolytes containing specially designed inorganic and organic fillers
Ion transport phenomena in polymeric electrolytes
Energy Technology Data Exchange (ETDEWEB)
Ciosek, M.; Sannier, L.; Siekierski, M.; Wieczorek, W. [Warsaw University of Technology, Faculty of Chemistry, Noakowskiego 3, 00-664 Warsaw (Poland); Golodnitsky, D.; Peled, E. [School of Chemistry, Tel Aviv University, Tel Aviv 69978 (Israel); Scrosati, B. [Dipartimento di Chimica, Universita di Roma ' ' La Sapienza' ' , P. le A. Moro 4, 00185 Rome (Italy); Glowinkowski, S. [Faculty of Physics, Adam Mickiewicz University, Ulmultowska 86, 61-614 Poznan (Poland)
The aim of the present work is to generalize an ion transport phenomena observed in composite polymeric electrolytes using the previously developed models as well as design a new approach which would be helpful in describing changes in conductivity and lithium ion transference numbers occurring upon addition of fillers to polymeric electrolytes. The concept is based on the observation of changes in ionic associations in the polymeric electrolytes studied in a wide salt concentration range. The idea is illustrated by the results coming from a variety of electrochemical and structural data obtained for composite electrolytes containing specially designed inorganic and organic fillers. (author)
Electrodeposition of Fe powder from acid electrolytes
Directory of Open Access Journals (Sweden)
Full Text Available Polarization characteristics of the electrodeposition processes of Fe powders from sulfate and chloride electrolytes and the morphology of the obtained powders were investigated. The morphology depended on the anion presence in the electrolyte but not on the current density in the investigated range. A characteristic feature of the dendritic powder with cauliflower endings obtained from sulfate electrolyte is the presence of cone-like cavities and the crystallite morphology of the powders surface. On the other hand, Fe powders electrodeposited from chloride electrolyte appear in the form of agglomerates. A soap solution treatment applied as a method of washing and drying provides good protection from oxidation of the powders.
Handbook of Aqueous Electrolyte Thermodynamics Theory & Application
Zemaitis, Joseph F; Rafal, Marshall
Expertise in electrolyte systems has become increasingly important in traditional CPI operations, as well as in oil/gas exploration and production. This book is the source for predicting electrolyte systems behavior, an indispensable "do-it-yourself" guide, with a blueprint for formulating predictive mathematical electrolyte models, recommended tabular values to use in these models, and annotated bibliographies. The final chapter is a general recipe for formulating complete predictive models for electrolytes, along with a series of worked illustrative examples. It can serve as a usef
Rebalancing electrolytes in redox flow battery systems
Chang, On Kok; Pham, Ai Quoc
Embodiments of redox flow battery rebalancing systems include a system for reacting an unbalanced flow battery electrolyte with a rebalance electrolyte in a first reaction cell. In some embodiments, the rebalance electrolyte may contain ferrous iron (Fe.sup.2+) which may be oxidized to ferric iron (Fe.sup.3+) in the first reaction cell. The reducing ability of the rebalance reactant may be restored in a second rebalance cell that is configured to reduce the ferric iron in the rebalance electrolyte back into ferrous iron through a reaction with metallic iron.
Rheological changes in irradiated chicken eggs
International Nuclear Information System (INIS)
Pathogenic bacteria may cause foodborne illnesses. Humans may introduce pathogens into foods during production, processing, distribution and or preparation. Some of these microorganisms are able to survive conventional preservation treatments. Heat pasteurization, which is a well established and satisfactory means of decontamination/disinfection of liquid foods, cannot efficiently achieve a similar objective for solid foods. Extensive work carried out worldwide has shown that irradiation is efficient in eradicating foodborne pathogens like Salmonella spp. that can contaminate poultry products. In this work Co-60 gamma irradiation was applied to samples of industrial powder white, yolk and whole egg at doses between 0 and 25 kGy. Samples were rehydrated and the viscosity measured in a Brookfield viscosimeter, model DV III at 5, 15 and 25 degree sign C. The rheological behaviour among the various kinds of samples were markedly different. Irradiation with doses up to 5 kGy, known to reduced bacterial contamination to non-detectable levels, showed almost no variation of viscosity of irradiated egg white samples. On the other hand, whole or yolk egg samples showed some changes in rheological properties depending on the dose level, showing the predominance of whether polimerization or degradation as a result of the irradiation. Additionally, irradiation of yolk egg powder reduced yolk color as a function of the irradiation exposure implemented. The importance of these resulimplemented. The importance of these results are discussed in terms of possible industrial applications
Improving feed slurry rheology by colloidal techniques
International Nuclear Information System (INIS)
Pacific Northwest Laboratory (PSN) has investigated three colloidal techniques in the laboratory to improve the sedimentation and flowability of Hanford simulated (nonradioactive) current acid waste (CAW) melter feed slurry: polymer-induced bridging flocculation; manipulating glass former (raw SiO2 or frit) particle size; and alteration of nitric acid content. All three methods proved successful in improving the rheology of the simulated CAW feed. This initially had exhibited nearly worst-case flow and clogging properties, but was transformed into a flowable, resuspendable (nonclogging) feed. While each has advantages and disadvantages, the following three specific alternatives proved successful: addition of a polyelectrolyte in 2000 ppM concentration to feed slurry; substitution of a 49 wt % SiO2 colloidal suspension (approx. 10-micron particle size) for the -325 mesh (less than or equal to 44-micron particle size) raw-chemical SiO2; and increase of nitric acid content from the reference 1.06 M to optimum 1.35 M. The first method, polymer-induced bridging flocculation, results in a high sediment volume, nonclogging CAW feed. The second method, involving the use of colloidal silica particles results in a nonsedimenting feed that when left unagitated forms a gel. The third method, increase in feed acidity, results in a highly resuspendable (nonclogging) melter feed. Further research is therefore required to determine which of the three alternatives is the preferred method of achieving rheological control of CAW melter feeds
Study of the rheological properties of oil
Energy Technology Data Exchange (ETDEWEB)
Jewulski, J.
The author describes industrial research into the process of disturbing the thixotropic structure of oil in well L-3 during constant oil coagulation inside the ''Rheostat'' rotating cylindrical viscosity meter. This oil, containing paraffin, has a high viscosity and corresponds to the chemical classification for pseudo water plastic thixotropic flowing liquid. This research was conducted at temperatures of 15,20,25, and 30 degrees C. The final time period is determined for the disintegration of the oil structure, during which almost no indicator changes are detected by industrial metering devices. This process of disintegration was viewed by the author as a breakdown of the thixotropic structure during the given rate of coagulation. Metering results were approximated and found to be most significant in non-stationary processes over a relatively short period of time. The rheological curve is then often replaced by a straight angle. This article also examines certain factors in the transport of such oil and trunklines and the resulting effects upon that oil's rheological composition.
Vortex jamming in superconductors and granular rheology
International Nuclear Information System (INIS)
We demonstrate that a highly frustrated anisotropic Josephson junction array (JJA) on a square lattice exhibits a zero-temperature jamming transition, which shares much in common with those in granular systems. Anisotropy of the Josephson couplings along the horizontal and vertical directions plays roles similar to normal load or density in granular systems. We studied numerically static and dynamic response of the system against shear, i.e. injection of external electric current at zero temperature. Current-voltage curves at various strength of the anisotropy exhibit universal scaling features around the jamming point much as do the flow curves in granular rheology, shear-stress versus shear-rate. It turns out that at zero temperature the jamming transition occurs right at the isotropic coupling and anisotropic JJA behaves as exotic fragile vortex matter: it behaves as a superconductor (vortex glass) in one direction, whereas it is a normal conductor (vortex liquid) in the other direction even at zero temperature. Furthermore, we find a variant of the theoretical model for the anisotropic JJA quantitatively reproduces universal master flow-curves of the granular systems. Our results suggest an unexpected common paradigm stretching over seemingly unrelated fields-the rheology of soft materials and superconductivity.
Rheological characterization of Poloxamer 407 nimesulide gels
Directory of Open Access Journals (Sweden)
M. N. Freitas
Full Text Available The thermal gelling property of Poloxamer 407- nimesulide gels was characterized by rheological studies. Nimesulide, a local anti-inflammatory and anesthetic drug used for the treatment of acute and chronic pain, has a short duration of action and a long-acting single-dose injection would be of clinical importance. Thus a poloxamer 407 gel applied intramuscularly could prolong the release and action of nimesulide. In this study, aqueous gels with nimesulide, containing three different concentrations of Poloxamer 407, were prepared. Viscosity measurements were performed by rheologial studies to obtain the optimal sol-gel transition temperature . Poloxamer 407 gels are pseudoplastic and viscoelastic materials, which have an elastic modulus (G', characteristic of the solid, and a viscous modulus (G'', characteristic of the liquid material. Moreover, being pseudoplastic gels, when they are deformed by shearing, their viscosity decreases. Increase of the polymer concentration increased the viscosity of the gels, which could affect the releasing process of nimesulide. Furthermore, the presence of nimesulide led to a lowering of the sol-gel transition temperature. Keywords: Poloxamer 407 gels; nimesulide; rheological characterization; viscosity; sol-gel transition temperature.
Shear rheology of a cell monolayer
International Nuclear Information System (INIS)
We report a systematic investigation of the mechanical properties of fibroblast cells using a novel cell monolayer rheology (CMR) technique. The new technique provides quantitative rheological parameters averaged over ?106 cells making the experiments highly reproducible. Using this method, we are able to explore a broad range of cell responses not accessible using other present day techniques. We perform harmonic oscillation experiments and step shear or step stress experiments to reveal different viscoelastic regimes. The evolution of the live cells under externally imposed cyclic loading and unloading is also studied. Remarkably, the initially nonlinear response becomes linear at long timescales as well as at large amplitudes. Within the explored rates, nonlinear behaviour is only revealed by the effect of a nonzero average stress on the response to small, fast deformations. When the cell cytoskeletal crosslinks are made permanent using a fixing agent, the large amplitude linear response disappears and the cells exhibit a stress stiffening response instead. This result shows that the dynamic nature of the cross-links and/or filaments is responsible for the linear stress-strain response seen under large deformations. We rule out the involvement of myosin motors in this using the inhibitor drug blebbistatin. These experiments provide a broad framework for understanding the mechanical responses of the cortical actin cytoskeleton of fibroblasts to differen cytoskeleton of fibroblasts to different imposed mechanical stimuli
Synthesis and characterization of low cost magnetorheological (MR) fluids
Sukhwani, V. K.; Hirani, H.
Magnetorheological fluids have great potential for engineering applications due to their variable rheological behavior. These fluids find applications in dampers, brakes, shock absorbers, and engine mounts. However their relatively high cost (approximately US600 per liter) limits their wide usage. Most commonly used magnetic material "Carbonyl iron" cost more than 90% of the MR fluid cost. Therefore for commercial viability of these fluids there is need of alternative economical magnetic material. In the present work synthesis of MR fluid has been attempted with objective to produce low cost MR fluid with high sedimentation stability and greater yield stress. In order to reduce the cost, economical electrolytic Iron powder (US 10 per Kg) has been used. Iron powder of relatively larger size (300 Mesh) has been ball milled to reduce their size to few microns (1 to 10 microns). Three different compositions have been prepared and compared for MR effect produced and stability. All have same base fluid (Synthetic oil) and same magnetic phase i.e. Iron particles but they have different additives. First preparation involves organic additives Polydimethylsiloxane (PDMS) and Stearic acid. Other two preparations involve use of two environmental friendly low-priced green additives guar gum (US 2 per Kg) and xanthan gum (US 12 per Kg) respectively. Magnetic properties of Iron particles have been measured by Vibrating Sample Magnetometer (VSM). Morphology of Iron particles and additives guar gum and xanthan gum has been examined by Scanning Electron Microscopy (SEM) and Particles Size Distribution (PSD) has been determined using Particle size analyzer. Microscopic images of particles, MH plots and stability of synthesized MR fluids have been reported. The prepared low cost MR fluids showed promising performance and can be effectively used for engineering applications demanding controllability in operations.
Review Of Rheology Modifiers For Hanford Waste
Energy Technology Data Exchange (ETDEWEB)
Pareizs, J. M.
As part of Savannah River National Laboratory (SRNL)'s strategic development scope for the Department of Energy - Office of River Protection (DOE-ORP) Hanford Tank Waste Treatment and Immobilization Plant (WTP) waste feed acceptance and product qualification scope, the SRNL has been requested to recommend candidate rheology modifiers to be evaluated to adjust slurry properties in the Hanford Tank Farm. SRNL has performed extensive testing of rheology modifiers for use with Defense Waste Processing Facility (DWPF) simulated melter feed - a high undissolved solids (UDS) mixture of simulated Savannah River Site (SRS) Tank Farm sludge, nitric and formic acids, and glass frit. A much smaller set of evaluations with Hanford simulated waste have also been completed. This report summarizes past work and recommends modifiers for further evaluation with Hanford simulated wastes followed by verification with actual waste samples. Based on the review of available data, a few compounds/systems appear to hold the most promise. For all types of evaluated simulated wastes (caustic Handford tank waste and DWPF processing samples with pH ranging from slightly acidic to slightly caustic), polyacrylic acid had positive impacts on rheology. Citric acid also showed improvement in yield stress on a wide variety of samples. It is recommended that both polyacrylic acid and citric acid be further evaluated as rheology modifiers for Hanford waste. These materials are weak organic acids with the following potential issues: The acidic nature of the modifiers may impact waste pH, if added in very large doses. If pH is significantly reduced by the modifier addition, dissolution of UDS and increased corrosion of tanks, piping, pumps, and other process equipment could occur. Smaller shifts in pH could reduce aluminum solubility, which would be expected to increase the yield stress of the sludge. Therefore, it is expected that use of an acidic modifier would be limited to concentrations that do not appreciably change the pH of the waste; Organics are typically reductants and could impact glass REDOX if not accounted for in the reductant addition calculations; Stability of the modifiers in a caustic, radioactive environment is not known, but some of the modifiers tested were specifically designed to withstand caustic conditions; These acids will add to the total organic carbon content of the wastes. Radiolytic decomposition of the acids could result in organic and hydrogen gas generation. These potential impacts must be addressed in future studies with simulants representative of real waste and finally with tests using actual waste based on the rheology differences seen between SRS simulants and actual waste. The only non-organic modifier evaluated was sodium metasilicate. Further evaluation of this modifier is recommended if a reducing modifier is a concern.
Ultrafast Li Electrolytes Based on Abundant Elements: Li$_{10}$SnP$_2$S$_{12}$ and Li$_{11}$Si$_2$PS$_{12}$
Kuhn, Alexander; Gerbig, Oliver; Zhu, Changbao; Falkenberga, Frank; Maier, Joachim; Lotsch, Bettina V.
We report on the synthesis and characterization of two solid electrolytes, Li$_{10}$SnP$_2$S$_{12}$ and Li$_{11}$Si$_2$PS$_{12}$, which are based exclusively on abundant elements. Both compounds feature extremely high Li ion diffusivities, with the Si-based material even surpassing the present record holder, the related electrolyte Li$_{10}$GeP$_2$S$_{12}$. The structure and dynamics were studied with multiple complementary techniques and the macroscopic diffusion could be t...
Supercapacitor behavior of ?-MnMoO{sub 4} nanorods on different electrolytes
Energy Technology Data Exchange (ETDEWEB)
Purushothaman, K.K., E-mail: email@example.com [Department of Physics, TRP Engineering College (SRM Group), Irungalur, Trichy, Tamilnadu (India); Cuba, M. [Department of Physics, Gandhigram Rural Institute � Deemed University, Gandhigram, Tamilnadu (India); Muralidharan, G., E-mail: firstname.lastname@example.com [Department of Physics, Gandhigram Rural Institute � Deemed University, Gandhigram, Tamilnadu (India)
Graphical abstract: SEM image of ?-MnMoO{sub 4} nanorods on FTO substrate. Highlights: ? Synthesis of ?-MnMoO{sub 4} nanorods by spin coating method. ? First study on the effect of electrolyte on the pseudocapacitance behavior. ? ?-MnMoO{sub 4} nanorods exhibit maximum specific capacitance of 998 F/g. ? At higher scan rates p-TSA electrolyte exhibits superior capacitive behavior. -- Abstract: ?-MnMoO{sub 4} nanorods were prepared on conducting glass substrate via sol�gel spin coating method at the optimum doping level. The effect of electrolyte on the pseudocapacitance behavior of the ?-MnMoO{sub 4} nanorods was studied using para toluene sulfonic acid (p-TSA), sulfuric acid (H{sub 2}SO{sub 4}) and hydrochloric acid (HCl) as electrolytes. X-ray diffraction analysis reveals the formation of ?-MnMoO{sub 4} in monoclinic phase. FTIR spectra contain vibrational bands associated with Mo=O, M�O and Mo�O�Mo bonds. SEM image reveals the formation of nanorods. Supercapacitor behavior has been studied using cyclic voltammetry (CV) analysis. ?-MnMoO{sub 4} nanorods exhibit maximum specific capacitance of 998 F/g at a scan rate of 5 mV/s in H{sub 2}SO{sub 4} electrolyte while a specific capacitance of 784 F/g and 530 F/g have been obtained using p-TSA and HCl electrolytes, respectively. At higher scan rates p-TSA electrolyte exhibits superior capacitive behavior than H{sub 2}SO{sub 4}.
Improvement by heating of the electronic conductivity of cobalt spinel phases, electrochemically synthesized in various electrolytes
International Nuclear Information System (INIS)
The nature of the alkaline electrolyte (based on KOH, NaOH, LiOH), in which Co3O4 spinel type phases are synthesized by electrooxidation of CoO, is shown to play a key role on the composition, the structure and the electronic conductivity of the materials. In the materials, prepared in pure LiOH electrolyte or in mixed ternary electrolyte (KOH, NaOH, LiOH), Co4+ ions are present in the octahedral framework, which entails electronic delocalization in the cobalt T2g band and a high conductivity. The structure of the sample, synthesized in KOH, is on the opposite closer to that of ideal Co3O4, with only Co3+ in the octahedral sublattice, which leads to a semi-conducting behavior. Whatever the initial material, a thermal treatment induces an increase of the Co4+/Co3+ ratio in the octahedral network, resulting in a significant increase of the electronic conductivity. - Graphical abstract: In 'Co3O4' type spinel phases synthesized by eleectrooxidation, the nature of the alkaline electrolyte allows to monitor the amounts of hydrogen and lithium, inserted in spinel framework and therefore the electronic conductivity. Whatever the initial synthesis electrolyte, a moderate thermal treatment of the materials induces a significant increase of the electronic conductivity, due to a structural reorganization (illustrated by the evolution of the cell parameter) andy the evolution of the cell parameter) and an increase of the Co4+/Co3+ ratio in the octahedral framework.
Emission properties of electrolytic rhenium
International Nuclear Information System (INIS)
Studied are emission properties of a tubular cathode made of a chloride rhenium-containing melt by the galvanoplastic method. The vacuum density of the sample and a possibility of fusing it with niobium by means of electron-beam welding have been shown. The electron work function is found to make 4.94+-0.05 eV. The structure of the sample has been shown to be thermally stable. The experiments show that electrolyte rhenium can be applied as a material for cathodes of thermo-emission converters. There are possibilities of considerable improvement of its properties by precipitation of layers with highly perfect texture (0001)
Electrolytic entorhinal lesions cause seizures.
Dasheiff, R M; McNamara, J O
The entorhinal cortex is a key site of interneuronal communication between a variety of cortical and subcortical areas and hippocampal formation. Lesioning the entorhinal cortex is commonly used in studies of the hippocampal formation, animal behavior and neuronal plasticity. We have found that electrolytic destruction of the entorhinal cortex consistently produces limbic seizure activity in rats. The propensity of lesions in this area for producing seizure activity may facilitate insights into the normal function of this network of neural connections. This unexpected phenomenon represents a potential confounding variable for all researchers using this method for making brain lesions. PMID:7055687
Synthesis of hydrophobically modified polyacrylamide in inverse miniemulsion
Kobitskaya, Elena
In this thesis, two important aspects have been considered: the development and characterization of the miniemulsion technique for the synthesis of hydrophobically modified polyacrylamides, and the investigation of their associative and rheological properties. The synthesis of HM polyacrylamides in inverse miniemulsion was initially optimized by free-radical polymerization of acrylamide initiated by AIBN. The possibility of copolymerization of monomers with different hydrophilicities was show...
The electrically conductive function of high-molecular weight poly(ethylene oxide) in polymer gel electrolytes used for dye-sensitized solar cells.
Shi, Yantao; Zhan, Chun; Wang, Liduo; Ma, Beibei; Gao, Rui; Zhu, Yifeng; Qiu, Yong
The electrically conductive function of high-molecular weight poly(ethylene oxide) (PEO) (M(w) = 2 x 10(6) g mol(-1)) was investigated when it was used to gelate liquid electrolyte to fabricate a series of polymer gel electrolytes for dye-sensitized solar cells (DSCs). With the PEO weight ratio increasing from 2.5 to 15.0% (vs. liquid electrolyte), rheological behavior measurement showed that the viscosity of the polymer gel electrolytes increased ca 465 times. However, it was observed by steady-state voltammetry and electrochemical impedance spectra (EIS) measurements that the diffusion coefficient of I(3)(-)/I(-) decreased constantly while the conductivity of the polymer gel electrolytes increased initially and then decreased. These two inconsistent behaviours showed that the mobility of Li(+) was enhanced by PEO. EIS measurement revealed that the internal resistance of the DSCs were reduced since the enhanced mobility of Li(+) was helpful for the transport of electrons within the TiO(2) film through an ambipolar diffusion mechanism. When these polymer gel electrolytes were used to assemble DSCs, the conversion efficiency of DSCs increased continuously until it reached its maximum as the PEO weight ratio increased from 2.5 to 10.0%. By optimizing the dye adsorbing time and the thickness of the TiO(2) film, a quasi-solid DSC based on a polymer gel electrolyte with a PEO weight ratio of 10.0% showed a considerable conversion efficiency, 6.12 and 10.11% under 100 and 30 mW cm(-2) illumination, respectively. Finally, a stability test indicated that the more PEO was added into the polymer gel electrolytes, the better stability was obtained for the corresponding DSCs. PMID:19458824
Study and development of a hydrogen/oxygen fuel cell in solid polymer electrolyte technology
Energy Technology Data Exchange (ETDEWEB)
Mosdale, R.
The hydrogen/oxygen fuel cell appears today as the best candidate to the replacing of the internal combustion engine for automobile traction. This system uses the non explosive electrochemical recombination of hydrogen and oxygen. It is a clean generator whom only reactive product is water. This thesis shows a theoretical study of this system, the synthesis of different kinds of used electrodes and finally an analysis of water movements in polymer electrolyte by different original technologies. 70 refs., 73 figs., 15 tabs.
Acoustic Modeling of a 3-Layered Panel Incorporating Electro-Rheological/ Magneto-Rheological (EMR) Fluids
Nader Mohammadi
Applications or Magneto-Rheological (MR) fluids as typical smart materials have been widely investigated over the past decades (since their introduction in 40�s). The special applications of these materials as a means of noise suppression are not yet investigated. Constrained Layer Damping (CLD) sheets can be realized by incorporating EMR (ER/MR) materials. In this way, This notion has been introduced for semi-active vibration control problems.teristics of these composite sheets enab...
Rheological study of chitosan and its blends: An overview
Directory of Open Access Journals (Sweden)
Esam A. El-hefian
Full Text Available Chitosan, a modified natural carbohydrate polymer derived from carapaces of crabs and shrimps, has received a great deal of attention for its applications in diverse fields owing to its biodegradability, biocompatibility, non-toxicity and anti-bacterial property. The wide-ranging applications involve a broad spectrum of characterisation techniques and rheology represents one technique of growing importance in this field. This paper is an attempt to review the latest development in the rheology of chitosan, either on its own or associated with other materials, including the parameters that strongly influence its rheological behaviour such as concentration, pH and temperature.
Rheology and interfacial tension of biopolymers
Kandadai, Madhuvanthi A.
The rheology and interfacial tension of biomaterials are important factors governing their potential use in biomedical applications. This dissertation presents a study of the rheology and interfacial tension of three very different biomaterials: (1) A hydrophobically modified Hyaluronic acid (HA) with polypeptide side chains, (2) Actin fibers and (3) a highly hydrophobic fluoroalkane, Perfluoropentane, and the effect of various surfactants and their mixtures on lowering its interfacial tension in an aqueous interface. In Chapter 1, we present a description of the properties and applications of these materials and a detailed literature review relevant to our studies to better understand the motivation of our work. In Chapter 2 we describe the techniques used for our studies. In Chapter 3, we present our studies on the hydrophobically modified HA with polyleucine side chains and compare them to unmodified HA of same or similar backbone molecular weights. We found a significantly enhanced viscosity for the modified HA compared to unmodified HA at the same concentration. We also found a viscoelastic behavior that was dependent on the concentration of the solution and grafting ratio of the hydrophobic side chains. The associative thickening properties of modified HA investigated with various rheological experiments and simulation results are presented in this chapter. In Chapter 4, we present our studies on the properties of actin fibers. We used a novel microrheometer VROC(TM) (Viscometer-rheometer-on-a-chip) for studying actin fibers at very high shear rates. We show that at very high shear rats, the actin filaments show irreversible network breakdown. We also studied the surface tension of actin filaments and monomer solutions at the interface with air and report induction times of these materials. In Chapter 5, we study the interfacial tension of a highly hydrophobic fluoroalkane, Perfluoropentane, in the presence of different surfactants and their mixtures. The surfactants studied are commonly used amphiphilic biopolymers polyethylene oxide-co-polylactic acid (PEO-PLA) and polyethylene oxide-co-poly-epsilon-caprolactone (PEO-PCL), and cetyl trimethyl ammonium bromide (CTAB). A significant lowering of the interfacial tension was observed with all these surfactants with the greatest lowering in the presence of CTAB.
Rheological properties of cupuassu and cocoa fats
Directory of Open Access Journals (Sweden)
Gioielli, L. A.
Full Text Available Cocoa butter is an important ingredient in chocolate formulation as it dictates the main properties (texture, sensation in the mouth, and gloss. In the food industry, the texture of fat-containing products strongly depends on the macroscopic properties of the fat network formed within the finished product. Cupuassu ( Theobroma grandiflorum , Sterculiaceae is an Amazonian native fruit and the seeds can be used to derive a cocoa butter like product. In general, these fats are similar to those of cocoa, although they are different in some physical properties. The objective of this study was to analyze several properties of the cupuassu fat and cocoa butter (crystal formation at 25 ° C, rheological properties, and fatty acid composition and mixtures between the two fats (rheological properties, in order to understand the behavior of these fats for their use in chocolate products. Fat flow was described using common rheological models ( Newton , Power Law, Casson and Bingham plastic.La manteca de cacao es un ingrediente muy importante en la formulaci�n de chocolates y es responsable de la mayor parte de sus propiedades (textura, palatibilidad y brillo. En la industria de alimentos, la textura de productos que contienen grasa depende enormemente de las propiedades macrosc�picas de la red cristalina de la grasa en el producto final. El cupua�u es una fruta nativa de la regi�n amaz�nica y sus semillas pueden ser usadas para obtener una grasa semejante a la manteca de cacao. En general, esta grasa es similar a la manteca de cacao, pero difiere en algunas de sus propiedades fisicas . El objetivo de este estudio fue analizar algunas propiedades de la grasa de cupua�u y de la manteca de cacao (formaci�n de cristales a 25 °C, propiedades reol�gicas y composici�n en �cidos grasos y de algunas mezclas entre las dos grasas (propiedades reol�gicas, a fin de conocer el comportamiento de estas grasas para ser usadas en productos de la industria del chocolate. El flujo de la grasa se ha descrito utilizando modelos reol�gicos comunes (Newton, ley de la potencia, Casson y pl�stico de Bingham.
Highly flexible, proton-conductive silicate glass electrolytes for medium-temperature/low-humidity proton exchange membrane fuel cells.
Lee, Hyeon-Ji; Kim, Jung-Hwan; Won, Ji-Hye; Lim, Jun-Muk; Hong, Young Taik; Lee, Sang-Young
We demonstrate highly flexible, proton-conductive silicate glass electrolytes integrated with polyimide (PI) nonwoven fabrics (referred to as "b-SS glass electrolytes") for potential use in medium-temperature/low-humidity proton exchange membrane fuel cells (PEMFCs). The b-SS glass electrolytes are fabricated via in situ sol-gel synthesis of 3-trihydroxysilyl-1-propanesulfonic acid (THPSA)/3-glycidyloxypropyl trimethoxysilane (GPTMS) mixtures inside PI nonwoven substrates that serve as a porous reinforcing framework. Owing to this structural uniqueness, the b-SS glass electrolytes provide noticeable improvements in mechanical bendability and membrane thickness, in comparison to typical bulk silicate glass electrolytes that are thick and easily fragile. Another salient feature of the b-SS glass electrolytes is the excellent proton conductivity at harsh measurement conditions of medium temperature/low humidity, which is highly important for PEMFC-powered electric vehicle applications. This beneficial performance is attributed to the presence of a highly interconnected, proton-conductive (THPSA/GPTMS-based) silicate glass matrix in the PI reinforcing framework. Notably, the b-SS glass electrolyte synthesized from THPSA/GPTMS = 9/1 (mol/mol) exhibits a higher proton conductivity than water-swollen sulfonated polymer electrolyte membranes (here, sulfonated poly(arylene ether sulfone) and Nafion are chosen as control samples). This intriguing behavior in the proton conductivity of the b-SS glass electrolytes is discussed in great detail by considering its structural novelty and Grotthuss mechanism-driven proton migration that is strongly affected by ion exchange capacity (IEC) values and also state of water. PMID:23672268
F4U production by electrolytic reduction
International Nuclear Information System (INIS)
As a part of the nuclear fuel cycle program developed at the Spanish Atomic Energy Commission it has been studied the electrolytic reduction of U-VI to U-IV. The effect of the materials, electrolyte concentration, pH, current density, cell size and laboratory scale production is studied. The Pilot Plant and the production data are also described. (Author) 18 refs
Method of regenerating electrolytic decontaminating liquid
International Nuclear Information System (INIS)
Purpose: To reduce the amount of secondary wastes and decrease the cost by the recovery of a liquid electrolyte, by regenerating the degraded liquid electrolyte used for the metal decontamination while utilizing the diffusion osmosis and diaphragm electrolysis. Method: When metal wastes produced from a nuclear power plant are electrolytically decontaminated, contaminating materials on the metal surfaces are transferred into the liquid electrolyte. The electrolytic decontaminating liquid is introduced into the diffusion osmotic vessel and separated into acidic ingredients (H2SO4, H3PO4) and metal ion components. Then, the acid components are transferred to a portion between the cation exchange membrane and anion exchange membrane in the diaphragm electrolytic cell, and the metal ion components are transferred to a portion between the anionic exchange membranes and the cathode. The anions contained so far in the metal ions (SO42-, PO42-) are accumulated between the anionic exchange membrane and the cationic ion exchange membrane and then returned to the electrolytic cell after having been converted into acid components (H2SO4, H3PO4) as the liquid electrolyte. While on the other hand, metal ions are formed into metal hydroxides to discharge and then discharged out of the system. (Kamimura, M.)
Plasma electrolytic oxidation of metals
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Stojadinovi? Stevan
Full Text Available In this lecture results of the investigation of plasma electrolytic oxidation (PEO process on some metals (aluminum, titanium, tantalum, magnesium, and zirconium were presented. Whole process involves anodizing metals above the dielectric breakdown voltage where numerous micro-discharges are generated continuously over the coating surface. For the characterization of PEO process optical emission spectroscopy and real-time imaging were used. These investigations enabled the determination of electron temperature, electron number density, spatial density of micro-discharges, the active surface covered by micro-discharges, and dimensional distribution of micro-discharges at various stages of PEO process. Special attention was focused on the results of the study of the morphology, chemical, and phase composition of oxide layers obtained by PEO process on aluminum, tantalum, and titanium in electrolytes containing tungsten. Physicochemical methodes: atomic force microscopy (AFM, scanning electron microscopy (SEM-EDS, x-ray diffraction (XRD, x-ray photoelectron spectroscopy (XPS, and Raman spectroscopy served as tools for examining obtained oxide coatings. Also, the application of the obtained oxide coatings, especially the application of TiO2/WO3 coatings in photocatalysis, were discussed.
Rheology and lubricity of hyaluronic acid
Liang, Jing; Krause, Wendy E.
The polyelectrolyte hyaluronic acid (HA, hyaluronan) is an important component in synovial fluid (i.e., the fluid that lubricates our freely moving joints). Its presence results in highly viscoelastic solutions. In comparison to healthy synovial fluid, diseased fluid has a reduced viscosity and loss of lubricity. In osteoarthritis the reduction in viscosity results from a decline in both the molecular weight and concentration of HA. In our investigation, we attempt to correlate the rheological properties of HA solutions to changes in lubrication and wear. A nanoindenter will be used to evaluate the coefficient of friction and wear properties between the nanoindenter tip and ultrahigh molecular weight polyethylene in both the presence and absence of a thin film of HA solution.
Rheological and microstructural properties of Irradiated starch
International Nuclear Information System (INIS)
Gamma irradiation ia s fast and efficient method to improve the functional properties of straches. Wheat and potato starches were submitted, in the present study, at 3,5,10 and 20 kGy radiation dose. The changes induced by irradiation on the rheological properties of these starches showed a decrease in the viscosity with increasing radiation dose. Chemicals bond's hydrolysis has been induced by free radicals that have been identified by EPR. Wheat starch presents five EPR signals after irradiation, whiles potato starch has a weak EPR signal. On the other hand, irradiation caused decrease in amylose content. This decrease is more pronounced in potato starch. Dry irradiated starch's MEB revealed no change in the shape, size and distribution of the granules. While, the observation of wheat starch allowed the complete disappearance of the granular structure and the dissolution of its macromolecules after irradiation which justifies the significant decrease in wheat starch's viscosity irradiated at 20 kGy.
Rheological effects in roll coating of paints
Scientific Electronic Library Online (English)
F., Varela L�pez; M., Rosen.
Full Text Available the aim of this work is the study of the problems that arise during roll coating application of paints on steel sheets. We put in evidence the particular effects due to the non-Newtonian properties of these fluids. At speeds above a certain critical value, the flow of paint through the applicator su [...] ffers a hydrodynamical instability called ribbing, which generates a patterned interface on the film applied. Threshold of instability as well as waveform of the pattern is function of rheological properties of paints as well as surface tension. Thixotropy of paints as well as shear-thinning behaviour has been determined for several industrial paints used in the steel industry, and correlated with levelling performance after application.
Impact of Helicobacter Pylori on Mucus Rheology
Celli, Jonathan; Keates, Sarah; Kelly, Ciaran; Turner, Bradley; Bansil, Rama; Erramilli, Shyamsunder
It is well known that the viscoelastic properties of gastric mucin are crucial to the protection of the lining of the stomach against its own acidic secretions and other agents. Helicobacter Pylori, a rod shaped, gram-negative bacteria that dwells in the mucus layer of approximately 50% of the world's population is a class I carcinogen and is associated with gastric ulcers and severe gastritis. The structural damage to the mucus layer caused by H. Pylori is an important aspect of infection with this bacteria. We are examining the impact of H. Pylori on mucin and mucus rheology quantitatively using a combination of dynamic light scattering and multiple particle tracking experiments. Video microscopy data will also be presented on the motility of this bacteria in mucin at different pH and in other viscoelastic gels.
The Rheological Property of Potato Starch Adhesives
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Junjun Liu
Full Text Available The main goal of this study was to use potato starch in the production of environmentally sound adhesives. �Three-formaldehyde glue� pollutes the environment and harms to human health strongly, which widely used for wood-based panels preparation. Environment-friendly potato starch adhesives were prepared using method of oxidation-gelatinization, insteading of the three formaldehyde glue. The effects of the quality ratio of starch and water, temperature and shear rate on the apparent viscosity of the adhesive were studied. The rheological eigenvalue of apparent viscosity was studied through nonlinear regression. The results showed that the apparent viscosity of potato starch adhesives decreased with the increasing of temperature; the apparent viscosity decreased slowly with the increasing of rotor speed; the phenomenon of shear thinning appeared within potato starch adhesives which was pseudo-plastic fluids. Potato starch adhesives with characteristics of non-toxic, no smell and pollution could be applied in interior and upscale packaging.
Marangoni forces in interfacial dilatational rheology
Elfring, Gwynn; Leal, Gary; Squires, Todd
Many methods for measuring the mechanical properties of fluid interfaces involve generating a flow at the interface with both dilatation and shear, such as by translating a probe through a fluid interface. We examine here the force on a translating probe at an interface laden with a soluble surfactant, that exhibits Newtonian interfacial rheology. We assume that the interface is neither incompressible nor equilibrated. We look at the effects on the force measured by a probe due to small deviations in the concentration field which result from the dilatational flows induced by the probe. In particular we discuss the coupling of concentration relaxation and surface viscosity on Marangoni forces generated by the interfacial flows.
Rheological properties of sodium smectite clay
International Nuclear Information System (INIS)
The rheological properties of Na-smectite Mx-80 have been investigated by various laboratory tests. The investigations include determination of the hydraulic conductivity, the undrained stress-strain-strength properties, the creep properties, the compression and swelling properties in drained and undrained conditions and the undrained thermomechanical properties. Measurements have been made at different densities, clay/sand mixtures and pore water compositions. The influence of temperature, rate of strain and testing technique has also been considered. The investigation has led to a supply of basic data for the material models which will be used at performance calculations. The results have also increased the general understanding of the function of smectitic clay as buffer material. The microstructural behaviour has been considered at the validation of the different test results and the validity of the effective stress theory has been discussed. Comparisons with the properties of Ca-smectite have also been made. (orig.)
Dispersions of silica nanoparticles in ionic liquids investigated with advanced rheology
International Nuclear Information System (INIS)
The colloidal stabilities of dispersions of unmodified and surface-functionalized SiO2 nanoparticles in hydrophobic and hydrophilic imidazolium-based ionic liquids were studied with advanced rheology at three temperatures (25, 100, and 200 �C). The rheological behavior of the dispersions was strongly affected by the ionic liquids hydrophilicity, by the nanoparticles surface, by the concentration of the nanoparticles in the dispersion as well as by the temperature. The unmodified hydrophilic nanoparticles showed a better compatibility with the hydrophilic ionic liquid. The SiO2 surface functionalization with hydrophobic groups clearly improved the colloidal stability of the dispersions in the hydrophobic ionic liquid. The temperature increase was found to lead to a destabilization in all studied systems, especially at higher concentrations. The results of this study imply that ionic liquids with tailored properties could be used in absorbers directly after reactors for gas-phase synthesis of nanoparticles or/and as solvents for their further surface functionalization without agglomeration or aggregation.
Solid polymer electrolyte from phosphorylated chitosan
International Nuclear Information System (INIS)
Recently, the need of secondary battery application continues to increase. The secondary battery which using a liquid electrolyte was indicated had some weakness. A solid polymer electrolyte is an alternative electrolytes membrane which developed in order to replace the liquid electrolyte type. In the present study, the effect of phosphorylation on to polymer electrolyte membrane which synthesized from chitosan and lithium perchlorate salts was investigated. The effect of the component�s composition respectively on the properties of polymer electrolyte, was carried out by analyzed of it�s characterization such as functional groups, ion conductivity, and thermal properties. The mechanical properties i.e tensile resistance and the morphology structure of membrane surface were determined. The phosphorylation processing of polymer electrolyte membrane of chitosan and lithium perchlorate was conducted by immersing with phosphoric acid for 2 hours, and then irradiated on a microwave for 60 seconds. The degree of deacetylation of chitosan derived from shrimp shells was obtained around 75.4%. Relative molecular mass of chitosan was obtained by viscometry method is 796,792 g/mol. The ionic conductivity of chitosan membrane was increase from 6.33 � 10?6 S/cm up to 6.01 � 10?4 S/cm after adding by 15 % solution of lithium perchlorate. After phosphorylation, the ionic conductivity of phosphorylated lithium chitosan membrane was observed 1.37 � 10?3 S/cm, while the tensile resistance of 40.2 MPa with a better thermal resistance. On the strength of electrolyte membrane properties, this polymer electrolyte membrane was suggested had one potential used for polymer electrolyte in field of lithium battery applications
Solid polymer electrolyte from phosphorylated chitosan
Fauzi, Iqbal; Arcana, I. Made
Recently, the need of secondary battery application continues to increase. The secondary battery which using a liquid electrolyte was indicated had some weakness. A solid polymer electrolyte is an alternative electrolytes membrane which developed in order to replace the liquid electrolyte type. In the present study, the effect of phosphorylation on to polymer electrolyte membrane which synthesized from chitosan and lithium perchlorate salts was investigated. The effect of the component's composition respectively on the properties of polymer electrolyte, was carried out by analyzed of it's characterization such as functional groups, ion conductivity, and thermal properties. The mechanical properties i.e tensile resistance and the morphology structure of membrane surface were determined. The phosphorylation processing of polymer electrolyte membrane of chitosan and lithium perchlorate was conducted by immersing with phosphoric acid for 2 hours, and then irradiated on a microwave for 60 seconds. The degree of deacetylation of chitosan derived from shrimp shells was obtained around 75.4%. Relative molecular mass of chitosan was obtained by viscometry method is 796,792 g/mol. The ionic conductivity of chitosan membrane was increase from 6.33 � 10-6 S/cm up to 6.01 � 10-4 S/cm after adding by 15 % solution of lithium perchlorate. After phosphorylation, the ionic conductivity of phosphorylated lithium chitosan membrane was observed 1.37 � 10-3 S/cm, while the tensile resistance of 40.2 MPa with a better thermal resistance. On the strength of electrolyte membrane properties, this polymer electrolyte membrane was suggested had one potential used for polymer electrolyte in field of lithium battery applications.
Solid polymer electrolyte from phosphorylated chitosan
Energy Technology Data Exchange (ETDEWEB)
Fauzi, Iqbal, E-mail: email@example.com; Arcana, I Made, E-mail: email@example.com [Inorganic and Physical Chemistry Research Groups, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)
Recently, the need of secondary battery application continues to increase. The secondary battery which using a liquid electrolyte was indicated had some weakness. A solid polymer electrolyte is an alternative electrolytes membrane which developed in order to replace the liquid electrolyte type. In the present study, the effect of phosphorylation on to polymer electrolyte membrane which synthesized from chitosan and lithium perchlorate salts was investigated. The effect of the component�s composition respectively on the properties of polymer electrolyte, was carried out by analyzed of it�s characterization such as functional groups, ion conductivity, and thermal properties. The mechanical properties i.e tensile resistance and the morphology structure of membrane surface were determined. The phosphorylation processing of polymer electrolyte membrane of chitosan and lithium perchlorate was conducted by immersing with phosphoric acid for 2 hours, and then irradiated on a microwave for 60 seconds. The degree of deacetylation of chitosan derived from shrimp shells was obtained around 75.4%. Relative molecular mass of chitosan was obtained by viscometry method is 796,792 g/mol. The ionic conductivity of chitosan membrane was increase from 6.33 � 10{sup ?6} S/cm up to 6.01 � 10{sup ?4} S/cm after adding by 15 % solution of lithium perchlorate. After phosphorylation, the ionic conductivity of phosphorylated lithium chitosan membrane was observed 1.37 � 10{sup ?3} S/cm, while the tensile resistance of 40.2 MPa with a better thermal resistance. On the strength of electrolyte membrane properties, this polymer electrolyte membrane was suggested had one potential used for polymer electrolyte in field of lithium battery applications.
Electrochemical and rheological behaviour of a fluid zinc paste; Comportement electrochimique et rheologique d`une pate de zinc fluide
Energy Technology Data Exchange (ETDEWEB)
Sajot, N.
Zinc is a performing anodic material in numerous types of batteries. The anode of alkaline cells is typically a suspension of metallic powder in a gelled potassium hydroxide electrolyte, called zinc paste. We process such a homogeneous, fluid and stable paste, we study its physical electrochemical and rheological properties. Electrical power delivered during galvano-static electrolysis is about a few tens of mW.cm{sup -2} for anodic overvoltages inferior to 200 mV until the complete oxidation of the metal, 10 oxidation-reduction cycles are realised on paste samples of few mm width. In other respects, the product has a Bingham-type flow behavior, of critical shearing stress close to 200 Pa, and plastic viscosity about Pa.s, valid from 0,1 s{sup -1} shear rate. Zinc paste circulates in a slim rectangular section channel. Movement is ensured by a peristaltic pump placed on a cylindrical flexible tube. The paste transit between rectangular and circular sections is made through a profiled mechanical piece called a fish tail, without draft edge or roughness. An electrolytic separator and a current collector form the walls of the parallelopipedal channel, thus an electrolysis cell is framed. We record electrical and rheological characteristics of 2 oxidation-reduction cycles, during which the paste continues to flow and remains conductive. Established performances on the elementary cell allow to make up an air-zinc circulating paste battery for an electrical vehicle: the hydraulic recharge of a 100 l anodic paste tank is made in a few minutes, corresponding to a 300 km autonomy. (author) 87 refs.
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Full Text Available The microstructure and scaling of rheological properties of colloidal gels of bentonite investigated as a function of volume fraction and strength of interparticle interaction over a range of volume fractions, elastic modulus is well described with a scaling law functions of volume fractions, while the role of interparticle attractions can be accounted for by expressing these rheological properties as (?/?g-1n, where ?g captures the strength of particle interaction and n the microstructure.The scaling variable (?p/?pc-1, suggested in percolation theory to describe rheological behavior near percolation transition, acts to collapse G� data suggesting that along lines of constant (?/?g-1 these gels are rheologically identical.
Bentonites from Boa Vista, Brazil: physical, mineralogical and rheological properties
Scientific Electronic Library Online (English)
Luciana Viana, Amorim; Cynthia Morais, Gomes; Helio de Lucena, Lira; Kepler Borges, Fran�a; Heber Carlos, Ferreira.
Full Text Available The aim of this work is to characterize physically and mineralogically six samples of natural and industrialized bentonites from Para�ba, Brazil, and to study its rheological properties to be used as a components of water based drilling fluids. Also it is intended to compare the evolution of the min [...] eralogical composition and rheology of these clays after 40 years of exploitation. The natural bentonite clays were transformed into sodium bentonite by addition of concentrated Na2CO3 solution. The suspensions were prepared with 4.86% w/w to measure their rheological properties (apparent and plastic viscosities and water loss). The results showed that: i) the samples present typical mineralogical compositions of bentonites, but after four decades of exploitation, presents inferior quality and ii) among the clays samples, only one presented satisfactory rheological properties be used as a components of water based drilling fluids.
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Malyavskiy Nikolay Ivanovich / ????????? ??????? ????????
Full Text Available The author examine the features of the mechanisms of rheological anomaly involving reversing viscosity increase with increasing temperature in water solutions of four silicates with cations of different types. The crucial role of cation hydrolyzability for the origin of the anomaly was proved. It is shown that the rheological anomaly in lithium silicate solutions is caused by the phase decomposition of the system, not by the polymerization of silicate anions like in aminosilicate solutions / ??????? ??????????? ????????? ????????????? ????????, ?????????? ? ????????? ????????? ???????? ? ?????? ??????????? ? ?????? ????????? ??????? ????????? ? ????????? ????????? ?????. ???????????? ???????? ???? ??????????????? ??????? ? ????????????? ????????. ????????, ??? ????????????? ???????? ? ????????? ????????? ????? ??????? ??????? ??????????? ???????, ? ?? ?????????????? ?????????? ???????, ??? ? ????????? ??????????????
Rheological properties of whey proteins concentrate before and
Zoran Herceg; Vesna Lelas; Suzana Rimac
Hydrocolloids are long-chain polymers, used in food production at small quantities (from 0,05 to 5 %) to achieve appropriate rheological properties, prevent syneresis, increase the viscosity and stability of foodstuffs and for crystallization process control. The aim of this work was to investigate the influence of tribomechanical micronization of powdered whey protein concentrate on the rheological properties of whey proteins model systems as well as the influence of severalcarboxymethylcell...
Rheological and Electrical Transitions in Carbon Nanotube/Epoxy Suspensions
Allaoui, Aissa; El Bounia, Nour-eddine
The rheological and electrical properties of suspensions of carbon nanotubes in an uncured epoxy resin were investigated by means of shear rheology and impedance spectroscopy. It was found that above an onset CNT weight fraction (0.1 wt %), the steady viscosity increased with CNT loading and presented a shear thinning behaviour. The concentration dependence of viscosity changed from a power law to an exponential with increasing shear rate, indicating a loss of interaction be...
Rheological Properties of Oil in Water Emulsions and Particulate Suspensions
Chen, Shukun
This thesis aims at a better understanding of the rheologicalproperties of the important colloids in oil industry, i.e. suspensions, emulsions and waxes. The rheology of suspension system is a complex field influenced by a large range of variables. In this work, we mainly focused on the rheological properties of suspensions as a function of volume fraction of particles, particle size, surface properties, shear rate, and the nature of continuous mediums. The investigated suspensions behaved as...
Geodynamic inversion to quantify the rheological parameters of the lithosphere
Baumann, T.; Kaus, B.
The dynamics of the crust and lithosphere is to a large extent controlled by its effective viscosity. Typically, rheological parameters are estimated from laboratory experiments and extrapolated over ten orders of magnitude to geological conditions, which has significant uncertainties. In this study, we propose a method to constrain these parameters directly from geophysical observables. The method links lithosphere-dynamics models with geophysical observations (e.g. horizontal and vertical surface (GPS-) velocities, topography and gravity data). A Bayesian inversion strategy is employed to estimate probabilities of model parameters that affect the rheology of the lithosphere. As this requires many forward models (104 - 106), an efficient and parallel implementation is necessary, which we recently showed for 3D models with linear viscous rheologies (Baumann et al. 2014).Here, we examine how well this method is capable of resolving complex rheologies and address a few technical issues such as defining appropriate stopping criteria for models with a free surface. We use synthetic models of intra-oceanic subduction to demonstrate that the rheological parameters of the lithosphere can be recovered successfully even if rheologies are power-law viscous or plastic, provided that the temperature structure is known. A piece-wise linear lithospheric temperature parameterization as part of the inverse approach is shown to give reasonable results as well.Furthermore, we apply the method to cross-sections of the Himalaya where we consider different geological interpretations as end-member cases. For each end-member, we estimate the probabilities of their rheological structure and plasticity parameterisation and also obtain suitable temperature distributions. Our results indicate that the Indian mantle lithosphere has large effective viscosities whereas the Tibetan lower crust has small effective viscosities. This is consistent with many published modelling studies of the region. AcknowledgementsFunding was provided by ERC Grant agreement #258830ReferencesBaumann T.S., Kaus B.J.P., Popov A.A., 2014. Constraining effective rheology through parallel joint geodynamic inversion. Tectonophysics.
Rheology and texture of doughs: applications on wheat and corn
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Eduardo Rodr�guez Sandoval
Full Text Available A dough made of maylacceou materials shows a viscoelastic behavior, its macroestructural behavior depends on processing conditions, its constitutents and the interaction among them. Studies on dough rheology and texture are useful and important for applications that include ingredient specifications, quality control, product design and adaptation of new processing technologies. This work is a review of rheological and textural principles, testing methods and characteristics of wheat and com doughs.
Steady Rheological Properties of Rotating Biological Contactor (RBC) Sludge
Al-sameraiy, Mukheled; Banat, Fawzi; Abu-jdayil, Basim
The rheological characterization of sewage sludge at different steps of wastewater treatment is important since it allows predicting and estimating sludge behavior when submitted to almost all treatment and disposal operations. Rotating biological contactor (RBC) is being widely used for wastewater treatment, which is a biological treatment process following primary treatment. The rheological characterization of RBC sludge at different solid contents (TSS = 32.2 g/L�50.2 g/L) and temperatur...
Suspension of SiC Powders in Allyhydridopolycarbosilane (AHPCS): Control of Rheology
Hurwitz, Frances I.
Inert particulate fillers can be blended with preceramic polymers prior to infiltration of composite preforms to increase pyrolysis yield and decrease shrinkage, thus reducing the number of infiltration/ pyrolysis cycles required for densification. However, particulate filler loadings and concentration of added dispersants necessary to maintain low viscosity (< 0.50 N.s/sq m) slurries vary with the characteristics of the particular AHPCS polymer batch. These batch to batch variations occur with alterations in the synthesis process and method of allyl substitution, which in turn alter polymer structure and molecular weight distribution. A number of different polymer batches were characterized by NMR, GPC and thermal analysis, and the influence of polymer structure on rheology of filled systems determined. When the high molecular weight fraction increased to too great a level, suitably fluid slurries could no longer be attained.
Electrolytes near structured dielectric interfaces
Wu, Huanxin; Jing, Yufei; Solis, Francisco; Olvera de La Cruz, Monica; Luijten, Erik
The ion distribution in an electrolyte near a dielectric interface has important consequences for numerous applications. To date, most studies have focused on planar interfaces, where, e.g., simulations can take advantage of the image-charge method. However, for surfaces that display structure on the nanoscale, dielectric effects may be significantly different. Here, we investigate such interfaces via a combination of computer simulations and Poisson-Boltzmann theory. We demonstrate how, even for systems with piecewise uniform dielectric constant, surface structure affects the induced polarization charge as well as the ion distribution near the interface, in particular for asymmetric salts. We explore the role of ion concentration, dielectric mismatch and characteristic length scale of the surface structure.
Catalyzed electrolytic plutonium oxide dissolution
International Nuclear Information System (INIS)
Catalyzed electrolytic plutonium oxide dissolution (CEPOD) was first demonstrated at Pacific Northwest Laboratory (PNL) in early 1974 in work funded by the Exxon Corporation. The work, aimed at dissolution of Pu-containing residues remaining after the dissolution of spent mixed-oxide reactor fuels, was first publicly disclosed in 1981. The process dissolves PuO2 in an anolyte containing small (catalytic) amounts of elements that form kinetically fast, strongly oxidizing ions. These are continuously regenerated at the anode. Catalysts used, in their oxidized form, include Ag2+, Ce4+, Co3+, and AmO22+. This paper reviews the chemistry involved in CEPOD and the results of its application to the dissolution of the Pu content of a variety of PuO2-containing materials such as off-standard oxide, fuels dissolution residues, incinerator ash, contaminated soils, and other scraps or wastes. Results are presented for both laboratory-scale and plant-scale dissolves
Synthesis and characterization of partially fluorinated poly(acryl) ionomers for polymer electrolyte membrane fuel cells and ESR-spectroscopic investigation of the radically induced degradation of model compounds; Synthese und Charakterisierung teilfluorierter Poly(acryl)-Ionomere als Polymerelektrolytmembranen fuer Brennstoffzellen und ESR-spektroskopische Untersuchung der radikalinduzierten Degradation von Modellverbindungen
Energy Technology Data Exchange (ETDEWEB)
Schoenberger, Frank
In the first part of this work different strategies for the design of sulfonated partially fluorinated poly(aryl)s are developed and synthetically realized. The applied concept is that partially fluorinated poly(aryl)s are distinguished from the nonfluorinated ones by an enhanced acidity. Moreover they possess higher bond dissociation energies of both the C-F bonds and any adjacent C-H bonds which should be associated with a gain in radical stability and thus in chemical and thermal stability. In order to investigate the influence of the chemical structure of (partially fluorinated) monomeric building blocks, homo-polymers with different structural units (with aromatic C-F bonds, C(CF3)2-bridged and/or CF3-substituted phenylene rings) are synthesized by polycondensation and structurally characterized (elemental analysis, NMR spectroscopy, gel permeation chromatography). Established organic reactions, such as the Balz-Schiemann reaction, Suzuki reaction and Ullmann's biaryl synthesis, are applied for the synthesis of the specific monomers. After sulfonation of the homo-polymers (ionically crosslinked) membranes are prepared and characterized in terms of suitability as polymer electrolyte membrane in fuel cells (ion-exchange capacity, proton conductivity, thermal and chemical stability, water uptake, dimensional change). Both the chemical nature of the monomers and their constitution in the ionomer are important for the properties of the resulting membranes. Therefore microphase-separated multiblock-co-ionomers based on hydrophilic (sulfonated) and hydrophobic (partially fluorinated) telechelic macromonomers are prepared and characterized. Both the influence of the block length and the chemical nature of the used monomers on the membrane properties are comparatively investigated. On the basis of the findings gained in this part of the work, the advantages and disadvantages of partially fluorinated ionomer membranes are analyzed and discussed. The second part of this work deals with the EPR-spectroscopic investigation of radically induced degradation reactions of model compounds which represent structural units of poly(aryl) ionomers prepared in the first part of this work. These model compounds are exposed to hydroxyl and hydroperoxyl radicals in a flow cell, which are generated directly by photolysis of hydrogen peroxide in the cavity of an ESR spectrometer. By using this experimental setup different parameters (such as concentration of hydroxyl radicals, monomer concentration, flow rate, and pH value) are varied systematically and their influences in terms of the observed product formation of the aromatic model compounds with the hydroxyl radicals are estimated. Conclusions in terms of possible radical reactions of the poly(aryl) ionomer can be drawn from these investigations and information of avoidable structural features (e.g. type of the end groups of the ionomers) and avoidable conditions (e.g. inhomogeneities of pH values in the membrane) are obtained. (orig.)
Glue analysis and behavior in copper electrolyte
Blechta, V. K.; Wang, Z. Z.; Krueger, D. W.
Animal glue in combination with other chemicals is often used as a leveling agent in the copper electroplating industry. The control of the glue concentration in the electrolyte is critical to the quality of copper produced. A quantitative galvanostatic technique for glue analysis in copper electrolyte containing lignin sulfonate and Cl- was developed. The kinetics of glue hydrolysis in industrial electrolytes was studied and found to follow first-order reaction kinetics, with sulfuric acid acting as a catalyst. The dependence of the glue hydrolysis rate constant on temperature follows the Arrhenius equation. By adding fresh glue to the electrolyte, the glue activity first rises and then falls. This effect can be explained by the presence of long-chain molecules in the glue which are less active but hydrolyze into the more active medium-sized molecules. A mathematical model of this process shows good agreement with experimental data. The bulk of the electrolyte flow in the INCO commercial electrolytic plating cell bypasses the electrodes, probably across the bottom of the cell. The electrolyte circulation between electrodes is not very intense. A simple equation for the glue concentration calculation in the cell inlet and outlet, depending on the glue addition rate, was derived.
Review Of Rheology Models For Hanford Waste Blending
Energy Technology Data Exchange (ETDEWEB)
Koopman, D. C.; Stone, M.
The area of rheological property prediction was identified as a technology need in the Hanford Tank Waste - waste feed acceptance initiative area during a series of technical meetings among the national laboratories, Department of Energy-Office of River Protection, and Hanford site contractors. Meacham et al. delivered a technical report in June 2012, RPP-RPT-51652 ''One System Evaluation of Waste Transferred to the Waste Treatment Plant'' that included estimating of single shell tank waste Bingham plastic rheological model constants along with a discussion of the issues inherent in predicting the rheological properties of blended wastes. This report was selected as the basis for moving forward during the technical meetings. The report does not provide an equation for predicting rheological properties of blended waste slurries. The attached technical report gives an independent review of the provided Hanford rheological data, Hanford rheological models for single tank wastes, and Hanford rheology after blending provided in the Meacham report. The attached report also compares Hanford to SRS waste rheology and discusses some SRS rheological model equations for single tank wastes, as well as discussing SRS experience with the blending of waste sludges with aqueous material, other waste sludges, and frit slurries. Some observations of note: Savannah River Site (SRS) waste samples from slurried tanks typically have yield stress >1 Pa at 10 wt.% undissolved solids (UDS), while core samples largely have little or no yield stress at 10 wt.% UDS. This could be due to how the waste has been processed, stored, retrieved, and sampled or simply in the differences in the speciation of the wastes. The equations described in Meacham's report are not recommended for extrapolation to wt.% UDS beyond the available data for several reasons; weak technical basis, insufficient data, and large data scatter. When limited data are available, for example two to three points, the equations are not necessarily satisfactory (justified) for interpolations, due to the number of unknown variables equal the number of known data points, resulting in a coefficient of determination of one. SRS has had some success predicting the rheology of waste blends for similar waste types using rheological properties of the individual wastes and empirical blending viscosity equations. Both the Kendall-Monroe and Olney-Carlson equations were used. High accuracy was not obtained, but predictions were reasonable compared to measured flow curves. Blending SRS processed waste with frit slurry (much larger particles and the source of SRS glass formers) is a different sort of problem than that of two similar slurries of precipitated waste particles. A different approach to rheology prediction has had some success describing the incorporation of large frit particles into waste than the one used for blending two wastes. In this case, the Guth-Simha equation was used. If Hanford waste is found to have significant particles in the >100 ?m diameter range, then it might be necessary to handle those particles differently from broadly distributed waste particles that are primarily <30 ?m in diameter. The following are recommendations for the Hanford tank farms: Investigate the impact of large-scale mixing operations on yield stress for one or more Hanford tanks to see if Hanford waste rheological properties change to become more like SRS waste during both tank retrieval and tank qualification operations; Determine rheological properties of mobilized waste slurries by direct measurement rather than by prediction; Collect and characterize samples during the waste feed qualification process for each campaign; o From single source tanks that feed the qualification tanks; o Blends from the qualification tanks; Predictive rheological models must be used with caution, due to the lack of data to support such models and the utilization of the results that come from these models in making process decisions (e.g. the lack of actual operation experie
Review Of Rheology Models For Hanford Waste Blending
International Nuclear Information System (INIS)
The area of rheological property prediction was identified as a technology need in the Hanford Tank Waste - waste feed acceptance initiative area during a series of technical meetings among the national laboratories, Department of Energy-Office of River Protection, and Hanford site contractors. Meacham et al. delivered a technical report in June 2012, RPP-RPT-51652 ''One System Evaluation of Waste Transferred to the Waste Treatment Plant'' that included estimating of single shell tank waste Bingham plastic rheological model constants along with a discussion of the issues inherent in predicting the rheological properties of blended wastes. This report was selected as the basis for moving forward during the technical meetings. The report does not provide an equation for predicting rheological properties of blended waste slurries. The attached technical report gives an independent review of the provided Hanford rheological data, Hanford rheological models for single tank wastes, and Hanford rheology after blending provided in the Meacham report. The attached report also compares Hanford to SRS waste rheology and discusses some SRS rheological model equations for single tank wastes, as well as discussing SRS experience with the blending of waste sludges with aqueous material, other waste sludges, and frit slurries. Some observations of note: Savannah River Site (SRS) waste samples from slurried tanks typically have yield stress >1 Pa at 10 wt.% undissolved solids (UDS), while core samples largely have little or no yield stress at 10 wt.% UDS. This could be due to how the waste has been processed, stored, retrieved, and sampled or simply in the differences in the speciation of the wastes. The equations described in Meacham's report are not recommended for extrapolation to wt.% UDS beyond the available data for several reasons; weak technical basis, insufficient data, and large data scatter. When limited data are available, for example two to three points, the equations are not necessarily satisfactory (justified) for interpolations, due to the number of unknown variables equal the number of known data points, resulting in a coefficient of determination of one. SRS has had some success predicting the rheology of waste blends for similar waste types using rheological properties of the individual wastes and empirical blending viscosity equations. Both the Kendall-Monroe and Olney-Carlson equations were used. High accuracy was not obtained, but predictions were reasonable compared to measured flow curves. Blending SRS processed waste with frit slurry (much larger particles and the source of SRS glass formers) is a different sort of problem than that of two similar slurries of precipitated waste particles. A different approach to rheology prediction has had some success describing the incorporation of large frit particles into waste than the one used for blending two wastes. In this case, the Guth-Simha equation was used. If Hanford waste is found to have significant particles in the >100 ?m diameter range, then it might be necessary to handle those particles differently from broadly distributed waste particles that are primarily <30 ?m in diameter. The following are recommendations for the Hanford tank farms: Investigate the impact of large-scale mixing operations on yield stress for one or more Hanford tanks to see if Hanford waste rheological properties change to become more like SRS waste during both tank retrieval and tank qualification operations; Determine rheological properties of mobilized waste slurries by direct measurement rather than by prediction; Collect and characterize samples during the waste feed qualification process for each campaign; From single source tanks that feed the qualification tanks; Blends from the qualification tanks; Predictive rheological models must be used with caution, due to the lack of data to support such models and the utilization of the results that come from these models in making process decisions (e.g. the lack of actual operation experience). As experience is gained, the use of blen
Apparatus for the electrolytic production of metals
Sadoway, Donald R. (Belmont, MA)
Improved electrolytic cells for producing metals by the electrolytic reduction of a compound dissolved in a molten electrolyte are disclosed. In the improved cells, at least one electrode includes a protective layer comprising an oxide of the cell product metal formed upon an alloy of the cell product metal and a more noble metal. In the case of an aluminum reduction cell, the electrode can comprise an alloy of aluminum with copper, nickel, iron, or combinations thereof, upon which is formed an aluminum oxide protective layer.
Electrolytic orthoborate salts for lithium batteries
Angell, Charles Austen [Mesa, AZ; Xu, Wu [Tempe, AZ
Orthoborate salts suitable for use as electrolytes in lithium batteries and methods for making the electrolyte salts are provided. The electrolytic salts have one of the formulae (I). In this formula anionic orthoborate groups are capped with two bidentate chelating groups, Y1 and Y2. Certain preferred chelating groups are dibasic acid residues, most preferably oxalyl, malonyl and succinyl, disulfonic acid residues, sulfoacetic acid residues and halo-substituted alkylenes. The salts are soluble in non-aqueous solvents and polymeric gels and are useful components of lithium batteries in electrochemical devices.
Engineering design factors in flowing electrolyte bipolar batteries
Grimes, P.; Bellows, R.; Malachesky, P.
Various factors involved in the design optimization of flowing electrolyte battery systems are outlined. An example of a zinc bromide system is used, including a system description and a discussion of the electrolyte design, cell design, stack design, and electrolyte reservoir design. Examples of model output are given for electrolyte resistivity and utilization.
Heavy water recovery from combined electrolytic and non-electrolytic hydrogen streams
International Nuclear Information System (INIS)
A method is described for heavy water recovery as a valuable by-product from combined electrolytic and non-electrolytic hydrogen streams. The process is based on an important modification of the Combined Electrolysis and Catalytic Exchange-Heavy Water Process (CECE-HWP). The CECE-HWP is now in the small pilot plant stage of development. A highly dispersed platinum-carbon-Teflon catalyst on a ceramic carrier achieves efficient deuterium exchange between hydrogen gas and liquid water. The range of acceptable ratios of electrolytic to non-electrolytic hydrogen which may be chosen in the Modified CECE-HWP is discussed. Bench-scale results are presented which clearly demonstrate recovery of heavy water from both the electrolytic and non-electrolytic hydrogen streams. The potential application of the process to ammonia production is discussed and other possible applications are mentioned briefly. Advantages of adopting the process are outlined, including the important benefit of conserving fossil resources. (author)
Investigation of novel electrolyte systems for advanced metal/air batteries and fuel cells
Ye, Hui
It is a worldwide challenge to develop advanced green power sources for modern portable devices, transportation and stationary power generation. Metal/air batteries and fuel cells clearly stand out in view of their high specific energy, high energy efficiency and environment-friendliness. Advanced metal/air batteries based on metal ion conductors and proton exchange membrane (PEM) fuel cells operated at elevated temperatures (>120�C) can circumvent the limitations of current technologies and bring considerable advantages. The key is to develop suitable electrolytes to enable these new technologies. In this thesis research, investigation of novel electrolytes systems for advanced metal/air batteries and PEM fuel cells is conducted. Novel polymer gel electrolyte systems, [metal salt/ionic liquid/polymer] and [metal salt/liquid polyether/polymer] are prepared. Such systems contain no volatile solvents, conduct metal ions (Li+ or Zn 2+) with high ionic conductivity, possess wide electrochemical stability windows, and exhibit wide operating temperature ranges. They promise to enable non-aqueous, all-solid-state, thin-film Li/air batteries and Zn/air batteries. They are advantageous for application in other battery systems as well, such as rechargeable lithium and lithium ion batteries. In the case of proton exchange membranes, polymer gel electrolyte systems [acid/ionic liquid/polymer] are prepared. Especially, H3PO4/PMIH2PO 4/PBI is demonstrated as prospective proton exchange membranes for PEM fuel cells operating at elevated temperatures. Comprehensive electrochemical characterization, thermal analysis (TGA and DSC) and spectroscopy analysis (NMR and FTIR) are carried out to investigate these novel electrolyte systems and their ion transport mechanisms. The design and synthesis of novel ionic liquids and electrolyte systems based on them for advantageous application in various electrochemical power sources are highlighted in this work.
Directory of Open Access Journals (Sweden)
Monika Bozikova
Full Text Available This article deals with thermal properties of selected biooils Plahyd S biooil No1 and Plahyd N biooil No2 and rheologic properties of rapeseed oil. Plahyd S is a synthetic, rapidly biodegradable fluid which is based on sustainable raw materials. It is exceptionally suitable for applications in mobile and stationary hydraulic systems. Plahyd N is multigrade hydraulic oil based on rapeseed oil used in agricultural and construction machinery. For thermal parameters measurements was used Hot wire method. The experiment is based on measuring of the temperature rise vs. time evaluation of an electrically heated wire embedded in the tested material. The thermal conductivity is derived from the resulting change in temperature over a known time interval. Dependency of material resistance against the probe rotation was used at measurement of rheologic properties with instrument viscometer Anton Paar DV 3P. For two samples of biooils Plahyd N and Plahyd S were determined basic thermophysical parameters thermal conductivity, thermal diffusivity and volume specific heat. For each biooil samples were made two series of measurements. In the first series were measured thermal conductivity and thermal diffusivity at constant room temperature 20 C. Every thermophysical parameter was measured 10 times for each sample. The results were statistically processed. For biooil No1 thermal conductivity was 0.325 W*m 1 .K1 , it was higher value than we obtained for biooil No2 0.224 W*m 1 .K 1 . The similar results were obtained for thermal diffusivity of biooil No1 2.140.10 7 m 2 *s 1 and biooil No2 2.604.10 7 m 2* s 1 . For samples with constant temperature were calculated basic statistical characteristics as standard deviation for biooil No1 0.056 W*m 1*K 1 and biooil No2 0.054 W*m 1*K 1; probable error of the arithmetic average for biooil No 1 0.012 W*m 1*K 1 and biooil No 2 0.005 W*m 1*K 1, relative probable error in for biooil No1 3.69 per cent and biooil No2 2.23. The same statistical characteristics were calculated for thermal diffusivity. In the second series of measurements were measured relations of thermal conductivity and thermal diffusivity to the temperature in temperature range 20 29 C. From results was evident that all measured dependencies are nonlinear. For both thermophysical parameters were obtained polynomial functions of the second degree described by the polynomial coefficients. Type of function was selected according to statistical evaluation based on the coefficient of determination for every thermophysical parameter graphical dependency. In temperature dependency of rapeseed oil dynamic viscosity was used decreasing exponential function, which is in accordance with Arrhenius equation. The results obtained by the implementation of thermophysical and rheologic measurements on samples of biooils could be compared with the values presented in the literature.
Rheology and structure of thermoreversible hydrogels
Jiang, Jun
Highly concentrated solutions of non-ionic amphiphilic triblock copolymer poly(ethylene oxide)99-poly(propylene oxide)67-poly(ethylene oxide)99 (Pluronic F127) are widely used in numerous biomedical applications, such as drug delivery vehicles, and surfactants for emulsification of food and personal care products. The Pluronic copolymers are popular for these applications, since their gelation properties are thermoreversible and easily controlled by varying the concentration. They are liquid below room temperature and gel at body temperature. Hence they are great injectable biomaterials for tissue engineering and implantation. In this dissertation, thermal gelation and structure of high concentration triblock copolymer Pluronic F127-clay (Cloisite Na+ and Lucentite SWN) aqueous solutions were characterized by rheological measurements, differential scanning calorimetry (DSC) and small angle X-ray/neutron scattering. Small angle neutron scattering (SANS), under shear using a Couette cell in radial and tangential scattering geometry, was performed to examine the structural evolution of the polymeric micellar macro-lattice formed by concentrated aqueous solutions of triblock copolymer-Pluronic F127, as a function of the shear rate. The micellar gel showed a shear thinning, i.e., a reduction of the resistance to shear, by forming a layered stacking of two-dimensional hexagonally close packed (HCP) polymer micelles. A theoretical model was developed to calculate 2D SANS scattering patterns that can be compared with the experimental data. In order to improve the mechanical properties of the gel, while still maintaining the thermo-reversibility, we synthesized multiblock structures, where the F127 construct would be repeated several times. In this manner, physical interconnections between the micelles could occur as the multiblock copolymers formed interlocking loops and tails, thereby greatly increasing the mechanical strength of the gels. The rheological and structural properties of the gels were characterized as a function of temperature, composition and degree of polymerization. For F127 solutions just below their gel point, substitution of F127 with as little as 1% multiblock succeeded in forming a physical gel. Percolation theory was used to understand the modulus growth when multiblock was added to F127 solutions just below their gel point, assuming the multiblocks form bridges between adjacent micelles.
Highly Quantitative Electrochemical Characterization of Non-Aqueous Electrolytes & Solid Electrolyte Interphases
Energy Technology Data Exchange (ETDEWEB)
Sergiy V. Sazhin; Kevin L. Gering; Mason K. Harrup; Harry W. Rollins
The methods to measure solid electrolyte interphase (SEI) electrochemical properties and SEI formation capability of non-aqueous electrolyte solutions are not adequately addressed in the literature. And yet, there is a strong demand in new electrolyte generations that promote stabilized SEIs and have an influence to resolve safety, calendar life and other limitations of Li-ion batteries. To fill this gap, in situ electrochemical approach with new descriptive criteria for highly quantitative characterization of SEI and electrolytes is proposed. These criteria are: SEI formation capacity, SEI corrosion rate, SEI maintenance rate, and SEI kinetic stability. These criteria are associated with battery parameters like irreversible capacity, self-discharge, shelf-life, power, etc. Therefore, they are especially useful for electrolyte development and standard fast screening, allowing a skillful approach to narrow down the search for the best electrolyte. The characterization protocol also allows retrieving information on interfacial resistance for SEI layers and the electrochemical window of electrolytes, the other important metrics of characterization. The method validation was done on electrolyte blends containing phosphazenes, developed at Idaho National Laboratory, as 1.2M LiPF6 [80 % EC-MEC (2:8) (v/v) + 20% Phosphazene variety] (v/v), which were targeted for safer electrolyte variations.
Boron clusters as highly stable magnesium-battery electrolytes.
Carter, Tyler J; Mohtadi, Rana; Arthur, Timothy S; Mizuno, Fuminori; Zhang, Ruigang; Shirai, Soichi; Kampf, Jeff W
Boron clusters are proposed as a new concept for the design of magnesium-battery electrolytes that are magnesium-battery-compatible, highly stable, and noncorrosive. A novel carborane-based electrolyte incorporating an unprecedented magnesium-centered complex anion is reported and shown to perform well as a magnesium-battery electrolyte. This finding opens a new approach towards the design of electrolytes whose likelihood of meeting the challenging design targets for magnesium-battery electrolytes is very high. PMID:24519845
Electrolytic tiltmeters inside magnetic fields: Some observations
International Nuclear Information System (INIS)
We present observations of the electrolytic clinometers behaviour inside magnetic field environments introducing phenomenological expressions to account for the measured output voltage variations as functions of field gradients and field strengths
Fluctuation induced effects in confined electrolyte solutions
Brandes, T
We examine electrolyte systems confined between two parallel, grounded metal plates using a field-theoretic approach truncated at one-loop order. For symmetric electrolytes, the density distribution of the ions is non-uniform, with a maximum value at the center of the system. For asymmetric electrolytes, the system is no longer locally neutral, and there is a non-zero static electric potential. In addition, the surface of the metal plates becomes charged. When the plate separation becomes greater than the screening length, the charge distribution possesses two peaks with a local minimum at the center of the system. When the plates are immersed in a bulk electrolyte solution, an attractive fluctation induced force develops between them that is analogous to the Casimir force. Unlike the Casimir force, however, this attractive interaction has a finite limit in the zero separation limit and decays inversely with the separation at large separations.
Self-doped molecular composite battery electrolytes
Harrup, Mason K.; Wertsching, Alan K.; Stewart, Frederick F.
This invention is in solid polymer-based electrolytes for battery applications. It uses molecular composite technology, coupled with unique preparation techniques to render a self-doped, stabilized electrolyte material suitable for inclusion in both primary and secondary batteries. In particular, a salt is incorporated in a nano-composite material formed by the in situ catalyzed condensation of a ceramic precursor in the presence of a solvated polymer material, utilizing a condensation agent comprised of at least one cation amenable to SPE applications. As such, the counterion in the condensation agent used in the formation of the molecular composite is already present as the electrolyte matrix develops. This procedure effectively decouples the cation loading levels required for maximum ionic conductivity from electrolyte physical properties associated with condensation agent loading levels by utilizing the inverse relationship discovered between condensation agent loading and the time domain of the aging step.
Single-ion conducting polymer-silicate nanocomposite electrolytes for lithium battery applications
International Nuclear Information System (INIS)
Solid-state polymer-silicate nanocomposite electrolytes based on an amorphous polymer poly[(oxyethylene)8 methacrylate], POEM, and lithium montmorillonite clay were fabricated and characterized to investigate the feasibility of their use as 'salt-free' electrolytes in lithium polymer batteries. X-ray scattering and transmission electron microscopy studies indicate the formation of an intercalated morphology in the nanocomposites due to favorable interactions between the polymer matrix and the clay. The morphology of the nanocomposite is intricately linked to the amount of silicate in the system. At low clay contents, dynamic rheological testing verifies that silicate incorporation enhances the mechanical properties of POEM, while impedance spectroscopy shows an improvement in electrical properties. With clay content ?15 wt.%, mechanical properties are further improved but the formation of an apparent superlattice structure correlates with a loss in the electrical properties of the nanocomposite. The use of suitably modified clays in nanocomposites with high clay contents eliminates this superstructure formation, yielding materials with enhanced performance
Ionic Liquid Electrolytes for Photoelectrochemical Solar Cells
Gamstedt, Hel�ne
Potential electrolytes for dye-sensitized photoelectrochemical solar cells have been synthesized and their applicability has been investigated. Different experimental techniques were used in order to characterize the synthesized electrolytes, such as elemental analysis, electrospray ionisation/mass spectrometry, cyclic voltammetry, dynamic viscosity measurements, as well as impedance, Raman and NMR spectroscopy. Some crystal structures were characterized by using single crystal X-ray diffract...
Magnesium removal in the electrolytic zinc industry:
Booster, J. L.
Electrolytic zinc plants need to take measures to control the magnesium content in their process liquors, because the natural magnesium bleed does not balance the input from concentrates. Presently used methods are environmentally unfriendly (due to the production of large amounts of waste gypsum) or expensive. Therefore, an alternative process route is explored in which magnesium is removed from zinc electrolyte by selective precipitation of magnesium fluoride (sellaite). As standard applica...
Electrolyte Additives for Phosphoric Acid Fuel Cells
Gang, Xiao; Hjuler, H.A.; Olsen, C.A.; Berg, Rolf W.; Bjerrum, Niels
Electrochemical characteristics of a series of modified phosphoric acid electrolytes containing fluorinated car on compounds and silicone fluids as additives are presented. When used in phosphoric acid fuel cells, the modified electrolytes improve the performance due to the enhanced oxygen reduction rate. Among useful additives we found potassium perfluorohexanesulfonate (C6F13SO3K), potassium nonafluorobutanesulfonate (C4F9SO3K), perfluorotributylamine [(C4F9)3N], and polymethylsiloxanes [(-...
Rheological and fractal hydrodynamics of aerobic granules.
Tijani, H I; Abdullah, N; Yuzir, A; Ujang, Zaini
The structural and hydrodynamic features for granules were characterized using settling experiments, predefined mathematical simulations and ImageJ-particle analyses. This study describes the rheological characterization of these biologically immobilized aggregates under non-Newtonian flows. The second order dimensional analysis defined as D2=1.795 for native clusters and D2=1.099 for dewatered clusters and a characteristic three-dimensional fractal dimension of 2.46 depicts that these relatively porous and differentially permeable fractals had a structural configuration in close proximity with that described for a compact sphere formed via cluster-cluster aggregation. The three-dimensional fractal dimension calculated via settling-fractal correlation, U?l(D) to characterize immobilized granules validates the quantitative measurements used for describing its structural integrity and aggregate complexity. These results suggest that scaling relationships based on fractal geometry are vital for quantifying the effects of different laminar conditions on the aggregates' morphology and characteristics such as density, porosity, and projected surface area. PMID:25836036
Predictability of Complex Modulus Using Rheological Models
Directory of Open Access Journals (Sweden)
N.I.Md. Yusoff
Full Text Available The objective of this study was to investigate the advantages and disadvantages of several linear visco-elastic rheological models applied to the unmodified and polymer-modified bitumens. It was found that all the models studied can be used to predict the linear visco-elastic of unmodified bitumens, aged and unaged samples reasonably well. In contrary, this condition was not really applicable on polymer-modified bitumens particularly for the unaged samples. The measured and predicted data was assessed using the discrepancy ratio (Ri, Mean Normalized Error (MNE and Average Geometric Deviation (AGD goodness of fitting statistical analysis. From the study, the modified Sigmoidal and Generalized Logistic Sigmoidal models were observed to be the most outstanding models, followed by the Christensen Anderson and Marasteanu (CAM, Christensen and Anderson (CA and 2S2P1D (2 springs, 2 parabolic elements and 1 spring models. The presence of semi-crystalline waves and elastomeric structures in the mixtures render the breakdown of time temperature equivalency principle.
Rheological properties of cold recycled mixtures
Directory of Open Access Journals (Sweden)
J�n Gillinger
Full Text Available The paper presents some of the results of research focused on cold recycled mixtures properties. Within the study, eight mixtures with a different amount of reclaimed asphalt, bitumen emulsion and cement were evaluated. The results of static creep, complex modulus and fatigue conducted on trapezoidal specimens are discussed in the paper. The static creep modulus and the complex modulus were investigated at temperatures 27 �C, 11 �C and 0 �C. These temperatures represent temperatures of asphalt layer with a thickness in the range from 20 to 25 cm for summer, spring/ autumn and winter in Slovakia. In addition fatigue was investigated at the temperature of 27 �C. It was found that the binder combination plays an important role in rheological performance of cold recycled mixtures. However, at different contents of reclaimed asphalt, the effect of bitumen emulsion was different. This can be observable particularly when analyzing the results of the fatigue test. The mixtures with a higher amount of cement were better in terms of the fatigue life. The investigated mixtures in general were little sensitive to the change of loading frequency which simulates the traffic speed.
Influence of Fat Content on Chocolate Rheology
Gabriele, D.; Migliori, M.; Baldino, N.; de Cindio, B.
Molten chocolate is a suspension having properties strongly affected by particle characteristics including not only the dispersed particles but also the fat crystals formed during chocolate cooling and solidification. Even though chocolate rheology is extensively studied, mainly viscosity at high temperature was determined and no information on amount and type of fat crystals can be detected in these conditions. However chocolate texture and stability is strongly affected by the presence of specific crystals. In this work a different approach, based on creep test, was proposed to characterize chocolate samples at typical process temperatures (approximately 30 �C). The analysis of compliance, as time function, at short times enable to evaluate a material "elasticity" related to the solid-like behavior of the material and given by the differential area between the Newtonian and the experimental compliance. Moreover a specific time dependent elasticity was defined as the ratio between the differential area, in a time range, and total area. Chocolate samples having a different fat content were prepared and they were conditioned directly on rheometer plate by applying two different controlled cooling rate; therefore creep were performed by applying a low stress to ensure material linear behavior. Experimental data were analyzed by the proposed method and specific elasticity was related to single crystal properties. It was found that fat crystal amount and properties depend in different way on fat content and cooling rate; moreover creep proved to be able to detect even small differences among tested samples.
Micellar Electrolytes in Organic Electrochemical Transistors
Cicoira, Fabio; Giuseppe, Tarabella; Nanda, Gaurav; Iannotta, Salvatore; Santato, Clara
Organic electrochemical transistors (OECTs) are promising for applications in sensing and bioelectronics. OECTs consist of a conducting polymer film (transistor channel) in contact with an electrolyte. A gate electrode immersed in the electrolyte controls the doping/dedoping level of the conducting polymer. OECTs can be operated in aqueous electrolytes, making possible the implementation of organic electronic materials at the interface with biology. The inherent signal amplification of OECTs has the potential to yield sensors with low detection limits and high sensitivity. In this talk we will present recent studies on OECTs using ionic surfactants (such as hexadecyl-trimethyl-ammonium bromide) as electrolytes. As the conducting polymer we used PEDOT:PSS, i.e. (Poly,3-4 ethylenedioxythiopene) doped with Poly(styrene sulphonate). Interestingly, ionic surfactant electrolytes result in large transistor current modulation, especially beyond the critical micellar concentration (CMC). Since micelles play a primary role in biological processes and drug-delivery systems, the use for micellar electrolytes opens new exciting opportunities for the use of OECTs in bioelectronics.
Electrolytic recovery of reactor metal fuel
Miller, W.E.; Tomczuk, Z.
A new electrolytic process and apparatus are provided using sodium, cerium or a similar metal in alloy or within a sodium beta or beta[double prime]-alumina sodium ion conductor to electrolytically displace each of the spent fuel metals except for cesium and strontium on a selective basis from the electrolyte to an inert metal cathode. Each of the metals can be deposited separately. An electrolytic transfer of spent fuel into the electrolyte includes a sodium or cerium salt in the electrolyte with sodium or cerium alloy being deposited on the cathode during the transfer of the metals from the spent fuel. The cathode with the deposit of sodium or cerium alloy is then shunted to an anode and the reverse transfer is carried out on a selective basis with each metal being deposited separately at the cathode. The result is that the sodium or cerium needed for the process is regenerated in the first step and no additional source of these reactants is required. 2 figs.
Nanocomposite polymer electrolytes for lithium batteries
Croce, F.; Appetecchi, G. B.; Persi, L.; Scrosati, B.
Ionically conducting polymer membranes (polymer electrolytes) might enhance lithium-battery technology by replacing the liquid electrolyte currently in use and thereby enabling the fabrication of flexible, compact, laminated solid-state structures free from leaks and available in varied geometries. Polymer electrolytes explored for these purposes are commonly complexes of a lithium salt (LiX) with a high-molecular-weight polymer such as polyethylene oxide (PEO). But PEO tends to crystallize below 60�C, whereas fast ion transport is a characteristic of the amorphous phase. So the conductivity of PEO-LiX electrolytes reaches practically useful values (of about 10-4Scm-1) only at temperatures of 60-80�C. The most common approach for lowering the operational temperature has been to add liquid plasticizers, but this promotes deterioration of the electrolyte's mechanical properties and increases its reactivity towards the lithium metal anode. Here we show that nanometre-sized ceramic powders can perform as solid plasticizers for PEO, kinetically inhibiting crystallization on annealing from the amorphous state above 60�C. We demonstrate conductivities of around 10-4Scm-1 at 50�C and 10-5Scm-1 at 30�C in a PEO-LiClO4 mixture containing powders of TiO2 and Al2O3 with particle sizes of 5.8-13nm. Further optimization might lead to practical solid-state polymer electrolytes for lithium batteries.
Polymer electrolytes based on polyanionic lithium salts
International Nuclear Information System (INIS)
Highlights: �Polymer electrolytes composed of PEO and a polyanionic lithium salt were prepared. �The addition of BF3�OEt2 increases the ionic conductivities by one to two orders. �The structure of functional group of lithium salts affects electrolytes properties. -- Abstract: Polymer electrolytes composed of poly(ethylene oxide) and a polyanionic lithium salt are prepared, and electrochemical and thermal properties were investigated in the absence and presence of BF3�OEt2. The addition of BF3�OEt2 increases the ionic conductivities, and the lithium ion transference number of the polymer electrolyte for the PEO/poly(lithium acrylate) (PLA) and PEO/poly(lithium vinylsulfonate) (PLVS) system were higher than that of PEO/lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) system. However, ionic conductivities of the polymer electrolyte in the presence of BF3�OEt2 for the PEO/PLVS system were higher than that for the PEO/PLA system below 50 �C, due to the suppression of the crystallization of PEO. It was found that the structure of functional group in polyanionic lithium salts significantly affect electrochemical and thermal properties of polymer electrolytes
Preparation of intercalation compounds of carbon fibers through electrolysis using phosphoric acid electrolyte and their exfoliation
Toyoda, Masahiro; Yoshinaga, Aya; Amao, Yutaka; Takagi, Hideyuki; Soneda, Yasushi; Inagaki, Michio
Preparation of intercalation compounds using H3PO4 electrolyte solution in mesophase-pitch-based carbon fibers successfully carried out by electrolysis in less than 10 mol/dm3 of its electrolyte solution. Structural changes with preparation of intercalation compounds of carbon fibers were confirmed by a peak appeared around 2?=8� observed after electrolysis, which corresponds to an interlayer spacing of about 0.9 nm through XRD pattern (anticathode: Cu K?). This new peak was reasonably supposed to be due to the intercalation into interspacing of carbon layers. Suitable synthesis condition of the intercalation compounds was determined to be the concentration of electrolyte of 5 mol/dm3 at the electrolysis. It was also confirmed by morphology changes through SEM, that is carbon fibers, which treated low electrolyte concentration synthesized the intercalation compounds easily, and then it revealed markedly morphology changes such as fibrils. It could become exfoliation as well as them treated by other acid treatment through rapid heat-treatment. The formation of graphite oxide was suggested when the kind of intercalate was analyzed with elementary and TPD analysis.
Recent progress in the development and use of organic ionic plastic crystal electrolytes.
Pringle, Jennifer M
Significant progress has been made recently in the development of Organic Ionic Plastic Crystals (OIPCs), a unique family of solid state electrolytes with applications in electrochemical devices such as lithium batteries and dye-sensitised solar cells. The negligible volatility of OIPCs renders them more suitable than molecular species for long-term device use, while the high thermal and electrochemical stability of many OIPCs fulfils an essential requirement for solid state electrolytes for many device applications. However, the complex mechanisms of conduction through these materials, both in their pure state and in the presence of a small amount of a second component (such as lithium salts to enable their use in lithium batteries) are still not fully understood. At the same time, the range of anions and cations utilised in the synthesis of plastic crystal phases continues to increase. This perspective concentrates on recent research into both fundamental and device-oriented aspects of these materials. Important fundamental understanding of the physical properties and transport mechanisms of different OIPCs has been achieved through use of techniques including variable temperature solid-state NMR and crystallographic analysis, as well as detailed molecular dynamics simulations. In parallel, the applicability of these materials as electrolytes for dye-sensitised solar cells and lithium batteries is being more widely demonstrated. The possibility of using OIPCs as solid state electrolytes for fuel cells is also discussed. PMID:23184152
Molecular Interactions of the Difluoro(oxalato)borate Anion and Its Application for Lithium Ion Battery Electrolytes
Allen, Joshua Lee
Understanding the molecular interactions within electrolyte mixtures is essential for designing next generation electrolyte materials for high-voltage lithium ion (Li-ion) battery applications. Despite significant advancements in Li-ion battery electrode materials, which have theoretically enabled cell operation in excess of 5 V (vs. Li/Li+), the state-of-the-art electrolyte formulation has remained largely unchanged over two decades after its initial commercialization. To optimize the electrolyte properties, it is crucial to understand and relate the molecular-level interactions to the measured bulk properties. In the present study, these interactions have been explored through the use of the following techniques: phase diagrams (DSC analysis), X-ray single crystal structural determination, spectroscopic vibrational analysis (Raman) of the solvent and anion bands, and other techniques for determining electrolyte physical and electrochemical properties (density, viscosity and ionic conductivity). The primary focus of the present work is on the difluoro(oxalato)borate (DFOB--) anion and how the properties of this anion differ from other anions used in Li-ion battery electrolyte mixtures. The synthesis of highly pure LiDFOB is reported, along with the X-ray single crystal structural analysis of the neat salt and its dihydrate (LiDFOB�2H2O). The ion coordination behavior of the DFOB-- anion is compared with the structurally similar BF4 . and lithium bis(oxalato)borate (BOB --) anions. The decomposition mechanism and Raman vibrational band assignments for the LiDFOB salt are also compared with those for LiBF 4 and LiBOB. The carbonate-based solvents ethylene carbonate (EC) and propylene carbonate (PC) are of extraordinary importance due to their applications in state-of-the-art electrolytes. The Raman analysis of EC- and PC-based electrolyte mixtures to determine solvation numbers, without appropriate correction factors, is inherently flawed due to varying Raman scattering activities of the coordinated and uncoordinated solvent bands. In this study, correction factors are identified through joint quantum chemistry (QC) and experimental analysis techniques that enable the accurate analysis of EC and PC-based mixtures with lithium salts. From this analysis, the ionic association strength of the DFOB. anion was determined and compared to various lithium salt anions (PF6 --, TFSI--, BOB--, ClO 4 --, BF4--, CF 3SO3--, CF3CO2 --). Understanding the ionic association (Li+...anion) and ion solvation (Li+...solvent) interactions is crucial for an informed design process (i.e., electrolytes-on-demand) if these interactions can be directly linked to the physical and electrochemical properties of electrolyte mixtures. Thus, the solvation behavior of carbonate and lactone-based electrolytes with three lithium salts (LiBF4, LiDFOB and LiBOB) was investigated. Based upon the analysis of the solution structure of these mixtures, the electrolyte transport properties (viscosity and conductivity) were readily explainable. A direct link was therefore made between the solution structure of the electrolyte mixtures and the physicochemical properties they possess. LiDFOB has proven to be a highly versatile lithium salt, displaying many favorable battery properties including the formation of amorphous mixtures (even in mixtures with EC), relatively high ionic conductivity, and favorable electrode passivation layer properties when mixed with appropriate electrolyte solvents. Thus, alternative applications of the DFOB- anion have been explored, such as its use as an ionic liquid (IL) anion. N-Alkyl- N-methylpyrrolidinium difluoro(oxalato)borate (PY1RDFOB) ILs have been synthesized and characterized. These ILs are liquid at room temperature and have favorable Al corrosion properties, as well as a large electrochemical stability window. The present study provides a useful set of tools for scrutinizing a new electrolyte material; from the initial synthesis and purity evaluation, to examining ionic association and ion solvation interactions in electroly
Electrolytic production of uranous nitrate
International Nuclear Information System (INIS)
Efficient production of uranous nitrate is important in nuclear fuel reprocessing because U(IV) acts as a plutonium reductant in solvent extraction and can be coprecipitated with plutonium and/or throium as oxalates during fuel reprocessing. Experimental conditions are described for the efficient electrolytic production of uranous nitrate for use as a reductant in the SRP Purex process. The bench-scale, continuous-flow, electrolysis cell exhibits a current efficiency approaching 100% in combination with high conversion rates of U(VI) to U(IV) in simulated and actual SRP Purex solutions. High current efficiency is achieved with a voltage-controlled mercury-plated platinum electrode and the use of hydrazine as a nitrite scavenger. Conversion of U(VI) to U(IV) proceeds at 100% efficiency. Cathodic gas generation is minimal. The low rate of gas generation permits a long residence time within the cathode, a necessary condition for high conversions on a continuous basis. Design proposals are given for a plant-scale, continuous-flow unit to meet SRP production requirements. Results from the bench-scale tests indicate that an 8-kW unit can supply sufficient uranous nitrate reductant to meet the needs of the Purex process at SRP
77 FR 25406 - Consortium on �Concrete Rheology: Enabling Metrology (CREME)�: Membership Fee Update
...of Standards and Technology Consortium on ``Concrete Rheology: Enabling...of Standards and Technology, Commerce. ACTION...of Standards and Technology (NIST) published...Industry Consortium on Concrete Rheology:...
Model of ciliary clearance and the role of mucus rheology
Norton, Michael M.; Robinson, Risa J.; Weinstein, Steven J.
It has been observed that the transportability of mucus by cilial mats is dependent on the rheological properties of the mucus. Mucus is a non-Newtonian fluid that exhibits a plethora of phenomena such as stress relaxation, tensile stresses, shear thinning, and yielding behavior. These observations motivate the analysis in this paper that considers the first two attributes in order to construct a transport model. The model developed here assumes that the mucus is transported as a rigid body, the metachronal wave exhibits symplectic behavior, that the mucus is thin compared to the metachronal wavelength, and that the effects of individual cilia can be lumped together to impart an average strain to the mucus during contact. This strain invokes a stress in the mucus, whose non-Newtonian rheology creates tensile forces that persist into unsheared regions and allow the unsupported mucus to move as a rigid body whereas a Newtonian fluid would retrograde. This work focuses primarily on the Doi-Edwards model but results are generalized to the Jeffrey's fluid as well. The model predicts that there exists an optimal mucus rheology that maximizes the shear stress imparted to the mucus by the cilia for a given cilia motion. We propose that this is the rheology that the body strives for in order to minimize energy consumption. Predicted optimal rheologies are consistent with results from previous experimental studies when reasonable model parameters are chosen.
Determination of rheological properties using hybrid optimisation method
Directory of Open Access Journals (Sweden)
B. Foder
Full Text Available Purpose: of this paper is description of special software developed for identification of parameters values of rheological models used by ProCAST package for simulation of state of stress in the solidifying castings.Design/methodology/approach: The PyTensionTest uses a hybrid optimization algorithm. This algorithm includes the stochastic method which searches the starting point for direct search optimization method. The identification of parameters values is based on measurement results obtained within the confines of the material tests carried out using the testing machine.Findings: This paper presents the results of approximation of stress-strain relationship for two grades of steel using the elasto-plastic rheological model with power law hardening where its parameters are linearly dependent on temperature.Research limitations/implications: This paper presents the special software that allows user to define any rheological model.Practical implications: Application of obtained values of rheological parameters in the ProCAST software allows to determine stress and strain distribution in continuous castings. It can help to optimize important process parameters.Originality/value: Developed software can approximate the results of static tension tests using rheological model depended on material temperature. This software makes possible an approximation of several stressstrain curves simultaneously. Application of the hybrid optimization method allows to obtain very precise approximation due to determination of the global minimum of the goal function.
Rheological properties of crumb rubber modified bitumen containing antioxidant
International Nuclear Information System (INIS)
Rheology has become a useful tool in the characterization of the bitumen performance on the pavement. Visco-elastic properties of crumb rubber modified bitumen with antioxidants (CR30) were determined by the means of rheological measurement. This measurement led to a better knowledge of bitumen behavior that occurs when subjected to different thermal and mechanical conditions, as seen during road construction and services in the field. Dynamic Shear Rheometer (DSR) was used to characterize the rheology of the binders before and after oven aging. The binders were aged for 3 and 9 days. Results of a compatibility test showed that the addition of CR30 modified bitumen is compatible with the base bitumen. The results of unaged samples indicated that the addition of 1% CR30 and 5% CR30 modified binders caused an increase in G value as a result of the rheological changes. Results showed that aging has significant influence on bitumen rheology, by increasing complex modulus and decreasing phase angle. (author)
Model of ciliary clearance and the role of mucus rheology.
Norton, Michael M; Robinson, Risa J; Weinstein, Steven J
It has been observed that the transportability of mucus by cilial mats is dependent on the rheological properties of the mucus. Mucus is a non-Newtonian fluid that exhibits a plethora of phenomena such as stress relaxation, tensile stresses, shear thinning, and yielding behavior. These observations motivate the analysis in this paper that considers the first two attributes in order to construct a transport model. The model developed here assumes that the mucus is transported as a rigid body, the metachronal wave exhibits symplectic behavior, that the mucus is thin compared to the metachronal wavelength, and that the effects of individual cilia can be lumped together to impart an average strain to the mucus during contact. This strain invokes a stress in the mucus, whose non-Newtonian rheology creates tensile forces that persist into unsheared regions and allow the unsupported mucus to move as a rigid body whereas a Newtonian fluid would retrograde. This work focuses primarily on the Doi-Edwards model but results are generalized to the Jeffrey's and Maxwell fluids as well. The model predicts that there exists an optimal mucus rheology that maximizes the shear stress imparted to the mucus by the cilia for a given cilia motion. We propose that this is the rheology that the body strives for in order to minimize energy consumption. Predicted optimal rheologies are consistent with results from previous experimental studies when reasonable model parameters are chosen. PMID:21405727
Surface Morphology and Microstructure of Zinc Deposit From Imidazole with Zinc Chloride Low Temperature Molten Salt Electrolyte in The Presence of Aluminium Chloride
Directory of Open Access Journals (Sweden)
Shanmugasigamani Srinivasan, M. Selvam
Full Text Available Low temperature molten salts have variety of applications in organic synthesis, catalytic processing, batteries and electrode position due to their air and water stability. They have wide potential window for their applications in voltage and temperature and hence there is a possibility to deposit metals which could not be deposited from aqueous electrolytes. Our aim and scope of our research was to deposit zinc from low temperature molten salt electrolyte (LTMS containing zinc salt in the presence of aluminium chloride at different current densities and to qualify the nature of deposits. We could identify the effect of current density on the deposit at low temperature molten salt electrolyte by analysing the nature of deposits using different instrumental techniques. Compact, adherent, dense fine grained deposits of zinc with average grain size of 40-150 nm could be obtained from low temperature molten salt electrolyte. (LTMS
Electrochemical studies on polymer electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) membranes prepared by electrospinning and phase inversion-A comparative study
Energy Technology Data Exchange (ETDEWEB)
Raghavan, Prasanth; Zhao, Xiaohui; Manuel, James; Shin, Chorong; Heo, Min-Yeong [Department of Chemical and Biological Engineering and Engineering Research Institute, Gyeongsang National University, 900, Gajwa-dong, Jinju 660-701 (Korea, Republic of); Ahn, Jou-Hyeon, E-mail: email@example.com [Department of Chemical and Biological Engineering and Engineering Research Institute, Gyeongsang National University, 900, Gajwa-dong, Jinju 660-701 (Korea, Republic of); Ryu, Ho-Suk; Ahn, Hyo-Jun; Noh, Jung-Pil; Cho, Gyu-Bong [School of Nano and Advanced Materials Engineering and Engineering Research Institute, Gyeongsang National University, 900, Gajwa-dong, Jinju 660-701 (Korea, Republic of)
The synthesis, characterization and electrochemical properties of poly(vinylidene fluoride-co-hexafluoropropylene) {l_brace}P(VdF-co-HFP){r_brace} prepared by electrospinning and phase inversion methods are reported. The morphologies of the membranes were studied by field emission scanning electron microscope and atomic force microscope. Thermal properties of the membranes were evaluated by differential scanning calorimetry. The resultant porous membranes are good absorbents of liquid electrolytes and exhibit high electrolyte retention capacity. The polymer electrolytes were prepared by soaking the membranes in liquid electrolyte. The temperature dependent ionic conductivity and electrochemical properties were evaluated. Li/LiFePO{sub 4} cell with electrospun membrane delivers a discharge capacity of 145 mAh/g, which corresponds to 85% utilization of active material under the test conditions and shows lower capacity fade under continuous cycling.
Electrochemical studies on polymer electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) membranes prepared by electrospinning and phase inversion-A comparative study
International Nuclear Information System (INIS)
The synthesis, characterization and electrochemical properties of poly(vinylidene fluoride-co-hexafluoropropylene) {P(VdF-co-HFP)} prepared by electrospinning and phase inversion methods are reported. The morphologies of the membranes were studied by field emission scanning electron microscope and atomic force microscope. Thermal properties of the membranes were evaluated by differential scanning calorimetry. The resultant porous membranes are good absorbents of liquid electrolytes and exhibit high electrolyte retention capacity. The polymer electrolytes were prepared by soaking the membranes in liquid electrolyte. The temperature dependent ionic conductivity and electrochemical properties were evaluated. Li/LiFePO4 cell with electrospun membrane delivers a discharge capacity of 145 mAh/g, which corresponds to 85% utilization of active material under the test conditions and shows lower capacity fade under continuous cycling.
Controlled dissolution of polystyrene nanobeads: transition from liquid electrolyte to gel electrolyte.
Lee, Kun Seok; Jun, Yongseok; Park, Jong Hyeok
The widespread commercialization of dye-sensitized solar cells (DSSCs) remains limited because of the use of highly volatile liquid electrolytes. Recently, gel-type quasi-solid electrolytes containing a polymer additive or inorganic nanomaterial have shown promising results in terms of the cell efficiency. However, most gel electrolytes have serious obstacles for pore-filling because of their high viscosity. Herein, we report the first observation of the transition from a liquid to a gel electrolyte after filling the cell with the liquid electrolyte using the controlled dissolution of polystyrene nanobeads on the counter electrode, suggesting that the pore-filling problem can be diminished in quasi-solid state DSSCs. The time-resolved solidification allows for the preparation of the gel electrolyte without interfering with the cell performance. The optimal DSSC composed of the gel electrolyte exhibits almost the same power conversion efficiency as the liquid electrolyte based DSSC when measured using an AM1.5G solar simulator at 100 mW/cm(2) light illumination. Moreover, the long-term stability of the DSSC was greatly improved. PMID:22468779
Lithium carbon batteries with solid polymer electrolyte; Accumulateur lithium carbone a electrolyte solide polymere
Energy Technology Data Exchange (ETDEWEB)
Andrieu, X.; Boudin, F. [Alcatel Alsthom Recherche, 91 - Marcoussis (France)
The lithium carbon batteries studied in this paper use plasticized polymer electrolytes made with passive polymer matrix swollen by a liquid electrolyte with a high ionic conductivity (> 10{sup -3} S/cm at 25 deg. C). The polymers used to prepare the gels are polyacrylonitrile (PAN) and vinylidene poly-fluoride (PVdF). The electrochemical and physical properties of these materials are analyzed according to their composition. The behaviour of solid electrolytes with different materials of lithium ion insertion (graphite and LiNiO{sub 2}) are studied and compared to liquid electrolytes. The parameters taken into account are the reversible and irreversible capacities, the cycling performance and the admissible current densities. Finally, complete lithium ion batteries with gelled electrolytes were manufactured and tested. (J.S.) 2 refs.
Energy Technology Data Exchange (ETDEWEB)
Hansen, E.; Marzolf, A.; Hera, K.
The vane method has been shown to be an effective tool in measuring the yield stress of both settled and mixed slurries in laboratory bench scale conditions in supporting assessments of both actual and simulant waste slurries. The vane has also been used to characterize dry powders and granular solids, the effect of non-cohesive solids with interstitial fluids and used as a guide to determine if slip is present in the geometries typically used to perform rheological flow curve measurements. The vane has been extensively characterized for measuring the shear strength in soils in both field and laboratory studies. The objectives for this task are: Fabricate vane instrument; Bench top testing to further characterize the effect of cohesive, non-cohesive, and blends of cohesive/non-cohesive simple simulants; Data from measurement of homogenized and settled bed of Kaolin sludge and assessment of the technology. In this document, the assessment using bench scale measurements of non-cohesive materials (beads) and cohesive materials (kaolin) is discussed. The non-cohesive materials include various size beads and the vane was assessed for depth and deaeration (or packing) via tapping measurements. For the cohesive (or non-Newtonian) materials, flow curves and yield stress measurements are performed using the vane and this data is compared to the traditional concentric cylinder flow curve measurement. Finally, a large scale vane was designed, fabricated, and tested with the cohesive (or non-Newtonian) materials to determine how a larger vane performs in measuring the yield stress and flow curve of settled cohesive solids.
Ice rheology and tidal heating of Enceladus
Shoji, D.; Hussmann, H.; Kurita, K.; Sohl, F.
For the saturnian satellite Enceladus, the possible existence of a global ocean is a major issue. For the stability of an internal ocean, tidal heating is suggested as an effective heat source. However, assuming Maxwell rheology ice, it has been shown that a global scale ocean on Enceladus cannot be maintained (Roberts, J.F., Nimmo, F. [2008]. Icarus 194, 675-689). Here, we analyze tidal heating and the stability of a global ocean from the aspect of anelastic behavior. The Maxwell model is the most typical and widely used viscoelastic model. However, in the tidal frequency domain, energy is also dissipated by the anelastic response involving time-dependent or transient creep mechanisms, which is different from the viscoelastic response caused by steady-state creep. The Maxwell model cannot adequately address anelasticity, which has a large effect in the high viscosity range. Burgers and Andrade models are suggested as suitable models for the creep behavior of ice in the frequency domain. We calculate tidal heating in the ice layer and compare it with the radiated heat assuming both convection and conduction of the ice layer. Though anelastic behavior increases the heating rate, it is insufficient to maintain a global subsurface ocean if the ice layer is convecting, even though a wide parameter range is taken into account. One possibility to maintain a global ocean is that Enceladus� ice shell is conductive and its tidal response is similar to that of the Burgers body with comparatively small transient shear modulus and viscosity. If the surface ice with large viscosity is dissipative by anelastic response, the heat produced in the ice layer would supersede the cooling rate and a subsurface ocean could be maintained without freezing.
Rheology of water ices V and VI
International Nuclear Information System (INIS)
We have measured the mechanical strength (?) of pure water ices V and VI under steady state deformation conditions. Constant displacement rate compressional tests were conducted in a gas apparatus at confining pressures from 400 -7 -4 s-1. Most of the results fit to an empirical flow law of the form ampersand = A ?n exp (-E + PV)/RT, where the four material constants A, n, E, and I/* are (for ampersand in inverse seconds and P and ? in megapascals) 1023,0, 6.0, 136 kJ/mol, and 29 cm3/mol, respectively, for ice V; and 106,7, 4.5, 66 kJ/mol, and 11 cm3mol, respectively, for ice VI. Ice VI may weaken to a mechanism of higher E at T > 250 K. Ices V and VI are thus rheologically distinct but by coincidence have approximately the same strength under the conditions chosen for these experiments. To avoid misidentification, these tests are therfore accompanied by careful observations of the occurrences and characteristics of phase changes. One sample each of ice V and VI was quenched at pressure to metastably retain the high-pressure phase and the acquired deformation microstructures; X ray diffraction analysis of these samples confirmed the phase identification. Surface replicas of the deformed and quenched samples suggest that ice V probably deforms largely by dislocation creep, while ice VI dey by dislocation creep, while ice VI deforms by a more complicated process involving substantial grain size reduction through recrystallization. 25 refs., 10 figs., 3 tabs
Impact of Environmental Conditions (pH, Ionic Strength, And Electrolyte Type) On The Surface Charge And Aggregation Of Silver Nanoparticles Suspensions
The impact of capping agents and environmental conditions (pH, ionic strength, and background electrolytes) on surface charge and aggregation potential of silver nanoparticles (AgNPs) suspensions were investigated. Capping agents are chemicals used in the synthesis of nanopartic...
Relations between rheological and textural characteristics of yoghurt-modified mayonnaise.
Czech Academy of Sciences Publication Activity Database
�tern, Petr; Pokorn�, J.; Panovsk�, Z.
Hersonisos : European Society of Rheology, 2006. s. 177. [Annual European Rheology Conference AERC 2006 /3./. 27.04.2006-29.04.2006, Hersonisos, Crete] R&D Projects: GA AV ?R IAA2060404 Institutional research plan: CEZ:AV0Z20600510 Keywords : yoghurt -modified mayonnaise * rheology * viscoelasticity * sensory analysis * texture Subject RIV: BK - Fluid Dynamics
Determining the rheological properties of compressible powder materials in the high-temperature range
Buchatskii, L. M.; Stolin, A. M.
We discuss the behavior of powder materials in the case of high-temperature deformation. We have ascertained rheological variables and the possible types of rheological curves for the case of unilateral compression. We propose methods for the determination of the rheological properties, based on experimental data.
Introducing Students to Rheological Classification of Foods, Cosmetics, and Pharmaceutical Excipients Using Common Viscous Materials
Faustino, Ce�lia; Bettencourt, Ana F.; Alfaia, Anto�nio; Pinheiro, L�dia
Rheological measurements are very important tools for the characterization of the flow and deformation of a material, as well as for optimization of the rheological parameters. The application and acceptance of pharmaceutical formulations, cosmetics, and foodstuffs depends upon their rheological characteristics, such as texture, consistency, or�
Rheological behavior of magnetic powder mixtures for magnetic PIM
Kim, Sung Hun; Kim, See Jo; Park, Seong Jin; Mun, Jun Ho; Kang, Tae Gon; Park, Jang Min
Powder injection molding (PIM) is a promising manufacturing technology for the net-shape production of small, complex, and precise metal or ceramic components. In order to manufacture high quality magnets using PIM, the magneto-rheological (MR) properties of the PIM feedstock, i.e. magnetic powder-binder mixture, should be investigated experimentally and theoretically. The current research aims at comprehensive understanding of the rheological characteristics of the PIM feedstock. The feedstock used in the experiment consists of strontium ferrite powder and paraffin wax. Steady and oscillatory shear tests have been carried out using a plate-and-plate rheometer, under the influence of a uniform magnetic field applied externally. Rheological properties of the PIM feedstock have been measured and characterized for various conditions by changing the temperature, the powder fraction and the magnetic flux density.
Rheological behaviour of suspensions of bubbles in yield stress fluids
Duclou�, Lucie; Goyon, Julie; Chateau, Xavier; Ovarlez, Guillaume
The rheological properties of suspensions of bubbles in yield stress fluids are investigated through experiments on model systems made of monodisperse bubbles dispersed in concentrated emulsions. Thanks to this highly tunable system, the bubble size and the rheological properties of the suspending yield stress fluid are varied over a wide range. We show that the macroscopic response under shear of the suspensions depends on the gas volume fraction and the bubble stiffness in the suspending fluid. This relative stiffness can be quantified through capillary numbers comparing the capillary pressure to stress scales associated with the rheological properties of the suspending fluid. We demonstrate that those capillary numbers govern the decrease of the elastic and loss moduli, the absence of variation of the yield stress and the increase of the consistency with the gas volume fraction, for the investigated range of capillary numbers. Micro-mechanical estimates are consistent with the experimental data and provide...
Tidal dissipation in heterogeneous bodies: Maxwell vs Andrade rheology
Behounkova, M.; Cadek, O.
The tremendous volcanism on Jupiter's moon Io as well as the huge activity at the south pole of Saturn's moon Enceladus show that tidal dissipation is a very strong source of energy for some bodies in the Solar System. Outside the Solar System, tidal heating in short-period exoplanets may cause Io-like volcanism, large-scale melting and even thermal runaways [1-4]. Here we further develop the method to compute tidal heating in heterogeneous bodies [5]. Especially, we concentrate on the Andrade rheology implementation. We study the impact of the improved model on bodies with large lateral viscosity variation such as Enceladus and tidally locked exoEarth with a large surface temperature contrast due to uneven insolation [6]. We discuss the influence of empirical parameters describing the Andrade rheology and compare the tidal heating and tidal stress obtained for the Andrade rheology with frequently used Maxwell models for different forcing frequencies.
Rheological and microbiological study of flour treated by irradiation
International Nuclear Information System (INIS)
the aim this work is to study the effectiveness of radio treatment and its effect on the conservation of flour and their various parameters (physico-chemical and rheological). The flour has been treated with different doses (0, 0.75, 1.5 and 3 kGy), physico-chemical, rheological, microbiological and sensory analyses were made.The results show that the irradiation as a treatment for decontamination gave a highly effective. Indeed, a dose of 1.5 kGy allows a total destruction of yeasts and molds. Thus, from the point of view physico-chemical, increasing the dose of radiation causes a change in physical and chemical properties and rheological of flour. for the characteristics of bread, increasing the dose of radiation affects the quality of bread. (Author). 38 refs
Electrolytic hydrogen in beta titanium
International Nuclear Information System (INIS)
Permeation of electrolytic hydrogen through beta titanium foils with palladium coated surfaces was studied using Ti--11.5 Mo--6 Zr--4.5 Sn. Ion bombardment etching followed by thin film vapor deposition of palladium were used to produce oxide-free titanium specimens for electrochemical hydrogen permeation and embrittlement studies. A thin metallic foil is cathodically charged with hydrogen on one side while the other side is maintained at a sufficiently anodic potential so that all the diffusing hydrogen is oxidized and turned into an equivalent current. The current is analyzed to determine diffusivity and solubility of hydrogen. X-ray diffraction was also used to determine the effects of hydrogen on the lattice parameter. Permeation experiments conducted with basic cyanide solutions exhibited simple diffusion behavior. The diffusivity at 210C for hydrogen through the beta alloy was 5.60 (+-1.92) x 10-7 cm2/s. Anomalous permeation occurred with hydrogen chemical potentials in acidic and basic solutions without cyanide during the later stages of the approach to steady state in the charging. This behavior is consistent with the trapping model of hydrogen in metals of McNabb and Foster. Plastic deformation and spontaneous cracking at the wetted portion of the specimen were observed under extreme conditions during this anomalous behavior. Part of the deformation is found to be reversible. In the mandrel bend experiments on the embrittlemenndrel bend experiments on the embrittlement phenomenon, the transgranular cleavage mode of fracture occurred. Interstitially dissolved hydrogen expanded the bcc lattice of the beta titanium with accompanying diffraction line broadening. The lattice contracted upon removal of the hydrogen. The satisfactory performance of the beta alloy Ti--11.5 Mo--6 Zr--4.5 Sn, in moderate electrochemical environments results principally from the protective oxide film
Mantle Rheology and Plate Tectonics: Damage and Inheritance
Ricard, Y. R.; Bercovici, D.; Schubert, G.
The specific rheology of the lithosphere that allows the existence of plate tectonics on Earth is poorly understood. This rheology must explain why plate tectonics initiated on Earth but not on Venus, which has very similar size and gravity, but also how changes in plate motion can occur on time scales more rapid than that of the deeper convection (~100 myrs). We suggest that a key ingredient of this rheology is the coupling of the grain size evolution of the polycrystalline rocks that constitute the mantle, with the flow. We demonstrate this process using a grain evolution and damage mechanism (Bercovici and Ricard, 2012) with a composite rheology, which are compatible with field and laboratory observations. Our model predicts that the grain size is controlled by an dynamic equilibrium where deformation tends to reduce the grain sizes which otherwise would spontaneously increase. The presence of secondary phases is crucial as it eases the grain size reduction and inhibits their too fast recoveries. The resulting time-dependent rheology is non-linear, leads to localisation on time scales much shorter than those of the typical transit time of mantle convection but has also a long healing time. These characteristics of fast damage and long term memory is shown in simple models to spontaneously generate plates on a planet with Earth's parameters. For Venus hotter surface conditions, accumulation and inheritance of damage is negligible; hence only subduction zones survive and plate tectonics does not spread. This rheology also explains how subducting slabs can be rapidly detached when a buoyant crust is drawn into subduction and therefore how rapid plate changes can occur.
The rheological transition in plagioclase-bearing magmas
Picard, D.; Arbaret, L.; Pichavant, M.; Champallier, R.; Launeau, P.
Volcanological processes, such as melt segregation, ascent, and eruption, are directly dependent on the rheological behavior of magmatic suspensions. An increase of the crystal fraction of the suspension leads to the formation of a solid-particle network, which abruptly increases magma viscosity. The crystal fraction at which this rheological transition occurs depends on parameters such as the strain rate and the size, shape, and sorting of particles. To determine the influence of the crystal shape on the rheological transition, suspensions of plagioclase, a representative anisometric crystal, have been investigated at high temperatures and pressures. Synthetic suspensions with crystal fractions (?s) ranging from 0.38 to 0.75 were deformed both in compression and torsion in a Paterson apparatus at 300 MPa, 900�C and 800�C, and for strain rates between 1.0 � 10-5 and 1.0 � 10-3 s-1. All suspensions exhibit a non-Newtonian shear thinning rheological behavior. The experimental results, coupled with existing data and models at low crystal fractions (?s rheological domains to be identified, from steady-state flow to strain weakening, each characterized by a specific microstructure. In particular, a progressive evolution from a pervasive to a strain partitioning fabric is found when increasing the crystal fraction. Our results highlight the influence of both the strain rate and the shape of crystals on the rheological behavior of magmas. During crystallization, magmatic suspensions of anisometric minerals such as plagioclase would develop a solid-particle network earlier (?s ~ 0.3) than suspensions of isometric minerals (?s ~ 0.5). Our study shows that localization of strain early in the crystallization history of mushy zones in the magma chamber, near the conduit margins, and at the base of lava flows would facilitate the mobilization, the transfer, and the final emplacement at the surface of highly viscous, feldspar-rich magmas.
A dynamic rheological model for thin-film lubrication
International Nuclear Information System (INIS)
In this study, the effects of the non-Newtonian rheological properties of the lubricant in a thin-film lubrication regime between smooth surfaces were investigated. The thin-film lubrication regime typically appears in Stribeck curves with a clearly observable minimum coefficient of friction (COF) and a low-COF region, which is desired for its lower energy dissipation. A dynamic rheology of the lubricant from the hydrodynamic lubrication regime to the thin-film lubrication regime was proposed based on the convected Maxwell constitutive equation. This rheology model includes the increased relaxation time and the yield stress of the confined lubricant thin film, as well as their dependences on the lubricant film thickness. The Deborah number (De number) was adopted to describe the liquid-solid transition of the confined lubricant thin film under shearing. Then a series of Stribeck curves were calculated based on Tichy's extended lubrication equations with a perturbation of the De number. The results show that the minimum COF points in the Stribeck curve correspond to a critical De number of 1.0, indicating a liquid-to-solid transition of the confined lubricant film. Furthermore, the two proposed parameters in the dynamic rheological model, namely negative slipping length b (indicating the lubricant interfacial effect) and the characteristic relaxation time ?0, were found to determine the minimum COF and the width of the low-COF region, both of which were required to optimize the shape of the Stribeck curve. The developed dynamic rheological model interprets the correlation between the rheological and interfacial properties of lubricant and its lubrication behavior in the thin-film regime. (condensed matter: structural, mechanical, and thermal properties)
A dynamic rheological model for thin-film lubrication
Zhang, Xiang-Jun; Huang, Ying; Guo, Yan-Bao; Tian, Yu; Meng, Yong-Gang
In this study, the effects of the non-Newtonian rheological properties of the lubricant in a thin-film lubrication regime between smooth surfaces were investigated. The thin-film lubrication regime typically appears in Stribeck curves with a clearly observable minimum coefficient of friction (COF) and a low-COF region, which is desired for its lower energy dissipation. A dynamic rheology of the lubricant from the hydrodynamic lubrication regime to the thin-film lubrication regime was proposed based on the convected Maxwell constitutive equation. This rheology model includes the increased relaxation time and the yield stress of the confined lubricant thin film, as well as their dependences on the lubricant film thickness. The Deborah number (De number) was adopted to describe the liquid-solid transition of the confined lubricant thin film under shearing. Then a series of Stribeck curves were calculated based on Tichy's extended lubrication equations with a perturbation of the De number. The results show that the minimum COF points in the Stribeck curve correspond to a critical De number of 1.0, indicating a liquid-to-solid transition of the confined lubricant film. Furthermore, the two proposed parameters in the dynamic rheological model, namely negative slipping length b (indicating the lubricant interfacial effect) and the characteristic relaxation time ?0, were found to determine the minimum COF and the width of the low-COF region, both of which were required to optimize the shape of the Stribeck curve. The developed dynamic rheological model interprets the correlation between the rheological and interfacial properties of lubricant and its lubrication behavior in the thin-film regime.
Heavy-water extraction from non-electrolytic hydrogen streams
International Nuclear Information System (INIS)
Heavy water may be produced from non-electrolytic hydrogen streams using a combined electrolysis and catalytic exchange process. The method comprises contacting feed water in a catalyst column with hydrogen gas originating partly from a non-electrolytic hydrogen stream and partly from an electrolytic hydrogen stream, so as to enrich the feed water with the deuterium extracted from both the non-electrolytic and electrolytic hydrogen gas, and passing the deuterium water to an electrolyser wherein the electrolytic hydrogen gas is generated and then fed through the catalyst column. (L.L.)
Stabilizers: indispensable substances in dairy products of high rheology.
Tasneem, Madiha; Siddique, Farzana; Ahmad, Asif; Farooq, Umar
The functionality of stabilizers is apparent in many food applications including dairy products. The role of stabilizers like gelatin, pectins, alginates, carboxymethylcellulose, gums, ispghol, sago starch, and chitosan in the development of dairy products of high rheology, like yoghurt, ice cream, and flavored milk, is discussed in this review. Attention is also paid to comprehend on interactions among milk proteins, minerals, and other milk constituents with the reactive sites of stabilizers to get the desirable properties such as appearance, body and texture, mouthfeel, consistency. The role played by stabilizers in the control of syneresis and overrun problems in the high-rheology dairy products is also the topic of discussion. PMID:24499066
Rheological fluid motion in tube by metachronal wave of cilia
Maiti, S.; Pandey, S. K.
The purpose of this paper is a theoretical study of a non-linear problem of rheological fluid transport in an axisymmetric tube by cilium. However, an attempt has been made to explain the role of cilia motion on the transport of fluid through the ductus efferentes of the male reproductive tract. Ostwald-de Waele power law viscous fluid has been considered to represent the rheological fluid to analyze pumping by means of a sequence of beat of cilia from row to row of cilia in...
Rheological investigation of agricultural and food-industrial products
International Nuclear Information System (INIS)
We investigated the rheological properties of protein-containing food-industrial ingredient (milk protein concentrate powder and whole egg powder) as a function of absorbed gamma-dose (max. 20 kGy), using rotational viscosimeters. Our investigations form part of complex examination for comparing the above results with those of thermoluminescence, chemiluminescence and electron spin resonance methods applied for the study of irradiated foodstuffs. It was found that the rheological method was suitable for significant detection of irradiation in the case of protein-containing foodstuffs, even after a longer storage. (author). 8 refs, 5 figs, 1 tab
Electrical conductivity and rheology of carbon black composites under elongation
Star�, Zden?k
Electrical properties of conductive polymer composites are governed by filler particle structures which are formed in the material during the mixing. Therefore, knowledge of the behavior of conductive particle structures under defined conditions of deformation is necessary to produce materials with balanced electrical and rheological properties. Whereas the electrical conductivity evolution under shear can be nowadays studied even with the commercial rheometers, the investigations under elongation were not performed up to now. In this work simultaneous electrical and rheological measurements in elongation on polystyrene/carbon black composites are introduced. Such kind of experiment can help in understanding the relationships between processing conditions and properties of conductive polymer composites.
Rheological structure in Mars and its time evolution
Azuma, S.; Katayama, I.
Mars is one of the terrestrial planets which are composed of rock and metal such as the Earth. There is no water, no life, and no plate tectonics on Mars, suggesting that Mars and Earth followed different evolutionary paths. Rheological structure, which indicates the deformation behavior and the strength of planetary interior, plays an important role in the evolution of planets. The rheological behavior of planetary interiors is strongly sensitive to temperature, which may produce strong rheological layering. Rheological structure of Mars in past must be different from the current rheological structure. First, the evolutions of temperature profiles in Mars are inferred from the surface heat flow and the heat conduction equation. The surface heat flow of Mars every 1 billion years was calculated from present abundances of the radioactive isotopes (235U, 235U, 232Th, and 40K) and their half-lives (Hahn et al 2011). Based on the temperature profile, we calculate the rheological structure of Mars every 1 billion years using flow-law of plagioclase and olivine. Calculated rheological structure shows that the brittle-ductile transition of present Mars, which is transition of deformation behavior from brittle failure to viscous flow, is deeper as compared with that of past Mars, suggesting that current elastic thickness also becomes thicker than that of past Mars. Under water-saturated conditions, the rheological structure which simulates the northern lowlands shows the strength contrast between the crust and mantle, indicating that the decoupling might occur at the Moho from 4 Ga to present day. Under dry conditions, lithosphere of northern lowlands has no strength contrast at the Moho, implying that crust and mantle might be coupled from 3 Ga to present day. Viscosity contrast between the surface and planetary interior is key for the mantle convection style (Moresi and Solomatov 1995), and the calculated viscosity contrast at present Mars is ~10-5 (Pa), suggesting that Mars must be in the stagnant-lid convection regime. In contrast, the viscosity contrast of Mars from 4 Ga to 3 Ga seems to be ~104 (Pa), suggesting that Mars might have the potential to perform the plate tectonics such as Earth.
Rheological Study of Mutarotation of Fructose in Anhydrous State
Energy Technology Data Exchange (ETDEWEB)
Wang, Yangyang [ORNL; Wlodarczyk, Patryk [Institute ofNon-Ferrous Metals, Sowinskiego Gliwice, POLAND; Sokolov, Alexei P [ORNL; Paluch, Marian W [ORNL
Rheological measurement was employed to study the mutarotation of D-fructose in anhydrous state. By monitoring the evolution of shear viscosity with time, rate constants for mutarotation were estimated, and two different stages of this reaction were identified. One of the mutarotation stages is rapid and has a low activation energy, whereas the other is much slower and has a much higher activation energy. Possible conversions corresponding to these two phases are discussed. This work demonstrates that, in addition to the routine techniques such polarimetry and gas liquid chromatography, rheological measurement can be used as an alternative method to continuously monitor the mutarotation of sugars.
Rheology of Savannah River site tank 42 HLW radioactive sludge
Energy Technology Data Exchange (ETDEWEB)
Ha, B.C.
Knowledge of the rheology of the radioactive sludge slurries at the Savannah River Site is necessary in order to ensure that they can be retrieved from waste tanks and processed for final disposal. At Savannah River Site, Tank 42 sludge represents on of the first HLW radioactive sludges to be vitrified in the Defense Waste Processing Facility. The rheological properties of unwashed Tank 42 sludge slurries at various solids concentrations were measured remotely in the Shielded Cells at the Savannah River Technology Center using a modified Haake Rotovisco viscometer.
Rheology of Savannah River site tank 42 HLW radioactive sludge
International Nuclear Information System (INIS)
Knowledge of the rheology of the radioactive sludge slurries at the Savannah River Site is necessary in order to ensure that they can be retrieved from waste tanks and processed for final disposal. At Savannah River Site, Tank 42 sludge represents on of the first HLW radioactive sludges to be vitrified in the Defense Waste Processing Facility. The rheological properties of unwashed Tank 42 sludge slurries at various solids concentrations were measured remotely in the Shielded Cells at the Savannah River Technology Center using a modified Haake Rotovisco viscometer
Rheology of Nanoparticle Suspensions in Hydroxypropylcellulose (HPC) Solutions
Avil�s-Barreto, Sonia L.; Acevedo-Rull�n, Aldo
The effect of nanoparticle shape and concentration on the rheology of liquid crystalline solutions of hydroxypropyl cellulose (HPC) has been studied experimentally. Multiwalled carbon nanotubes (MWCNT) were dispersed by ultrasonification in HPC/M-cresol solutions, while commercial aqueous colloidal silica suspensions were mixed with HPC in water. The liquid crystalline phase behavior was identified by rheological measurements of the viscosity and optical microscopy of the solutions. Scaling arguments for the steady-state viscosity and the dynamic viscoelastic moduli will be presented. The effects of dispersion methods are also addressed.
Rheology of composite solid propellants during motor casting
Klager, K.; Rogers, C. J.; Smith, P. L.
Results of casting studies are reviewed so as to define the viscosity criteria insuring the fabrication of defect-free grains. The rheology of uncured propellants is analyzed showing that a realistic assessment of a propellant's flow properties must include measurement of viscosity as a function of shear stress and time after curing agent. Methods for measuring propellant viscosity are discussed, with particular attention given to the Haake-Rotovisko rotational viscometer. The effects of propellant compositional and processing variables on apparent viscosity are examined, as are results relating rheological behavior to grain defect formation during casting.
Solid Electrolyte for Advanced Lithium Batteries
Nazri, Gholam-Abbas; Mandal, Balaji P.; Nazri, Maryam; Naik, Vaman; Vashinava, Prem; Naik, Ratna
Lithium battery is a promising energy storage system due to its high energy density and high rate capability and its application ranges from micro to large scale megawatt batteries. The current technology is using liquid electrolyte that limits its application due to flammable nature of the electrolyte, particularly at high temperatures, and difficulty in fabrication and miniaturization of the device. We report a novel solid electrolyte with high lithium ion conductivity as a replacement for the current liquid electrolyte, particularly for electronic applications. The solid state lithium ion conductor is based on lithium germanium phosphorous sulfide compound. The compound is prepared by solid state reaction at 500 C. The crystallinity and phase purity of the sample is checked by XRD. We also measured ionic conductivity of the sample using both 4-probe and impedance techniques. High lithium ion conductivity at room temperature is observed. In this study we have investigated the dynamics of ion conduction, XRD, and Raman spectra of the super ion conductor. Electrochemical performance of the solid electrolyte in a lithium cell and its stability against high voltage cathodes and lithium anode will also be presented.
Morphology control in solid polymer electrolytes
Li, Christopher
Solid polymer electrolytes (SPEs) with high ionic conductivity are important for energy-related applications, such as solid state batteries and fuel cells. In this talk, I will discuss how nanoscale morphology affects the properties of SPEs. In the first part of the talk, I will show quantitatively that the effect of polymer crystallization on ion transport is twofold: structural (tortuosity) and dynamic (tethered chain confinement). We decouple these two effects by designing and fabricating a model polymer single crystal electrolyte system with controlled crystal structure, size, crystallinity, and orientation. Ion conduction is confined within the chain fold region and guided by the crystalline lamellae. We show that, at low ion content, due to the tortuosity effect, the in-plane conductivity is 2000 times greater than through-plane one. Contradictory to the general view, the dynamic effect is negligible at moderate ion contents. Our results suggest that semicrystalline polymer is a valid system for practical polymer electrolytes design. In the second part of the talk, I will discuss how to use holographic photopolymerization (HP) to fabricate long-range, defect-free, ordered SPEs with tunable ion conducting pathways. By incorporating polymer electrolytes into the carefully selected HP system, electrolyte layers/ion channels with length scales of a few tens of nanometers to micrometers can be formed. Confinement effects on ion transport will be reported.
Semi-active sliding mode control of vehicle suspension with magneto-rheological damper
Zhang, Hailong; Wang, Enrong; Zhang, Ning; Min, Fuhong; Subash, Rakheja; Su, Chunyi
The vehicle semi-active suspension with magneto-rheological damper(MRD) has been a hot topic since this decade, in which the robust control synthesis considering load variation is a challenging task. In this paper, a new semi-active controller based upon the inverse model and sliding mode control (SMC) strategies is proposed for the quarter-vehicle suspension with the magneto-rheological (MR) damper, wherein an ideal skyhook suspension is employed as the control reference model and the vehicle sprung mass is considered as an uncertain parameter. According to the asymptotical stability of SMC, the dynamic errors between the plant and reference systems are used to derive the control damping force acquired by the MR quarter-vehicle suspension system. The proposed modified Bouc-wen hysteretic force-velocity ( F- v) model and its inverse model of MR damper, as well as the proposed continuous modulation (CM) filtering algorithm without phase shift are employed to convert the control damping force into the direct drive current of the MR damper. Moreover, the proposed semi-active sliding mode controller (SSMC)-based MR quarter-vehicle suspension is systematically evaluated through comparing the time and frequency domain responses of the sprung and unsprung mass displacement accelerations, suspension travel and the tire dynamic force with those of the passive quarter-vehicle suspension, under three kinds of varied amplitude harmonic, rounded pulse and real-road measured random excitations. The evaluation results illustrate that the proposed SSMC can greatly suppress the vehicle suspension vibration due to uncertainty of the load, and thus improve the ride comfort and handling safety. The study establishes a solid theoretical foundation as the universal control scheme for the adaptive semi-active control of the MR full-vehicle suspension decoupled into four MR quarter-vehicle sub-suspension systems.
Directory of Open Access Journals (Sweden)
B Gabai
Full Text Available Abstract - Selective adsorbents have become frequently used in industrial processes. Recent studies have shown the possibility of using adsorption to separate copper refinery electrolyte contaminants, with better results than those obtained with conventional techniques. During copper electrorefinning, many impurities may be found as dissolved metals present in the anode slime which forms on the electrode surface, accumulated in the electrolyte or incorporated into the refined copper on the cathode by deposition. In this study, synthetic zeolites, chelating resins and activated carbons were tested as adsorbents to select the best adsorbent performance, as well as the best operating temperature for the process. The experimental method applied was the finite bath, which consists in bringing the adsorbent into contact with a finite volume of electrolyte while controlling the temperature. The concentration of metals in the liquid phase was continuously monitored by atomic absorption spectrophotometry (AAS
Micro-electrolytic iodination of polypeptide hormones
International Nuclear Information System (INIS)
This report describes a constant voltage microelectrolytic 125I-labelling procedure and applies it to the iodination of 5-50 ?g quantities of polypeptide hormones (synthetic salmon calcitonin, porcine glucagon, dog growth hormone, bovine growth hormone, bovine lutenizing hormone, bovine parathyroid hormone and bovine thyroid stimulating hormone). The electrolytic technique avoids exposure of the hormones to oxidizing agents which damage hormones and alter their biological and immunological activity. The labeled hormones showed no apparent damage by chromatoelectrophoresis or polyacrylamide gel filtration and all of the labelled hormones tested were either biologically or immunologically active. Finally, this simple, mild, and rapid micro-electrolytic iodination technique is highly reproducible, and rapid micro-electrolytic iodination technique is highly reproducible, yields a high degree of iodination and allows for the preparation of either high or low specific activity labeled hormone molecules. (author)
Optimization of the lithium-ion cell electrolyte composition through the use of the LiTDI salt
International Nuclear Information System (INIS)
Highlights: � LiTDI salt was tested in popular solvent mixtures as an electrolyte for Li-ion cells. � Beneficial broad conductivity plateaux with 0.3 mol kg?1 onset were found. � Viscosity, ionic associations and solvent-ions interactions are investigated. � Studied electrolytes have high lithium cation transference numbers (over 0.5). � Li+ conductivities of 0.3 mol kg?1 LiTDI are superior to industry standard mixtures. - Abstract: Optimization of electrolyte composition for future traction batteries is presented in this paper. Extensive systematic studies of electrochemical performance, material utility and subsequently cost are reported in order to obtain optimal combination. Lithium salt of TDI anion (4,5-dicyano-2-trifluoromethanoimidazole) is used due to its superior thermal stability (compared to other commercially available lithium salts), stability in case of moisture presence, electrochemical stability and possible material savings when used in electrolyte. Critical selection of solvent mixtures is made with respect to the price of components. Conductivity dependence of salt concentration is shown. For all studied systems the increased conductivity region is observed in the salt low and broad concentration range of 0.3 to 0.8 mol kg?1. The structural and rheological explanation of the mentioned feature is performed. Lithium cation transference numbers are measured for highly conductive samples and used as the secondary parameter in the optimization procedure. The highest values are recorded for the very low salt content: 0.31 mol kg?1 LiTDI in EC:DMC (1:2 weight ratio) (? = 5.09 mS cm?1, tLi+ = 0.622) and 0.4 mol kg?1 LiTDI in EC:DMC:DME (8:16:1 weight ratio) (? = 6.17 mS cm?1, tLi+ = 0.648) giving the opportunity to substantial material savings in batteries
Lithium-ion batteries having conformal solid electrolyte layers
Kim, Gi-Heon; Jung, Yoon Seok
Hybrid solid-liquid electrolyte lithium-ion battery devices are disclosed. Certain devices comprise anodes and cathodes conformally coated with an electron insulating and lithium ion conductive solid electrolyte layer.
Classical thermodynamics of non-electrolyte solutions
Van Ness, H C
Classical Thermodynamics of Non-Electrolyte Solutions covers the historical development of classical thermodynamics that concerns the properties of vapor and liquid solutions of non-electrolytes. Classical thermodynamics is a network of equations, developed through the formal logic of mathematics from a very few fundamental postulates and leading to a great variety of useful deductions. This book is composed of seven chapters and begins with discussions on the fundamentals of thermodynamics and the thermodynamic properties of fluids. The succeeding chapter presents the equations of state for
Impedance of metal-solid electrolyte interfaces
International Nuclear Information System (INIS)
Previous studies have shown that the impedance of solid state cells such as Pt/Na ?-alumina/Pt can be described by the function which depends on R, the bulk resistance of the electrolyte and two terms which represent the ac response of the metal-electrolyte interface, D and n. Deviation from ideal behavior (N6 Hz. The effect of surface roughness is illustrated. The impedances observed for the same Pt/Na ?-alumina/Pt cell at several temperatures are represented and discussed
Rheological Investigation on the Effect of Shear and Time Dependent Behavior of Waxy Crude Oil
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Japper-Jaafar A.
Full Text Available Rheological measurements are essential in transporting crude oil, especially for waxy crude oil. Several rheological measurements have been conducted to determine various rheological properties of waxy crude oil including the viscosity, yield strength, wax appearance temperature (WAT, wax disappearance temperature (WDT, storage modulus and loss modulus, amongst others, by using controlled stress rheometers. However, a procedure to determine the correct parameters for rheological measurements is still unavailable in the literature. The paper aims to investigate the effect of shear and time dependent behaviours of waxy crude oil during rheological measurements. It is expected that the preliminary work could lead toward a proper rheological measurement guideline for reliable rheological measurement of waxy crude oil.
Rheological study of chitosan acetate solutions containing chitin nanofibrils.
Czech Academy of Sciences Publication Activity Database
Mike�ov�, Jana; Ha�ek, Jind?ich; Tishchenko, Galina; Morganti, P.
Ro?. 112, 4 November (2014), s. 753-757. ISSN 0144-8617 Grant ostatn�: European Commission(XE) FP7-INFRASTRUCTURES n-CHITOPACK Project reference: 315233 Institutional support: RVO:61389013 Keywords : rheology * chitosan solutions * chitin nanofibrils Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.916, year: 2013
Rheological and Sensory Characteristics of Yoghurt-Modified Mayonnaise.
Czech Academy of Sciences Publication Activity Database
�tern, Petr; Pokorn�, J.; �ediv�, A.; Panovsk�, Z.
Ro?. 26, ?. 3 (2008), s. 190-198. ISSN 1212-1800 R&D Projects: GA AV ?R IAA2060404 Institutional research plan: CEZ:AV0Z20600510 Keywords : mayonnaise * rheology * sensory analysis * texture * yoghurt Subject RIV: BK - Fluid Dynamics Impact factor: 0.472, year: 2008
Rheological properties of whey proteins concentrate before and
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Zoran Herceg
Full Text Available Hydrocolloids are long-chain polymers, used in food production at small quantities (from 0,05 to 5 % to achieve appropriate rheological properties, prevent syneresis, increase the viscosity and stability of foodstuffs and for crystallization process control. The aim of this work was to investigate the influence of tribomechanical micronization of powdered whey protein concentrate on the rheological properties of whey proteins model systems as well as the influence of severalcarboxymethylcellulose hydrocolloids addition in such systems.Measurements were done using rotational viscosimeter, Brookfield DV-III at temperature 20 oC. The rheological parameters were determined by powerlaw model. The results of investigation have shown that all investigated systems are non-Newtonian. Depending on the pretreatment of whey proteins and the mass fractions of hydrocolloids they exhibited pseudoplastic or dilatant properties.Particle size analysis was performed using Fritsch � laser particle sizer �analysette 22�. The operation of tribomechanical micronization caused the decreasing of particle size and incrasing specific area of whey proteins. Tribomechanical treatment of whey proteins had significant influence on the rheological parameters and the type of flowing.
Rheological properties of nanofiltered Athabasca bitumen and Maya crude oil.
Czech Academy of Sciences Publication Activity Database
Hasan, M.D.A.; Fulem, Michal; Bazyleva, A.; Shaw, J.M.
Ro?. 23, - (2009), s. 5012-5021. ISSN 0887-0624 Institutional research plan: CEZ:AV0Z10100521 Keywords : viscosity * rheology * Athabasca bitumen * Maya crude oil * phase behavior * asphaltenes * nanofiltration Subject RIV: JJ - Other Materials Impact factor: 2.319, year: 2009
Bitumen and heavy oil rheological properties: reconciliation with viscosity measurements.
Czech Academy of Sciences Publication Activity Database
Bazyleva, A.B.; Hasan, M.D.A.; Fulem, Michal; Becerra, M.; Shaw, J.M.
Ro?. 55, ?. 3 (2010), s. 1389-1397. ISSN 0021-9568 Institutional research plan: CEZ:AV0Z10100521 Keywords : Athabasca bitumen * Maya crude oil * rheological properties * viscosity measurements Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.089, year: 2010
Continuum-mechanics-based rheological formulation for debris flow
Chen, Cheng-lung; Ling, Chi-Hai
This paper aims to assess the validity of the generalized viscoplastic fluid (GVF) model in the light of both the classical relative-viscosity versus concentration relation and the dimensionless stress versus shear-rate squared relations based on kinetic theory, thereby addressing how to evaluate the rheological parameters of the GVF model using Bagnold's data.
X-ray radiography for investigating rheological processes
International Nuclear Information System (INIS)
The applicability of X-ray radiography for investigating rheological processes during heated tool welding of polyethylene has been tested experimentally and is illustrated for 10 mm thick polyethylene pipes having diameter of 110 mm. Molybdenum powder has been used as contrast media
Rheological Characterization of Sludge Coming from a Wastewater Treatment Plant
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Daniel Novarino
Full Text Available Problem statement: The aim of this study was that of studying the rheology of sewage sludge using two different rheological test protocols taken from literature and comparing them in order to evaluate which useful information are given from every protocol. Approach: Two different protocols have been used taking particularly into account the problems connected to sludge heterogeneous composition and to the interaction between solid-solid and solid-water particles in order to completely understand the rheological behavior of this suspension; moreover, the consequences of particular effects connected to test geometry and conditions have been considered. Two fundamental parameters have been modified in the samples: The total solids content and the polyelectrolyte addition. Sludge with 3 and 5% of total solids have been investigated, with or without polyelectrolyte using also microscope analysis to understand the effect of polyelectrolyte on the sludge. Results: As expected, it was noticed that sludge viscosity grows up increasing the total solids content and with the presence of polyelectrolyte. The effect of polyelectrolyte is that of separating the liquid-phase from the solid-phase of the sludge giving a more space-heterogeneous suspension with higher viscosity and higher non-Newtonian behavior. Conclusion: This study proved that combining two different protocols of analysis can be useful to furnish important and complementary information on sludge rheology especially when some parameters change from sample to sample. Moreover, in order to have good and consistent results, it is necessary to use particular attention on samples pretreatments.
Rheology and wear of crosslinked UHMWPE for total joint replacements.
Czech Academy of Sciences Publication Activity Database
Hor�k, Zden?k; Mike�ov�, Jana; �louf, Miroslav; Fencl, J.
Madrid : Facultad de Medicina , Universidad Aut�noma de Madrid, 2007. s. 23. [UHMWPE International Meeting /3./ "Polyethylene in total joint replacement systems: Concerns and solutions". 14.09.2007-15.09.2007, Madrid] R&D Projects: GA M�k 2B06096 Institutional research plan: CEZ:AV0Z40500505 Keywords : UHMWPE * total joint replacements * rheology Subject RIV: CD - Macromolecular Chemistry
Rheological Properties of Liquid and Particle Stabilized Foam
�zarmut, A. �.; Steeb, H.
In Earth-Pressure-Balance (EPB) tunnelling the excavated ground is used as face support medium to prevent surface settlements. In general, the excavated ground (e.g. for cohesionless soils) does not exhibit suitable conditions to support the tunnelling face. This technical challenge can be solved by adding conditioning agents that are mainly foams. In order to physically understand the rheological properties of the (added) liquid foam and the foam-soil (foam-particle) mixture and to comprehend its influence on the soil, advanced rheological investigations are necessary. Therefore, rheological experiments such as flow curve tests have been performed to determine the effective yield stress. Since the morphology, i.e. the microstructure of the foam accounts for effective rheological properties, size, shape and distribution of the cells of the foam and particle-laden foam were characterized in detail applying imaging techniques. In order to perform the above mentioned experiments, polymer- stabilised shaving foam seems to be a good replacement of tunnelling foam and suitable for laboratory tests due to its time stability, characteristic length scales of the microstructure and accessibility. Glass beads (of different diameter and volume fractions, i.e. specific surface areas) are used to investigate the effective material behaviour of foam-particle mixtures. The experimental results are compared with yield stress models of modified Herschel-Bulkley- Papanastasiou type.
Influence of rheology on debris-flow simulation
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M. Arattano
Full Text Available Systems of partial differential equations that include the momentum and the mass conservation equations are commonly used for the simulation of debris flow initiation, propagation and deposition both in field and in laboratory research. The numerical solution of the partial differential equations can be very complicated and consequently many approximations that neglect some of their terms have been proposed in literature. Many numerical methods have been also developed to solve the equations. However we show in this paper that the choice of a reliable rheological model can be more important than the choice of the best approximation or the best numerical method to employ. A simulation of a debris flow event that occurred in 2004 in an experimental basin on the Italian Alps has been carried out to investigate this issue. The simulated results have been compared with the hydrographs recorded during the event. The rheological parameters that have been obtained through the calibration of the mathematical model have been also compared with the rheological parameters obtained through the calibration of previous events, occurred in the same basin. The simulation results show that the influence of the inertial terms of the Saint-Venant equation is much more negligible than the influence of the rheological parameters and the geometry. A methodology to quantify this influence has been proposed.
Dynamic hysteresis in the rheology of complex fluids
Puisto, Antti; Mohtaschemi, Mikael; Alava, Mikko J.; Illa, Xavier
Recently, rheological hysteresis has been studied systematically in a wide range of complex fluids combining global rheology and time-resolved velocimetry. In this paper we present an analysis of the roles of the three most fundamental mechanisms in simple-yield-stress fluids: structure dynamics, viscoelastic response, and spatial flow heterogeneities, i.e., time-dependent shear bands. Dynamical hysteresis simulations are done analogously to rheological ramp-up and -down experiments on a coupled model which incorporates viscoelasticity and time-dependent structure evolution. Based on experimental data, a coupling between hysteresis measured from the local velocity profiles and that measured from the global flow curve has been suggested. According to the present model, even if transient shear banding appears during the shear ramps, in typical narrow-gap devices, only a small part of the hysteretic response can be attributed to heterogeneous flow. This results in decoupling of the hysteresis measured from the local velocity profiles and the global flow curve, demonstrating that for an arbitrary time-dependent rheological response this proposed coupling can be very weak.
Rheological Behavior of an Epoxy Resin with Hollow Glass Microspheres
Costa, Cleber C.; Calado, Ver�nica; Tavares, Frederico W.
An investigation was carried out on the rheological behavior of a TET/DGEBA epoxy formulations with hollow glass microspheres using different types and different volume fractions of microspheres to manufacture composites. It was proposed an equation to describe viscosity as a function of microsphere volume fracion. The fit to the experimental data was excellent.
Rheological properties of chitosan solutions filled with chitin nanofibrils.
Czech Academy of Sciences Publication Activity Database
Mike�ov�, Jana; Tishchenko, Galina; Morganti, P.
Pisa : University of Pisa, Department of Civil and Industrial Engineering , 2013, s. 44-45. [Workshop Green Chemistry and Nanotechnologies in Polymer Chemistry /4./. Pisa (IT), 04.09.2013-06.09.2013] Grant ostatn�: European Commission(XE) FP7-INFRASTRUCTURES n-CHITOPACK Project reference: 315233 Institutional support: RVO:61389013 Keywords : chitosan solution * chitin nanofibrils * rheology Subject RIV: CD - Macromolecular Chemistry
Volcanism as a new constraint on the rheology of continents
Tait, S.; Dev�s, M.; King, G. C.; Grandin, R.; Tapponnier, P.
Our knowledge of lithospheric rheology comes mostly from laboratory data using small-scale samples that are extrapolated to crustal and lithospheric scales, which requires careful analysis of the differences in boundary conditions. In the search for constraints on large-scale continental rheology, one useful observation has been neglected. That is the occurrence of volcanism genetically related to faulting activity, which can be used to obtain information about the rheology of the continents. The volcanism can be explained by a �Process zone heating� mechanism that occurs at fault system complexities. The rate of heating directly depends on the rheology, and we explore which conditions produce sufficient heat to melt independently the crust and the mantle of the continental lithosphere as required by the observations. By comparing the source depth given by modelling with the geochemical and petrological features of the volcanic products, we are able to discuss the strength profile required for the genesis of the magmas. A shift appears between the power flow law parameters obtained in the laboratory and the ones that are required for melting to occur. We describe and model here instances of volcanism along the North Anatolian Fault, Turkey, but the scope can be broadened to other cases.
Continuum modeling of secondary rheology in dense granular materials.
Henann, David L; Kamrin, Ken
Recent dense granular flow experiments have shown that shear deformation in one region of a granular medium fluidizes its entirety, including regions far from the sheared zone, effectively erasing the yield condition everywhere. This enables slow creep deformation to occur when an external force is applied to a probe in the nominally static regions of the material. The apparent change in rheology induced by far-away motion is termed the "secondary rheology," and a theoretical rationalization of this phenomenon is needed. Recently, a new nonlocal granular rheology was successfully used to predict steady granular flow fields, including grain-size-dependent shear-band widths in a wide variety of flow configurations. We show that the nonlocal fluidity model is also capable of capturing secondary rheology. Specifically, we explore creep of a circular intruder in a two-dimensional annular Couette cell and show that the model captures all salient features observed in experiments, including both the rate-independent nature of creep for sufficiently slow driving rates and the faster-than-linear increase in the creep speed with the force applied to the intruder. PMID:25379938
Rheological characterization of reactive extrusion process based polypropylenes.
Czech Academy of Sciences Publication Activity Database
Zatloukal, M.; Pivokonsk�, Radek; Filip, Petr; Tzoganakis, C.
Salerno : Polymer Technology Group, 2008, S07-1050. ISBN 88-7897-025-5. [ PPS -24: The Polymer Processing Society. Salerno (IT), 15.06.2008-19.06.2008] R&D Projects: GA AV ?R IAA200600703 Institutional research plan: CEZ:AV0Z20600510 Keywords : Branched PP * Extensional rheology * constitutive equations Subject RIV: BK - Fluid Dynamics
Integrated System for Design and Analysis of Separation Processes with Electrolyte Systems
DEFF Research Database (Denmark)
Takano, Kiyoteru; Gani, Rafiqul
A thermodynamic insights based algorithm for integrated design and analysis of crystallization processes with electrolyte systems is presented. This algorithm consists of a thermodynamic calculation part, a process design/analysis part and a process simulation part, which are integrated through a calculation engine. The main feature of the algorithm is the use of thermodynamic insights, not only to identify and generate the feasible process alternatives, but also to obtain good initial estimates for the process simulation part, and for visualization of process synthesis/design. The main steps of the integrated system are illustrated through two case studies where one represents an industrial crystallization process.
Rheology of crumb-rubber modified asphalt binders and mixes
Sheth, Vikas Rameshchandra
Laboratory test procedures are presented to determine the rheological properties of crumb rubber modified asphalt (CRMA) binders and mixes. These tests provide simple, fast, and cost-effective alternatives to evaluate the performance (rutting and cracking potential) of binders and mixes used for pavement construction. Viscoelastic properties of CRMA binders are measured using dynamic shear analysis. Master curves were generated using the principle of time-temperature superposition to evaluate the effects of aging, rubber concentration, and curing conditions on the rheology of the modified binder. Results indicate that the rheology of CRMA binders can be divided into three regions of viscoelasticity: glassy region at high frequencies, transition/viscoelastic region at intermediate frequencies, and viscous region at low frequencies. Modification of the asphalt by addition of rubber leads to an improvement in both the high and low temperature properties, as reflected by changes in Gsp' and Gsp{''}, which causes the binder to have a greater resistance to specific pavement failure mechanisms. Both transient and dynamic properties of CRMA mixes were measured in the laboratory using the creep and recovery, direct tension, and frequency sweep tests. Rheological properties of the mix generated from the test data were compared to those of the binder to evaluate the effect of aging, rubber concentration, and curing conditions on mix performance. Several rheological parameters have been identified to characterize the rutting and cracking potential of mixes. A power law equation was found to give good correlations between several mix rheological parameters. Analysis of binder and mix failure energies show that work of cohesion of the binder is negligible compared to the failure energies. A unique relationship between Paris law material parameters has been confirmed. It is also shown that mix failure properties bear a one-to-one correlation with binder failure properties. Based on the results of this work, it is concluded that modification of asphalt by rubber produces a rheologically superior binder. This modified binder can be successfully used to fabricate laboratory mixes that exhibit better resistance to several failure mechanisms. CRMA binders should therefore be seriously considered as a cost-effective alternative for pavement construction.
Energy Technology Data Exchange (ETDEWEB)
Harlan U. Anderson; Wayne Huebner; Igor Kosacki
This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and testing of Planar Single Cells. In this portion of study we have focused on producing YSZ films on porous LSM substrates. When using the polymer precursor there are a number of obstacles to overcome in order to form dense electrolyte layers on porous substrates (cathode or anode). Probably the most difficult problems are: (1) Extreme penetration of the polymer into the substrate must be prevented. (2) Shrinkage cracking must be avoided. (3) Film thickness in the 1 to 5{micro}m range must be achieved. We have demonstrated that cracking due to shrinkage involved during the elimination of solvents and organic matter and densification of the remaining oxide is not a problem as long as the resulting oxide film is < {approx} 0.15 {micro}m in thickness. We have also shown that we can make thicker films by making multiple depositions if the substrate is smooth (roughness {le} 0.1 {micro}m) and contains no surface pores > 0.2 {micro}m. The penetration of the polymer into the porous substrate can be minimized by increasing the viscosity of the polymer and reducing the largest pore at the surface of the substrate to {le} 0.2 {micro}m. We have shown that this can be done, but we have also shown that it is difficult to make dense films that are defect free with areas > 1 cm{sup 2}. This is because of the roughness of the substrate and the difficulty in making a substrate which does not have surface voids > 0.2 {micro}m. Thus the process works well for dense, smooth substrates for films < 1 {micro}m thick, but is difficult to apply to rough, porous surfaces and to make film thickness > 1 {micro}m. As a result of these problems, we have been addressing the issue of how to make dense films in the thickness range of 1 to 5 {micro}m on sintered porous substrates without introducing cracks and holes due to shrinkage and surface voids? These endeavors have lead us to a solution which we think is quite unique and should allow us to obtain flaw free dense films of thickness in the 0.5 to 5 {micro}m range at processing temperatures {le} 900{sup o}. The process involves the deposition of a slurry of nanocrystalline YSZ onto a presintered porous LSM substrate. The key element in the deposition is that the slurry contains sufficient YSZ polymer precursor to allow adhesion of the YSZ particles to each other and the surface after annealing at about 600 C. This allows the formation of a porous film of 0.5 to 5 {micro}m thick which adheres to the surface. After formation of this film, YSZ polymer precursor is allowed to impregnate the porous surface layer (capillary forces tend to confine the polymer solution in the nanoporous layer). After several impregnation/heat treatment cycles, a dense film results. Within the next few months, this process should be developed to the point that single cell measurements can be made on 0.5 to 5 {micro}m films on a LSM substrate. This type of processing allows the formation of essentially flaw free films over areas > 1 cm{sup 2}.
Preliminary Evaluations of Polymer-based Lithium Battery Electrolytes Under Development for the Polymer Electrolyte Rechargeable Systems Program
Manzo, Michelle A.; Bennett, William R.
A component screening facility has been established at The NASA Glenn Research Center (GRC) to evaluate candidate materials for next generation, lithium-based, polymer electrolyte batteries for aerospace applications. Procedures have been implemented to provide standardized measurements of critical electrolyte properties. These include ionic conductivity, electronic resistivity, electrochemical stability window, cation transference number, salt diffusion coefficient and lithium plating efficiency. Preliminary results for poly(ethy1ene oxide)-based polymer electrolyte and commercial liquid electrolyte are presented.
Stable emulsions with thermally responsive microstructure and rheology using poly(ethylene oxide) star polymers as emulsifiers.
Saigal, Trishna; Yoshikawa, Alex; Kloss, Dennis; Kato, Masanari; Golas, Patricia Lynn; Matyjaszewski, Krzysztof; Tilton, Robert D
Poly(ethylene oxide) star polymers (PEO stars) were prepared by atom transfer radical polymerization of 2000 molecular weight PEO methacrylate macromonomer with divinylbenzene as a crosslinking co-monomer. With an average of 460 arms per star, these PEO stars had a 12 nm radius of gyration that is consistent with a dense polymer core surrounded by an extended PEO corona. The PEO stars were extremely efficient emulsifiers, stabilizing cyclohexane-in-water or xylene-in-water emulsions against coalescence for several months at aqueous phase concentrations as low as 0.008 wt% or 0.01 wt%, respectively. Consistent with their emulsifying performance, PEO star adsorption decreased interfacial tension by approximately 22 mN/m and imparted significant dilatational elasticity to the xylene/water interface. PEO stars were thermally responsive, displaying a cloud point upon heating in water that was tuned by addition of kosmotropic electrolytes, and they in turn produced xylene-in-water emulsions that were thermally responsive in terms of the dispersion state of the emulsion droplets and the emulsion rheology. Emulsions prepared at room temperature mainly had non-flocculated droplets. Heating such an emulsion above the cloud point temperature triggered droplet flocculation, but not coalescence, that in turn was associated with increased viscous and elastic moduli of the emulsion measured after cooling back to room temperature. Emulsions that initially were homogenized above the cloud point temperature and then cooled showed neither droplet flocculation nor rheological thickening relative to emulsions that were prepared and held at room temperature. A mechanism based on the bridging behavior of PEO stars adsorbed at the droplet/water interface is postulated to explain this thermal response of the emulsion microstructure. PMID:23266031
Conductivity studies on solid polymer electrolytes
International Nuclear Information System (INIS)
This thematic lecture addresses electrochemical conductivity techniques for the study of solid polymer electrolytes. Types of conductivity are discussed first, followed by an outline of the feature, applicability, and validity of DC and AC conductivity measurements. Techniques for the identification of the individual species responsible for conduction are then briefly reviewed. (orig.)
Physical properties of molten carbonate electrolyte
Energy Technology Data Exchange (ETDEWEB)
Kojima, T.; Yanagida, M.; Tanimoto, K. [Osaka National Research Institute (Japan)] [and others
Recently many kinds of compositions of molten carbonate electrolyte have been applied to molten carbonate fuel cell in order to avoid the several problems such as corrosion of separator plate and NiO cathode dissolution. Many researchers recognize that the addition of alkaline earth (Ca, Sr, and Ba) carbonate to Li{sub 2}CO{sub 3}-Na{sub 2}CO{sub 3} and Li{sub 2}CO{sub 3}-K{sub 2}CO{sub 3} eutectic electrolytes is effective to avoid these problems. On the other hand, one of the corrosion products, CrO{sub 4}{sup 2-} ion is found to dissolve into electrolyte and accumulated during the long-term MCFC operations. This would affect the performance of MCFC. There, however, are little known data of physical properties of molten carbonate containing alkaline earth carbonates and CrO{sub 4}{sup 2-}. We report the measured and accumulated data for these molten carbonate of electrical conductivity and surface tension to select favorable composition of molten carbonate electrolytes.
Macroscopic Modeling of Polymer-Electrolyte Membranes
Energy Technology Data Exchange (ETDEWEB)
Weber, A.Z.; Newman, J.
In this chapter, the various approaches for the macroscopic modeling of transport phenomena in polymer-electrolyte membranes are discussed. This includes general background and modeling methodologies, as well as exploration of the governing equations and some membrane-related topic of interest.
Fuel cell electrolyte membrane with basic polymer
Larson, James M.; Pham, Phat T.; Frey, Matthew H.; Hamrock, Steven J.; Haugen, Gregory M.; Lamanna, William M.
The present invention is an electrolyte membrane comprising an acid and a basic polymer, where the acid is a low-volatile acid that is fluorinated and is either oligomeric or non-polymeric, and where the basic polymer is protonated by the acid and is stable to hydrolysis.
A study of electrolytic tritium production
International Nuclear Information System (INIS)
Tritium production is being investigated using cathodes made from palladium and its alloys with various surface treatments. Three anode materials have been studied as well as different impurities in the electrolyte. Tritium has been produced in about 10% of the cells studied but there is, as yet, no pattern of behavior that would make the effect predictable. 15 refs., 4 figs., 6 tabs
Miniaturized Amperometric Solid Electrolyte Carbon Dioxide Sensors
Hunter, G. W.; Xu, J. C.; Liu, C. C.; Hammond, J. W.; Ward, B.; Lukco, D.; Lampard, P.; Artale, M.; Androjna, D.
A miniaturized electrochemical carbon dioxide (CO2) sensor using Na3Z r2Si2PO12 (NASICON) as a solid electrolyte has been fabricated and de monstrated. Microfabrication techniques were used for sensor fabricat ion to yield a sensing area around 1.0 mm x 1.1 mm. The NASICON solid electrolyte and the Na2CO3/BaCO3 (1:1.7 molar ratio) auxiliary elect rolyte were deposited by sputtering in between and on top of the inte rdigitated finger-shaped platinum electrodes. This structure maximize s the length of the three-phase boundary (electrode, solid electrolyt e, and auxiliary electrolyte), which is critical for gas sensing. The robust CO2 sensor operated up to 600 C in an amperometric mode and a ttempts were made to optimize sensor operating parameters. Concentrat ions of CO2 between 0.02% and 4% were detected and the overall sensor performance was evaluated. Linear response of sensor current output to ln[CO2 concentration] ranging from 0.02% to 1% was achieved.
Composite Solid Electrolyte for Li Battery Applications
Nagasubramanian, G.; Attia, A. I.; Halpert, G.; Peled, E.
The electrochemical, bulk and interfacial properties of the polyethylene oxide (PEO) based composite solid electrolyte (CSE) comprising LiI, PEO, and Al2O3 have been evaluated for Li battery applications. The bulk interfacial and transport properties of the CSEs seem to strongly depend on the alumina particle size. For the CSE films with 0.05 micron alumina while the bulk conductivity is around 10(exp -4) (mho/cm) at 103 C, the Li ion transport number seems to be close to unity at the same temperature. Compared to the PEO electrolyte this polymer composite electrolyte seems to exhibit robust mechanical and interfacial properties. We have studied three different films with three different alumina sizes in the range 0.01-0.3 micron. Effects of Al2O3 particle size on the electrochemical performance of polymer composite electrolyte is discussed. With TiS2 as cathode a 10 mAh small capacity cell was charged and discharged at C/40 and C/20 rates respectively.
Impact of particle size on interaction forces between ettringite and dispersing comb-polymers in various electrolyte solutions.
Ferrari, Lucia; Kaufmann, Josef; Winnefeld, Frank; Plank, Johann
The inter-particle forces play a fundamental role for the flow properties of a particle suspension in response to shear stresses. In concrete applications, cement admixtures based on comb-polymers like polycarboxylate-ether-based superplasticizer (PCE) are used to control the rheological behavior of the fresh mixtures, as it is negatively impacted by certain early hydration products, like the mineral ettringite. In this work, dispersion forces due to PCE were measured directly at the surface of ettringite crystals in different electrolyte solutions by the means of atomic force microscopy (AFM) applying spherical and sharp silicon dioxide tips. Results show an effective repulsion between ettringite surface and AFM tips for solutions above the IEP of ettringite (pH?12) and significant attraction in solution at lower pH. The addition of polyelectrolytes in solution provides dispersion forces exclusively between the sharp tips (radius ? 10 nm) and the ettringite surface, whereas the polymer layer at the ettringite surface results to be unable to disperse large colloidal probes (radius ? 10 ?m). A simple modeling of the inter-particle forces explains that, for large particles, the steric hindrance of the studied PCE molecules is not high enough to compensate for the Van der Waals and the attractive electrostatic contributions. Therefore, in cement suspensions the impact of ettringite on rheology is probably not only related to the particle charge, but also related to the involved particle sizes. PMID:24491324
Electrolytes for lithium and lithium-ion batteries
Jow, T Richard; Borodin, Oleg; Ue, Makoto
Electrolytes for Lithium and Lithium-ion Batteries provides a comprehensive overview of the scientific understanding and technological development of electrolyte materials in the last?several years. This book covers key electrolytes such as LiPF6 salt in mixed-carbonate solvents with additives for the state-of-the-art Li-ion batteries as well as new electrolyte materials developed recently that lay the foundation for future advances.?This book also reviews the characterization of electrolyte materials for their transport properties, structures, phase relationships, stabilities, and impurities.
Gel electrolytes based on poly(acrylonitrile)/sulpholane with hybrid TiO2/SiO2 filler for advanced lithium polymer batteries
International Nuclear Information System (INIS)
Highlights: � Paper describes properties of gel electrolyte based on PAN with TMS and TiO2-SiO2. � The TiO2-SiO2 oxide composite was precipitated in the emulsion system and used as the fillers. � The capacity of the graphite anode depends on the current rate and the amount of TiO2-SiO2. � For PE3 electrolyte was obtained practical capacity more than 90% of the theoretical capacity. - Abstract: This paper describes the synthesis and properties of a new type of ceramic fillers for composite polymer gel electrolytes. Hybrid TiO2-SiO2 ceramic powders have been obtained by co-precipitation from titanium(IV) sulfate solution using sodium silicate as the precipitating agent. The resulting submicron-size powders have been applied as fillers for composite polymer gel electrolytes for Li-ion batteries based on polyacrylonitrile (PAN) membranes. The powders and gel electrolytes have been examined structurally and electrochemically, showing favorable properties in terms of electrolyte uptake and electrochemical characteristics in Li-ion cells
Morphology and Ionic Conductivity of Block Copolymer Electrolytes Containing Ionic Liquids
Park, Moon Jeong
The global energy crisis and an increase in environmental pollution in the recent years have drawn the attention of the scientific community towards the development of efficient electrochemical devices. Polymers containing charged species have the potential to serve as electrolytes in next-generation devices and achieving high ion transport properties in these electrolytes is the key to improving their efficiency. Although the synthesis and characterization of a wide variety of ion-containing polymers have been extensively reported over the last decade, quantitative understanding of the factors governing the ion transport properties of these materials is in its infancy. In this talk, I will present the current understanding of the diverse factors affecting the thermodynamics, morphologies and ion transport of ion-containing polymers by focusing on the use of ionic liquids (ILs). Various strategies for accessing improved transport properties of IL-containing polymers are elucidated by focusing on the role of IL-polymer interactions. The major accomplishment of obtaining well-defined morphologies for these IL-containing polymers by the use of block copolymer is particularly emphasized as a novel means of controlling the transport properties. The application of IL-incorporated polymer electrolytes in high temperature fuel cells and electro-active actuators is also enclosed.
The potential role of electrolytic hydrogen in Canada
International Nuclear Information System (INIS)
The potential role of electrolytic hydrogen in Canada is assessed for the period 1980 to 2025 for large-scale uses only. Present uses of hydrogen, and specifically electrolytic hydrogen, are discussed briefly and hydrogen production processes are summarized. Only hydrogen derived from natural gas, coal, or electrolysis of sater are considered. Cost estimates of electrolytic hydrogen are obtained from a parametric equation, comparing values for unipolar water elecctrklyser technologies with those for bipolar electrolysers. Both by-products of electrolytic hydrogen production, namely heavy water and oxygen, are evaluated. Electrolytic hydrogen, based on non-fossil primary energy sources, is also considered as ankther 'liquid fuel option' for Canada along with the alcohols. The market potential for hydrogen in general and electrolytic hydrogen is assessed. Results show that the market potential for electrolytic hydrogen is large by the year 2025
Rheological assessment of nanofluids at high pressure high temperature
Kanjirakat, Anoop; Sadr, Reza
High pressure high temperature (HPHT) fluids are commonly encountered in industry, for example in cooling and/or lubrications applications. Nanofluids, engineered suspensions of nano-sized particles dispersed in a base fluid, have shown prospective as industrial cooling fluids due to their enhanced rheological and heat transfer properties. Nanofluids can be potentially utilized in oil industry for drilling fluids and for high pressure water jet cooling/lubrication in machining. In present work rheological characteristics of oil based nanofluids are investigated at HPHT condition. Nanofluids used in this study are prepared by dispersing commercially available SiO2 nanoparticles (~20 nm) in a mineral oil. The basefluid and nanofluids with two concentrations, namely 1%, and 2%, by volume, are considered in this investigation. The rheological characteristics of base fluid and the nanofluids are measured using an industrial HPHT viscometer. Viscosity values of the nanofluids are measured at pressures of 100 kPa to 42 MPa and temperatures ranging from 25�C to 140�C. The viscosity values of both nanofluids as well as basefluid are observed to have increased with the increase in pressure. High pressure high temperature (HPHT) fluids are commonly encountered in industry, for example in cooling and/or lubrications applications. Nanofluids, engineered suspensions of nano-sized particles dispersed in a base fluid, have shown prospective as industrial cooling fluids due to their enhanced rheological and heat transfer properties. Nanofluids can be potentially utilized in oil industry for drilling fluids and for high pressure water jet cooling/lubrication in machining. In present work rheological characteristics of oil based nanofluids are investigated at HPHT condition. Nanofluids used in this study are prepared by dispersing commercially available SiO2 nanoparticles (~20 nm) in a mineral oil. The basefluid and nanofluids with two concentrations, namely 1%, and 2%, by volume, are considered in this investigation. The rheological characteristics of base fluid and the nanofluids are measured using an industrial HPHT viscometer. Viscosity values of the nanofluids are measured at pressures of 100 kPa to 42 MPa and temperatures ranging from 25�C to 140�C. The viscosity values of both nanofluids as well as basefluid are observed to have increased with the increase in pressure. Funded by Qatar National Research Fund (NPRP 08-574-2-239).
Na+ Ion Conducting Hot-pressed Nano Composite Polymer Electrolytes
Directory of Open Access Journals (Sweden)
Angesh Chandra
Full Text Available Synthesis, characterization and polymeric battery studies of Na+ ion conducting Nano- Composite Polymer Electrolyte (NCPE membranes: (1-x [75PEO: 25NaPO3]: x SiO2, where x = 0 - 15 wt. (%, has been reported. NCPE membranes have been casted using a novel hot-press technique in place of the traditional solution cast method. The dispersal of SiO2 in SPE host: (75PEO: 25NaPO3, a conductivity enhancement of an order of magnitude achieved in NCPE film: [93 (75PEO: 25NaPO3: 7 SiO2]. This has been referred to as Optimum Conducting Composition (OCC. Material characterizations have been done with the help of XRD, SEM and DSC techniques. The ion transport behaviour in hot-pressed NCPEs has been discussed on the basis of experimental measurements on some basic ionic parameters viz. conductivity (?, ionic mobility (?, mobile ion concentration (n and ionic transference number (t ion. The temperature dependent conductivity studies have been done to compute the activation energy (Ea values from the 'log s - 1/T' Arrhenius plots. The ion conducting solid state polymeric battery was fabricated and cell-potential discharge characteristics have been studied at different load conditions.
Benzimidazole and imidazole lithium salts for battery electrolytes
Energy Technology Data Exchange (ETDEWEB)
Scheers, Johan; Johansson, Patrik; Jacobsson, Per [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Szczecinski, Przemyslaw; Wieczorek, Wladyslaw [Polymer Ionics Research Group, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, PL-00664 Warsaw (Poland); Armand, Michel [Laboratoire de Reactivite et de Chimie des Solides, Universite de Picardie Jules Verne, 33 rue St. Leu, 80089 Amiens (France)
The intrinsic anion oxidation potential ({delta}E{sub v}) and lithium ion pair dissociation energy ({delta}E{sub d}) are two important properties for predicting the potential use of new lithium salts for battery electrolytes. In this work several cyano substituted fluoroalkylated benzimidazole and imidazole anions have been investigated computationally to obtain {delta}E{sub v} and {delta}E{sub d}. Varying the number and position of cyano substituents results in large effects on the electrochemical stability of the anion and on the possible lithium ion pair configurations. The lengthening of the fluoroalkyl group introduces several new stable ion pair configurations and a small increase in anion oxidation stability. The most promising fluoroalkylated anions in the present work are the 4,5,6,7-tetracyano-2-fluoroalkylated benzimidazolides (TTB and PTB), with oxidation potentials suitable for high voltage Li-ion battery applications (<4.2 V) and much improved {delta}E{sub d} compared to PF{sub 6}{sup -} - a benchmark for commercially available anions. Further improvements in {delta}E{sub d}, with maintained stability towards oxidation, are obtainable by replacing the fluoroalkyl group by an additional cyano group, but possibly demanding increased synthesis efforts. (author)
Na+ Ion Conducting Hot-pressed Nano Composite Polymer Electrolytes
Scientific Electronic Library Online (English)
Angesh, Chandra; Archan, Chandra; Kiran, Thakurb.
Full Text Available Synthesis, characterization and polymeric battery studies of Na+ ion conducting Nano- Composite Polymer Electrolyte (NCPE) membranes: (1-x) [75PEO: 25NaPO3]: x SiO2, where x = 0 - 15 wt. (%), has been reported. NCPE membranes have been casted using a novel hot-press technique in place of the traditi [...] onal solution cast method. The dispersal of SiO2 in SPE host: (75PEO: 25NaPO3), a conductivity enhancement of an order of magnitude achieved in NCPE film: [93 (75PEO: 25NaPO3): 7 SiO2]. This has been referred to as Optimum Conducting Composition (OCC). Material characterizations have been done with the help of XRD, SEM and DSC techniques. The ion transport behaviour in hot-pressed NCPEs has been discussed on the basis of experimental measurements on some basic ionic parameters viz. conductivity (?), ionic mobility (?), mobile ion concentration (n) and ionic transference number (t ion). The temperature dependent conductivity studies have been done to compute the activation energy (Ea) values from the 'log s - 1/T' Arrhenius plots. The ion conducting solid state polymeric battery was fabricated and cell-potential discharge characteristics have been studied at different load conditions.
Rheological characterization of chicory root (Cichorium intybus L.) inulin solution
Scientific Electronic Library Online (English)
J. T. C. L., Toneli; K. J., Park; J. R. P., Ramalho; F. E. X., Murr; I. M. D., Fabbro.
Full Text Available Inulin is a polysaccharide frequently used as a sugar or fat replacer in the food industry, which offers the advantage of a functional effect similar to those of dietary fibers. By cooling or freezing an inulin concentrated solution, a more concentrated solution precipitates as a paste-like substanc [...] e, while the liquid phase forms a diluted solution. In this work, the effect of storage temperature of inulin concentrated solution as well as temperature on the rheological behavior of liquid and precipitated phases obtained from a process of phase separation were evaluated. The precipitated phase of inulin was evaluated under two conditions: pure and formulated with encapsulating agents. It was observed that a reduction in storage temperature resulted in a higher inulin precipitation, which produced higher apparent viscosity values for the precipitated phase. All the samples analyzed had a shear-thinning rheological behavior.
Rheology of fluids measured by correlation force spectroscopy
Radiom, Milad; Robbins, Brian; Honig, Christopher D. F.; Walz, John Y.; Paul, Mark R.; Ducker, William A.
We describe a method, correlation force spectrometry (CFS), which characterizes fluids through measurement of the correlations between the thermally stimulated vibrations of two closely spaced micrometer-scale cantilevers in fluid. We discuss a major application: measurement of the rheological properties of fluids at high frequency and high spatial resolution. Use of CFS as a rheometer is validated by comparison between experimental data and finite element modeling of the deterministic ring-down of cantilevers using the known viscosity of fluids. The data can also be accurately fitted using a harmonic oscillator model, which can be used for rapid rheometric measurements after calibration. The method is non-invasive, uses a very small amount of fluid, and has no actively moving parts. It can also be used to analyze the rheology of complex fluids. We use CFS to show that (non-Newtonian) aqueous polyethylene oxide solution can be modeled approximately by incorporating an elastic spring between the cantilevers.
Simulation and rheological analysis of Hanford Tank 241-SY-101
International Nuclear Information System (INIS)
Rheological characterization and small scale simulation of Hanford Tank 241-SY-101 has been initiated to aid in the remediation efforts for the Department of Energy Hanford Site. The study has been initiated in response to growing concerns about the potential flammability hazard pertaining to the periodic release of up to 10,000 cubic feet of hydrogen, nitrous oxide, nitrogen, and ammonia gases. Various stimulants emulating the radioactive waste stored in this tank have been used to ascertain the rheological parameters of the waste, simulate the ongoing processes of gas generation and release phenomenon inside the tank, and determine the feasibility of jet mixing to achieve a controlled release of the gas mixture
Rheology of stabilized cerium-gadolinium oxide (CGO) colloidal system
DEFF Research Database (Denmark)
Marani, Debora; Hjelm, Johan
Achievement of stable dispersion with high solid loadings and low viscosity is crucial issue in ceramic films processing. In this work, systematic analysis of the rheological properties of CGO colloidal suspension was performed. The study aimed to define methods for evaluating fully stabilized conditions and critical parameters. The influences of dispersant and inorganic contents on suspensions properties were investigated. The optimization of dispersant content was achieved by studying flow behaviour of suspensions at different amounts of dispersant. Rotational and oscillatory tests were performed to study the inorganic loading impact on the suspension rheology. To identify a realistic load limit, the parameter ?h was proposed. It defines the highest volume fraction to meet the processing requirements. A simple method for its determination was also proposed. The maximum solid volume fraction (?m) was evaluated using a simple linear method. An extensive comparison with the commonly used non-linear physical models was performed.
Dynamics of diffuse oceanic plate boundaries: insensitivity to rheology
Zatman, Stephen; Gordon, Richard G.; Mutnuri, Kartik
Diffuse plate boundaries, which are zones of deformation hundreds to thousands of kilometres wide, occur in both continental and oceanic lithosphere. Here, we build on our prior work in which we described analytic approximations to simple dynamical models that assume that the vertically averaged viscous force resisting deformation in diffuse oceanic plate boundaries (DOPBs) is described by either a linear Newtonian viscous rheology or a yield-stress (high-exponent power-law) rheology. An important observation is that the poles of relative rotation of adjacent component plates tend to lie in the diffuse plate boundary that separates them. A key cause of this tendency is that a faster spin is needed to balance a component of torque through the middle of a diffuse plate boundary than to balance an equal component of torque lying 90� from the middle of the diffuse boundary. The strength of that tendency depends on rheology, however, with the tendency being stronger for a yield-stress rheology than for a Newtonian viscous rheology. For the special case of the pole of rotation lying outside of and along the strike of the boundary, these large differences can be simply explained in terms of the distribution of boundary-perpendicular normal forces acting across the boundary. In the Newtonian case, the distribution of forces has an along-strike gradient that can balance a component of torque about the middle of the boundary, while in the yield-stress case, the distribution of forces has zero along-strike gradient and cannot balance a component of torque about the middle of the diffuse plate boundary. To expand our analysis to intermediate power laws of geophysical interest (i.e. power-law exponents of 3 to 30), as well as to investigate more thoroughly the behaviour for a high-exponent power law, we numerically integrate the force distribution to obtain the torques. Results for intermediate power laws resemble the yield-stress rheology much more than they resemble the Newtonian rheology and depend only weakly on the width of the deforming zone. To quantify the probability that a pole of rotation lies in a diffuse plate boundary, we numerically integrate the expectation assuming that all orientations of torque are equally probable. For a power-law exponent of n= 10: 49 per cent of possible torque orientations produce angular velocities outside the diffuse plate boundary if the boundary is 55� long (similar in length to the boundary between the Nubian and Somalian component plates); 21 per cent of possible torque orientations produce angular velocities outside the diffuse plate boundary if the boundary is 30� long (similar in length to the boundary between the Indian and Capricorn component plates and to that between the Capricorn and Australian component plates); and 6 per cent of possible torque orientations produce angular velocities outside the diffuse plate boundary if the boundary is 15� long (similar in length to the boundary between the North American and South American component plates and to that between the Macquarie and Australian component plates). These results reinforce the prior conclusion that the pole is more strongly locked into the boundary if a DOPB is short than if it is long. For all boundary lengths, but even more so for short boundaries, the relationship between angular velocity and torque depends only weakly on the power-law exponent of the rheology as long as n>= 3. From this, we conclude that orientation of the relative torque across a DOPB can be inferred from the location of the pole of rotation without precise knowledge of the appropriate power-law exponent.
Rheological and Thermal Debinding Behaviors in Titanium Powder Injection Molding
Park, Seong-Jin; Wu, Yunxin; Heaney, Donald F.; Zou, Xin; Gai, Guosheng; German, Randall M.
Powder injection molding (PIM) is suitable for the fabrication of complex shape titanium and its alloys and has a great potential in many applications. This article deals with the injection molding of hydride-dehydride (HDH) titanium powder, spheroidized HDH titanium powder, and gas-atomized (GA) titanium powder. Rheological and thermal debinding behaviors are compared between feedstocks made from the three powders. Torque and capillary rheometers are used to investigate rheological behavior as it relates to the power-law model of viscosity and moldability index. Thermogravimetric analysis (TGA) was employed to analyze debinding behavior given a master decomposition curve consisting of two sigmoids. Spheroidized HDH Ti powder behaves in a manner similar to GA Ti powder. The analysis of the results in this study indicates the possibility of using a combination of HDH and GA titanium powders for PIM.
Rheological studies of aqueous stabilised nano-zirconia particle suspensions
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Asad Ullah Khan
Full Text Available In the present investigation aqueous suspensions of nano- and colloidal range particles are stabilised by changing the ambient pH. Rheology is used to establish the stability of the suspensions and it is found that the rheology of the suspensions is strongly dependent on the pH values. The viscosity is highest close to the iso-electric point of the powders. At the iso-electric point the net surface charge on the powder particles is zero and is the cause of the high viscosity. Away from the iso-electric point, the particles are charged, giving rise to a double layer phenomenon and causing the reduction in viscosity. It is also found that increasing the solid contents of the suspensions reduces the pH region of low viscosity.
Rheological and Thermal Behavior of Polypropylene-Kaolin Composites
International Nuclear Information System (INIS)
Kaolins effect on rheological behaviour of polypropylene-kaolin composites was investigated. The research found that not only the kaolin content influence the rheological behaviour but also the compounding using internal mixer and twin screw extruder. In details, viscosity and shear stress increased with addition of kaolin content. These characteristics also exhibited higher in polypropylene-kaolin composite suspensions compounded using twin screw extruder than using internal mixer. Chain scission was assumed to occur and affect the melt properties. Further justification characterized by Differential Scanning Calorimeter (DSC) showed that the effect of kaolin and loading content were more evident on the onset melting temperature and crystallinity. Besides, due to the different cooling operation in both processes, the effect of compounding on melting characteristic was conspicuous. (author)
The Rheology of the Earth in the Intermediate Time Range
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Full Text Available The evidence bearing upon the rheology of the " tectonically
significant layers" of the Earth (" tectonosphere " in the intermediate
time range (4 hours to 15000 years is analyzed. This evidence is
based upon observations of rock-behavior in the laboratory, of seismic
aftershock sequences, of Earth tides and of the decay of the Chandler wobble.
It is shown that of the rheological models (Maxwell-material, Kelvin-material,
and logarithmically creeping material advocated in the literature, only that
based on logarithmic creep does not contradict any of the observational
evidence available to date. In addition, a strength limit may be present.
Rheology and TIC/TOC results of ORNL tank samples
International Nuclear Information System (INIS)
The Savannah River National Laboratory (SRNL)) was requested by Oak Ridge National Laboratory (ORNL) to perform total inorganic carbon (TIC), total organic carbon (TOC), and rheological measurements for several Oak Ridge tank samples. As received slurry samples were diluted and submitted to SRNL-Analytical for TIC and TOC analyses. Settled solids yield stress (also known as settled shear strength) of the as received settled sludge samples were determined using the vane method and these measurements were obtained 24 hours after the samples were allowed to settled undisturbed. Rheological or flow properties (Bingham Plastic viscosity and Bingham Plastic yield stress) were determined from flow curves of the homogenized or well mixed samples. Other targeted total suspended solids (TSS) concentrations samples were also analyzed for flow properties and these samples were obtained by diluting the as-received sample with de-ionized (DI) water
Rheological studies of aqueous stabilised nano-zirconia particle suspensions
Scientific Electronic Library Online (English)
Asad Ullah, Khan; Anwar Ul, Haq; Nasir, Mahmood; Zulfiqar, Ali.
Full Text Available In the present investigation aqueous suspensions of nano- and colloidal range particles are stabilised by changing the ambient pH. Rheology is used to establish the stability of the suspensions and it is found that the rheology of the suspensions is strongly dependent on the pH values. The viscosity [...] is highest close to the iso-electric point of the powders. At the iso-electric point the net surface charge on the powder particles is zero and is the cause of the high viscosity. Away from the iso-electric point, the particles are charged, giving rise to a double layer phenomenon and causing the reduction in viscosity. It is also found that increasing the solid contents of the suspensions reduces the pH region of low viscosity.
Estimate of Hanford Waste Rheology and Settling Behavior
International Nuclear Information System (INIS)
The U.S. Department of Energy (DOE) Office of River Protection's Waste Treatment and Immobilization Plant (WTP) will process and treat radioactive waste that is stored in tanks at the Hanford Site. Piping, pumps, and mixing vessels have been selected to transport, store, and mix the high-level waste slurries in the WTP. This report addresses the analyses performed by the Rheology Working Group (RWG) and Risk Assessment Working Group composed of Pacific Northwest National Laboratory PNNL, Bechtel National Inc. (BNI), CH2M HILL, DOE Office of River Protection (ORP) and Yasuo Onishi Consulting, LLC staff on data obtained from documented Hanford waste analyses to determine a best-estimate of the rheology of the Hanford tank wastes and their settling behavior. The actual testing activities were performed and reported separately in referenced documentation. Because of this, many of the required topics below do not apply and are so noted
Polymer rheology simulations at the meso- and macroscopic scale
Sultan, Eric; Somfai, Ellak; Morozov, Alexander N; Van Saarloos, Wim
We show that simulations of polymer rheology at a fluctuating mesoscopic scale and at the macroscopic scale where flow instabilities occur can be achieved at the same time with dissipative particle dynamics (DPD) technique.} We model the visco-elasticity of polymer liquids by introducing a finite fraction of dumbbells in the standard DPD fluid. The stretching and tumbling statistics of these dumbbells is in agreement with what is known for isolated polymers in shear flows. At the same time, the model exhibits behaviour reminiscent of drag reduction in the turbulent state: as the polymer fraction increases, the onset of turbulence in plane Couette flow is pushed to higher Reynolds numbers. The method opens up the possibility to model nontrivial rheological conditions with ensuing coarse grained polymer statistics.
Scaling of plate-tectonic convection with pseudoplastic rheology
Korenaga, Jun
The scaling of plate-tectonic convection is investigated by simulating thermal convection with pseudoplastic rheology and strongly temperature-dependent viscosity. The effect of mantle melting is also explored with additional depth-dependent viscosity. Heat-flow scaling can be constructed with only two parameters, the internal Rayleigh number and the lithospheric viscosity contrast, the latter of which is determined entirely by rheological properties. The critical viscosity contrast for the transition between plate-tectonic and stagnant-lid convection is found to be proportional to the square root of the internal Rayleigh number. The relation between mantle temperature and surface heat flux on Earth is discussed on the basis of these scaling laws, and the inverse relationship between them, as previously suggested from the consideration of global energy balance, is confirmed by this fully dynamic approach. In the presence of surface water to reduce the effective friction coefficient, the operation of plate tec...
Investigations of rheological properties of diclofenac sodium gel preparation
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Firuza Maksudova
Full Text Available It is well-known that the majority of non-steroidal anti-inflammatory drugs (NSAIDs are ulcerogenic. Gel or ointment preparations of NSAIDs are free from this side-effect, which is a prerequisite for the increase of aforementioned forms of NSAIDs. A major quality indicator of gels and ointments are rheological properties. Along with determining the quality of preparation, they influence manufacturing, expiration date and terms of storage. This article demonstrates the results of investigation of rheological indices of 3% gel preparation of diclofenac sodium such as plasticity, structural viscosity, and thixotropy. Obtained results confirm that the developed gel preparation has thixotropy, plasticity and is classified as a Bingham system.
Rheological study of reinforcement of agarose hydrogels by cellulose nanowhiskers.
Le Goff, Kevin J; Gaillard, Cedric; Helbert, William; Garnier, Catherine; Aubry, Thierry
The influence of the addition of tunicate cellulose nanowhiskers on the structural and rheological properties of an agarose hydrogel matrix has been studied, with the objective to design innovative green material, with good mechanical properties. The cellulose nanowhiskers were characterized using transmission electron microscopy, and their charge surface density was determined by a titration method. Oscillatory shear and stress relaxation tests were performed in order to characterize the rheological properties of the agarose matrix, and of the agarose hydrogels filled by nanowhiskers at volume fractions below 0.2%. The results show a significant reinforcement effect due to the addition of nanowhiskers, and suggest changes in the matrix network structure induced by the cellulose nanoparticles. PMID:25458280
Simulations of the structure and rheology of wet webs
Miettinen, Pasi
In this Thesis we modified a recently introduced model for fiber suspensions to be applicable to wet fiber networks so as to analyze by computer simulations their structural and rheological properties. These properties were compared, under tensile loading in particular, to those of wet and dry paper. The model used operated at the fiber level, where the dynamics of fiber motion were determined by fiber stiffness and fiber-fiber interactions such as friction and adhesive forces....
Rheological characterization of chicory root (Cichorium intybus L.) inulin solution
J. T. C. L. Toneli; K. J. Park; J. R. P. Ramalho; F. E. X. Murr; I. M. D. Fabbro
Inulin is a polysaccharide frequently used as a sugar or fat replacer in the food industry, which offers the advantage of a functional effect similar to those of dietary fibers. By cooling or freezing an inulin concentrated solution, a more concentrated solution precipitates as a paste-like substance, while the liquid phase forms a diluted solution. In this work, the effect of storage temperature of inulin concentrated solution as well as temperature on the rheological behavior of liquid and ...
Rheological Properties Of Some Surfactant-Based Fracturing Fluids
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Andra Tamas
Full Text Available The paper presents the rheological behavior study of some cationic surfactant-based aqueous solutions that can be used as fracturing fluids. It was followed the influence of salt type and concentration, as well as that of temperature by setting the dependence between the shear stress ? and the shear rate ? ? . The analysis of dependence between ? and ? ? demonstrates that all the studied solutions have non-Newtonian behavior with flow behavior index smaller than 1.
Rheology of semisolid alloys under rapid change in shear rate
Energy Technology Data Exchange (ETDEWEB)
Liu, Tze Yong
Industrial thixoforming processes are carried out within a second. Characterisation of the rheological behaviour of the semisolid metal slurry during this short space of time is therefore important. Rheological experiments were carried out on Sn15%Pb alloy (fraction solid 0.2-0.5) in a HAAKE cylindrical rotational viscometer using {approx}1kHz data collection rate to obtain the shear stress response to a rapid change in shear rate (range: 1 s{sup -1}-200 s{sup -1}). The slurry undergoes an initial rapid structural breakdown during a jump upwards in shear rate, followed by a more gradual breakdown. The former occurs within a second of the start of the jump. The metal slurry breaks down more rapidly with a higher final shear rate, but is independent of the initial shear rate. The reverse is found with downward jumps in shear rate: recovery times increase with increasing final shear rate. Again, the breakdown time is independent of the starting shear rate. The rheological behaviour of aluminium alloys with solid fraction >0.5 was studied by compressing cylindrical slugs at high speed against a load cell. The slurry exhibits a near-Newtonian behaviour at the thixoforming temperature, after an appropriate soaking time is employed and a near-spheroidal microstructure develops. Use of image analysis to quantify the spheroidicity indicates that particle shape affects the flow of the slurry, a higher spheroidicity corresponding to a lower load. Using solid-state mechanical deformation to break up the dendrites, produces thixoforming feedstock with lower resistance to flow than magnetohydrodynamic stirring. Power law index values were more negative than -1, for both rapid compression and viscometry experiments were obtained, indicating shear thinning behaviour in the semisolid metal slurry. Results from this work have shown the importance of understanding the rheological behaviour of a semisolid slurry in the transient state. (author)
Rheology of semisolid alloys under rapid change in shear rate
International Nuclear Information System (INIS)
Industrial thixoforming processes are carried out within a second. Characterisation of the rheological behaviour of the semisolid metal slurry during this short space of time is therefore important. Rheological experiments were carried out on Sn15%Pb alloy (fraction solid 0.2-0.5) in a HAAKE cylindrical rotational viscometer using ?1kHz data collection rate to obtain the shear stress response to a rapid change in shear rate (range: 1 s-1-200 s-1. The slurry undergoes an initial rapid structural breakdown during a jump upwards in shear rate, followed by a more gradual breakdown. The former occurs within a second of the start of the jump. The metal slurry breaks down more rapidly with a higher final shear rate, but is independent of the initial shear rate. The reverse is found with downward jumps in shear rate: recovery times increase with increasing final shear rate. Again, the breakdown time is independent of the starting shear rate. The rheological behaviour of aluminium alloys with solid fraction >0.5 was studied by compressing cylindrical slugs at high speed against a load cell. The slurry exhibits a near-Newtonian behaviour at the thixoforming temperature, after an appropriate soaking time is employed and a near-spheroidal microstructure develops. Use of image analysis to quantify the spheroidicity indicates that particle shape affects the flow of the slurry, a higher spheroidicity corresponding to a lower load. Using solid-state mechanicallower load. Using solid-state mechanical deformation to break up the dendrites, produces thixoforming feedstock with lower resistance to flow than magnetohydrodynamic stirring. Power law index values were more negative than -1, for both rapid compression and viscometry experiments were obtained, indicating shear thinning behaviour in the semisolid metal slurry. Results from this work have shown the importance of understanding the rheological behaviour of a semisolid slurry in the transient state. (author)
Hidden Invariants in Rheology: The Persistent Granular Nature of Liquids
Chafin, Clifford
This article will use arguments derived from the deformation driven component of mixing, especially important for microfluidics, to show that the standard invariant based approaches to rheology are lacking. It is shown that the deviator, $D_{ij}$, after the process of symmetrization, loses microscopically determined information that distinguish rotation from shear and extension in a unique fashion. We recover this information through an analysis of the discrete processes tha...
Effect of water mineralization on rheological properties of polyacrylamide muds
Energy Technology Data Exchange (ETDEWEB)
Almayev, R.Kh.; Gubina, A.V.; Khanov, R.K.; Rakhimkulov, I.F.
Results are presented of determining the viscosity and rheological properties of polyacrylamide muds of different types depending on their mineralization, molecular weight of the polymers and permeability of the productive rocks. A change is indicated in their properties depending on the indicated parameters. It was recommended that PAA of high molecular mass be used with the use of mineralized waters in terrigenous rocks with good collector properties.
Investigations of rheological properties of diclofenac sodium gel preparation
Firuza Maksudova; Ekut Karieva
It is well-known that the majority of non-steroidal anti-inflammatory drugs (NSAIDs) are ulcerogenic. Gel or ointment preparations of NSAIDs are free from this side-effect, which is a prerequisite for the increase of aforementioned forms of NSAIDs. A major quality indicator of gels and ointments are rheological properties. Along with determining the quality of preparation, they influence manufacturing, expiration date and terms of storage. This article demonstrates the results of investiga...
Effect of Fluoropolymer Antidripping Agent on Rheological Behavior of LLDPE
Obr, Ale�; Zatloukal, Martin
In this work, high molecular weight polytetrafluoroethylene based antidripping agent was blended with Ziegler-Natta based LLDPE in different concentrations. Rheological characterization was consequently performed for all the blends and the obtained results were compared with the pure LLDPE. It has been found that high molecular weight PTFE based melt modifier MM 5935 EF significantly enhancing the shear viscosity/elasticity and especially the extensional viscosity of the LLDPE melt.
Rheological behavior of castor oil mixed with different pyromellitic esters
Boran Sorina; Tamas Andra
The paper presents the rheological behavior study of castor oil mixed with different pyromellitic esters. The pyromellitic tetraesters used were obtained through the esterification of pyromellitic anhydride with a special alcohol of a complex alkyl-aryl structure (2-phenoxy-ethanol) in conjunction with a linear aliphatic alcohol with variable length (n-butanol, n-decanol). The influence of pyromellitic esters� structure and concentration was determined, a...
Rheological impact of nano-size fillers in Polycarbonate
Martinez, Cayetano; K�nig, Christian; Maier, Mathias; Nemec, Dominik; Kolaric, Ivica
Carbon nanotubes (CNTs) are a promising filler material for polymers to change the electrical properties and enhance the mechanical behaviour. These particles are known to increase the melt viscosity of thermoplastics significantly. For the moulding process high melt viscosities are causing various complications. In this study the influence of CNTs and Carbon Black (CB) on the rheological behaviour of a polycarbonate (PC) matrix will be evaluated. CB is a common filler used for antistatic and...
Rheological characterization of borate crosslinked fluids using oscillatory measurements
Edy, I. Ketut Oscar
Fracturing fluid has a very important role in hydraulic fracturing treatment. Viscosity of hydraulic fracturing fluid affects transporting, suspending, and deposition of proppant, as well as flow back after treatment. It should also be capable to develop the necessary fracture width to accept proppants or to allow deep acid penetration. Compatibility with formation fluids and material has to be taken into account (Guo et al. 2007). Rheology of the fracturing fluid is fundamental for hydraulic...
Rheology and Reactivity of Cementitious Binders with Plasticizers
Vikan, Hedda Vest�l
The rheological behaviour of cementitious pastes has been studied by various means. Six different cements have been studied in main parts of the work and all of them have been characterized according to the Rietveld method in order to determine the exact content of minerals. Easily soluble alkalis were measured by plasma-emission- spectroscopy of the fluid filtered from paste. Three types of plasticizers namely naphthalene sulfonate formaldehyde condensate (SNF), lignosulphonate and polyacryl...
Rheology of suspensions with aluminum nano-particles
Ulrich Teipel; Ulrich F�rter-Barth
Nano-scale aluminum particles are innovative materials increasingly used in energetic formulations. In this contribution, the rheological behavior of suspensions with either paraffin oil or HTPB as the matrix fluid and nano-scale aluminum (ALEX) as the dispersed phase is described and discussed. The paraffin oil/aluminum suspensions exhibit non-Newtonian flow behavior over a wide range of concentrations, whereas the HTPB/aluminum suspensions exhibit Newtonian behavior (i.e. the viscosity is i...
Determination Of Rheological Properties Of Polymer Solutions In Sandpacks
Hamada, G. M
There is a correlation between mobility ratio and oil recovery by water displacement in homogeneous and heterogeneous reservoirs. Because of this correlation, it is essential to develop a mobility control process which would be based on the behavior of the mobility ratio factor. It appears that polymer solution is an ideal additive to control the mobility ratio in the operation of waterfloods. This paper describes the rheological behavior of polymer solutions in sand packs and frontal adva...
Study of the rheological behavior of chocolate and margarine [abstract
Debaste, F.; Haut, B.; Lie?geois, S.; Hospied, E.; Fonoll, Jr; Be?cu, M.
In the food industry, the production process is often established in an empirical way, according to rules of good practice. These methods present gaps, in particular at the level of the production regularity. To model and optimize the processes, it is highly useful to determine the physico-chemical properties of the product. In this work, chocolate and margarine are studied, both aiming direct industrial application but also aiming a general enhancement of rheological mechanism understanding....
Microbiological and rheological studies on Portuguese kefir grains
Pintado, Manuela E.; Silva, J. A. Lopes Da; Fernandes, Paulo B.; Malcata, F. Xavier; Hogg, Tim A.
The native bacteria and yeasts present in Portuguese kefir grains stored under four distinct sets of environmental conditions have been isolated and identified on the basis of morphology and biochemical tests. The microbial population of the kefir grains as a whole has been characterized in terms of rates of biomass production and formation of lactic acid and ethanol. The rheological properties of the purified polysaccharide (kefiran) produced by the microflora of the grains and accumulate...
Rheological Properties of Oxidized Bitumen with Polymer Additive
Teltayev Bagdat; Izmailova Galiya; Amirbayev Yerik
In the present study rheological properties of bitumen of grade BND-90/130 obtained from crude oil of Western Siberia (Russia) by the direct oxidation method and polymer binder, obtained by adding in pure bitumen the polymer Elvaloy 4170 are investigated. Binders in initial state and after short-term aging at high and average temperatures were tested on the Dynamic Shear Rheometer (DSR) and at low temperatures after double aging-on the Bending Beam Rheometer (BBR). The obtained results showed...
On interference types in electrolyte solutions
International Nuclear Information System (INIS)
A brief analysis of component interference types in electrolyte aqueous solutions is presented. On the example of studying ClO4- ion state in different (lithium, sodium, magnesium, cadmium, europium...) perchlorate solutions using molecular spectroscopy methods it is shown that ion-water interaction essentially depends on counterion nature. For deep understanding of interference processes in solutions with ion-molecular level usefulness of considering the system solubility isotherms is marked. On the example of solubility isotherms of several ternary systems (PrCl3-LiCl-H2O; Sc(ClO4)3-HClO4-H2O; PrCl3-RbCl-H2O; CdCl2-KCl-H2O) it is shown that different chemical nature of components results in various dominating interactions (mutual dehydration of electrolytes, dehydration of one of the components etc.). 6 refs.; 4 figs
Effect of degradation of surfactant solutions by age on rheological properties and drag reducing effectiveness.
Czech Academy of Sciences Publication Activity Database
My�ka, Ji?�; �tern, Petr; M�k, V�clav; �est�k, J.
Soul : The Korean Society of Rheology, 2004 - (Lee, J.; Lee, S.), nestr. ISBN 89-950057-5-0. [International congress on rheology /14./. Soul (KP), 22.08.2004-27.08.2004] R&D Projects: GA ?R GA101/03/0585; GA AV ?R IAA2060204; GA AV ?R KSK2067107 Institutional research plan: CEZ:AV0Z2060917 Keywords : drag reduction * rheological properties * surfactants Subject RIV: BK - Fluid Dynamics
Study of generalized Prandtl rheological model for constitutive description of elastoplastic properties of materials
W. Grzesikiewicz; A. Zbiciak
Purpose: of this paper is to demonstrate the process of constitutive modelling of elastoplastic properties of materials using generalized Prandtl rheological model. A special attention is put on description of composites.Design/methodology/approach: Based on the proposed rheological model, the set of constitutive relationships is formulated. Identification of parameters of rheological model is carried out based on experimental hysteretic loops. The constitutive equations are used in the paper...
Flow of entangled wormlike micellar fluids: Mesoscopic simulations, rheology and ?-PIV experiments
Boek, E. S.; Padding, J. T.; Anderson, V. J.; Briels, W. J.; Crawshaw, J. P.
There is a great need for understanding the relationship between the structure and chemistry of surfactants forming wormlike micelles, and their macroscopic flow properties. Available macroscopic Rheological Equations of State (REoS) are often inadequate to predict flow behaviour in complex geometries or even to describe the full set of rheological measurements. In this paper, we show how the link between surfactant structure and rheology can be explored through the use of mesoscopic particul...
Prediction of texture perception of mayonnaises from rheological and novel instrumental measurements
Terpstra, M.E.J.; Jellema, R. H.; Janssen, A.M.; Van Wijk, R.A.; Prinz, J.F.; van der Linden, E.
Commercial and model mayonnaises varying in fat content and type and amount of thickener were characterized by sensory analysis, rheological measurements and novel instrumental measurements covering other physicochemical properties and/or reflecting changes of food properties during oral processing. Predictions of texture attributes by rheological measurements were analyzed and compared with predictions by rheological measurements combined with novel measurements. Most of the texture attribut...
Empirical and fundamental mechanical tests in the evaluation of dough and bread rheological properties
Balestra, Federica
Bread dough and particularly wheat dough, due to its viscoelastic behaviour, is probably the most dynamic and complicated rheological system and its characteristics are very important since they highly affect final products� textural and sensorial properties. The study of dough rheology has been a very challenging task for many researchers since it can provide numerous information about dough formulation, structure and processing. This explains why dough rheology has been a matter of invest...
Rheological properties of kaolin and chemically simulated waste
International Nuclear Information System (INIS)
The Savannah River Laboratory is conducting tests to determine the best operating conditions of pumps used to transfer insoluble radioactive sludges from old to new waste tanks. Because it is not feasible to conduct these tests with real or chemically simulated sludges, kaolin clay is being used as a stand-in for the solid waste. The rheology tests described herein were conducted to determine whether the properties of kaolin were sufficiently similar to those of real sludge to permit meaningful pump tests. The rheology study showed that kaolin can be substituted for real waste to accurately determine pump performance. Once adequately sheared, kaolin properties were found to remain constant. Test results determined that kaolin should not be allowed to settle more than two weeks between pump tests. Water or supernate from the waste tanks can be used to dilute sludge on an equal volume basis because they identically affect the rheological properties of sludge. It was further found that the fluid properties of kaolin and waste are insensitive to temperature
Rheological Behavior of Dense Assemblies of Granular Materials
International Nuclear Information System (INIS)
Assemblies of granular materials behave differently when they are owing rapidly, from when they are slowly deforming. The behavior of rapidly owing granular materials, where the particle-particle interactions occur largely through binary collisions, is commonly related to the properties of the constituent particles through the kinetic theory of granular materials. The same cannot be said for slowly moving or static assemblies of granular materials, where enduring contacts between particles are prevalent. For instance, a continuum description of the yield characteristics of dense assemblies of particles in the quasistatic ow regime cannot be written explicitly on the basis of particle properties, even for cohesionless particles. Continuum models for this regime have been proposed and applied, but these models typically assume that the assembly is at incipient yield and they are expressed in terms of the yield function, which we do not yet know how to express in terms of particle-level properties. The description of the continuum rheology in the intermediate regime is even less understood. Yet, many practically important flows in nature and in a wide range of technological applications occur in the dense flow regime and at the transition between dilute and dense regimes; the lack of validated continuum rheological models for particle assemblies in these regimes limits predictive modeling of such flows. This research project is aimed at developing such rheological models.
Rheological study of polypropylene irradiated with polyfunctional monomers
International Nuclear Information System (INIS)
The aim of this paper is to investigate the rheological properties of polypropylene (PP) modified by ionization radiation (gamma rays) in the presence of two different monomers. The samples were mixed in a twin-screw extruder with ethylene glycol dimethacrylate (EGDMA) or trimethylolpropane trimethacrylate (TMPTMA) with concentration in the range of 0.5-5.0 mmol. After that, they were irradiated with 20 kGy dose of gamma radiation. The structural modification of polypropylene was analyzed in the melt state by measuring melt flow rate (MFR), ?* (complex viscosity) and G' (storage modulus) in the angular frequency range of 10-1 to 3 x 102 rad s-1. From the oscillatory rheology data, one could obtain the values of ?0 (zero shear viscosity) that would be related to the molar mass. All results were discussed with respect to the crosslinking and degradation process that occur in the post-reactor treatment to produce controlled rheology polypropylene. The resulting polymeric materials were submitted the cytotoxicity in vitro test by neutral red uptake methodology with NCTC L 929 cell line from American Type Culture Collection bank. All modified PP samples presented no cytotoxicity
Maximum bubble pressure rheology of low molecular mass organogels.
Fei, Pengzhan; Wood, Steven J; Chen, Yan; Cavicchi, Kevin A
Maximum bubble pressure rheology is used to characterize organogels of 0.25 wt % 12-hydroxystearic acid (12-HSA) in mineral oil, 3 wt % (1,3:2,4) dibenzylidene sorbitol (DBS) in poly(ethylene glycol), and 1 wt % 1,3:2,4-bis(3,4-dimethylbenzylidene) sorbitol (DMDBS) in poly(ethylene glycol). The maximum pressure required to inflate a bubble at the end of capillary inserted in a gel is measured. This pressure is related to the gel modulus in the case of elastic cavitation and the gel modulus and toughness in the case of irreversible fracture. The 12-HSA/mineral oil gels are used to demonstrate that this is a facile technique useful for studying time-dependent gel formation and aging and the thermal transition from a gel to a solution. Comparison is made to both qualitative gel tilting measurements and quantitative oscillatory shear rheology to highlight the utility of this measurement and its complementary nature to oscillatory shear rheology. The DBS and DMDBS demonstrate the generality of this measurement to measure gel transition temperatures. PMID:25582128
Shear History Extensional Rheology Experiment: A Proposed ISS Experiment
Hall, Nancy R.; Logsdon, Kirk A.; Magee, Kevin S.
The Shear History Extensional Rheology Experiment (SHERE) is a proposed International Space Station (ISS) glovebox experiment designed to study the effect of preshear on the transient evolution of the microstructure and viscoelastic tensile stresses for monodisperse dilute polymer solutions. Collectively referred to as Boger fluids, these polymer solutions have become a popular choice for rheological studies of non-Newtonian fluids and are the non-Newtonian fluid used in this experiment. The SHERE hardware consists of the Rheometer, Camera Arm, Interface Box, Cabling, Keyboard, Tool Box, Fluid Modules, and Stowage Tray. Each component will be described in detail in this paper. In the area of space exploration, the development of in-situ fabrication and repair technology represents a critical element in evolution of autonomous exploration capability. SHERE has the capability to provide data for engineering design tools needed for polymer parts manufacturing systems to ensure their rheological properties have not been impacted in the variable gravity environment and this will be briefly addressed.
Identification of rheological properties of human body surface tissue.
Benevicius, Vincas; Gaidys, Rimvydas; Ostasevicius, Vytautas; Marozas, Vaidotas
According to World Health Organization obesity is one of the greatest public health challenges of the 21st century. It has tripled since the 1980s and the numbers of those affected continue to rise at an alarming rate, especially among children. There are number of devices that act as a prevention measure to boost person's motivation for physical activity and its levels. The placement of these devices is not restricted thus the measurement errors that appear because of the body rheology, clothes, etc. cannot be eliminated. The main objective of this work is to introduce a tool that can be applied directly to process measured accelerations so human body surface tissue induced errors can be reduced. Both the modeling and experimental techniques are proposed to identify body tissue rheological properties and prelate them to body mass index. Multi-level computational model composed from measurement device model and human body surface tissue rheological model is developed. Human body surface tissue induced inaccuracies can increase the magnitude of measured accelerations up to 34% when accelerations of the magnitude of up to 27 m/s(2) are measured. Although the timeframe of those disruptions are short - up to 0.2 s - they still result in increased overall measurement error. PMID:24607008
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Full Text Available In this research work, the effects of Styrene�Ethylene-Butylene�Styrene (SEBS modification on the conventional properties and rheological characteristics of pure bitumen were investigated. The polymer modified bitumens (PMBs were prepared by mixing bitumen with SEBS to four polymer contents using laboratory mixer. The physical properties of the PMBs have been determined using conventional test methods. The results indicated that polymer modification improved the conventional properties of the base bitumen such as; penetration, softening point and temperature susceptibility. The results of storage stability test showed that the storage-stable mixtures could be obtained if the polymer content was maintained below about 5 wt%. The rheological properties of the modified binders were characterized using dynamic shear rheometer (DSR. The results of the investigation indicate that the SEBS polymer improve rheological properties of base bitumen, such as increased elastic responses (increased complex shear modulus and decreased phase angle at low to high temperatures. The softening point and TSHRP of the modified bitumen become higher, indicating the improvement of high-temperature property of the modified bitumen.
Steady Rheological Properties of Rotating Biological Contactor (RBC Sludge
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Mukheled AL-SAMERAIY
Full Text Available The rheological characterization of sewage sludge at different steps of wastewater treatment is important since it allows predicting and estimating sludge behavior when submitted to almost all treatment and disposal operations. Rotating biological contactor (RBC is being widely used for wastewater treatment, which is a biological treatment process following primary treatment. The rheological characterization of RBC sludge at different solid contents (TSS = 32.2 g/L�50.2 g/L and temperatures (5�40 �C was carried out using a rotational viscometer. The RBC sludge showed a shear-thinning behavior, where the apparent viscosity decreased rapidly with the shear rate reaching the limiting viscosity (n at the infinite shear rate. An exponential relationship described the evolution of the limiting viscosity with the sludge TSS content. In addition, a dramatic increase in the limiting viscosity beyond a TSS concentration of 42.4 g/L has been observed. On the other hand, Bingham model described well the non-Newtonian behavior of sludge suspensions. It was clear that the yield stress is more sensitive than the Bingham viscosity for the variation in temperature and solid content. However, the rheological results revealed that both the limiting and Bingham viscosities have the same behavior with the TSS content and with the temperature.
Rheology of water-silicate mixtures at low temperatures
Durham, William B.
Lab studies of the effects of hard particulates on the rheology of ice have been mainly directed at the evolution of the Galilean satellites, but yield results that may be applicable to the rheology of the Martian polar caps. The experiments have explored the ductile rheology as well as brittle behavior of water + particulate (mainly quartz) mixtures in particulate volume fractions ranging from 0.001 to 0.56, particulate sizes 1 to 150 microns, temperatures 77 to 224 K, and deformation rates 3.5 x 10(exp -7) to 3.5 x 10(exp -4)/s, under confining pressures of 50 to 100 MPa. Particulates act mainly to strengthen the material in the ductile field, although work by others has shown that very close to the melting temperature hard particulates can actually cause softening. So called dispersion hardening by the Orowan mechanism of pinning glide dislocations, often exploited in metallurgy for strengthening materials, appears not to be an issue in ice except at very low temperatures, less than approx. 135 K.
Rheological study of ?-irradiated rare earth oxide based ferrofluids
International Nuclear Information System (INIS)
The present work reports on the optical and rheological properties of unexposed and gamma irradiated rare earth (RE) oxide nanoparticle- based ferrofluids (FF). The ferrofluids were produced by dispersing surfactant coated terbium doped gadolinium oxide (Tb:Gd2O3) nanoparticles in ethanol medium and later on subjected to energetic gamma radiation (1.25 MeV) at select doses (97Gy, 2.635 kGy). The synthesized nanoparticles are of ?9 nm size as predicted from transmission electron microscopy (TEM). The nanoparticle system exhibits cubic crystal structure as evident from X-ray diffraction (XRD) study. The photoluminescence (PL) measurement reveals creation of defect states when FFs are subjected to gamma irradiation. Tb related transition could also be visualized from the PL measurements. Rheology measurements show unusual shear thinning behavior of the ferrofluids. The flow behavior of all the samples can be correlated with the biexponential decay curve fitting which reveals that decay phenomenon is governed by two independent mechanism: fast and slow events. The variation of the decay parameter with irradiation dose is attributed to defect formation, role impurity ion (Tb) and weakening of inter nanoparticle bonding. Tb incorporation might have created a energy state which may lead to the variation of rheological behavior. (author)
Rheology of Savannah River Site Tank 51 HLW radioactive sludge
International Nuclear Information System (INIS)
Savannah River Site (SRS) Tank 51 HLW radioactive sludge represents a major portion of the first batch of sludge to be vitrified in the Defense Waste Processing Facility (DWPF) at SRS. The rheological properties of Tank 51 sludge will determine if the waste sludge can be pumped by the current DWPF process cell pump design and the homogeneity of melter feed slurries. The rheological properties of Tank 51 sludge and sludge/frit slurries at various solids concentrations were measured remotely in the Shielded Cells Operations (SCO) at the Savannah River Technology Center (SRTC) using a modified Haake Rotovisco viscometer system. Rheological properties of Tank 51 radioactive sludge/Frit 202 slurries increased drastically when the solids content was above 41 wt %. The yield stresses of Tank 51 sludge and sludge/frit slurries fall within the limits of the DWPF equipment design basis. The apparent viscosities also fall within the DWPF design basis for sludge consistency. All the results indicate that Tank 51 waste sludge and sludge/frit slurries are pumpable throughout the DWPF processes based on the current process cell pump design, and should produce homogeneous melter feed slurries
Electrodeposition of Metal from Polymer Electrolytes.
Czech Academy of Sciences Publication Activity Database
Do?kal, M.; Sedla?�kov�, M.; Vondr�k, Ji?�
Brno : University of Technology Brno, 2002, s. 13-1-13-2. ISBN 80-214-2082-0. [Advanced Batteries and Accumulators /3./. Brno (CZ), 16.06.2002-20.06.2002] R&D Projects: GA ?R GA104/02/0731; GA AV ?R IAA4032002 Institutional research plan: CEZ:AV0Z4032918 Keywords : electrodeposition * cadmium * polymer electrolytes Subject RIV: CA - Inorganic Chemistry
Electrolytic colouration of KCl: Tl+ crystals
International Nuclear Information System (INIS)
The modifications of the absorption spectrum of KCl: Tl+ crystals, produced by electrolytic colouration, migration in electric field and heat treatment, are studied. Arguments are given for assigning the band at 3.5 eV to Tl- complex and that peaking at 4.15 eV and 5.08 eV to thallium colloids. New bands in KCl: Tl+ + Ca2+ or KCl: Tl+ + Sr2+ are mentioned. (author)
Functional electrolyte for lithium-ion batteries
Energy Technology Data Exchange (ETDEWEB)
Zhang, Lu; Zhang, Zhengcheng; Amine, Khalil
Functional electrolyte solvents include compounds having at least one aromatic ring with 2, 3, 4 or 5 substituents, at least one of which is a substituted or unsubstituted methoxy group, at least one of which is a tert-butyl group and at least one of which is a substituted or unsubstituted polyether or poly(ethylene oxide) (PEO) group bonded through oxygen to the aromatic ring, are provided.
Serum electrolytes in senile cataract patients
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Usha S. Adiga
Full Text Available Introduction: Cataract refers to opacification of crystalline lens in the human eye. Globally, cataract accounts for 50% of blindness and remains the leading cause of visual impairment all over the world, despite improvements in surgical outcomes. Age is the strongest known non-modifiable risk factor for cataract formation. One of the proposed risk factors for cataract formation is rise in serum sodium ion level. Role of potassium and chloride are inconclusive Even though ageing cannot be prevented, physiological changes that occur in electrolytes can be modified. The aim of the study was to estimate serum electrolyte levels in senile cataract patients as compared to those without cataract. Methods: This study includes hundred senile cataract patients and age matched hundred healthy people without cataract. Serum electrolytes were estimated by using an electrolyte analyzer which works on the principle of ion selective electrodes. Results: We noted a highly significant (p<0.0001 rise in sodium levels in cases (146.35 � 3.49 meq/l as compared to controls (142.77 � 3.75meq/l.Chloride levels were also significantly elevated (p<0.05 in cases (102.32 � 4.10meq/l as compared to controls (100.82 � 4.12 meq/l. Serum potassium level, even though elevated in cases, it was statistically insignificant. Conclusion: From this study we can conclude that sodium and chloride may be used as markers of senile cataract formation. Dietary salt restriction may help to lower the sodium and chloride levels and delay the process of cataract formation.
Elastic proton conducting inorganic-organic electrolytes.
Czech Academy of Sciences Publication Activity Database
M�ka, M.; Ma��nov�, M.; �varcov�, S.; Paidar, M.; Bouzek, K.; Kl�p�t?, B?etislav; Vondr�k, Ji?�
Montreal : Ecole Polytechnique Montreal, 2006, s. 23-s. 23. [International Symposium on New Materials for Electrochemical Systems /6./. Montreal (CA), 09.07.2006-12.07.2009] R&D Projects: GA ?R GA106/04/1279; GA M�P SN/3/171/05 Institutional research plan: CEZ:AV0Z40320502 Keywords : inorganic-organic electrolytes Subject RIV: CA - Inorganic Chemistry
Electrochromic window with lithium conductive polymer electrolyte
Baudry, Paul; Aegerter, Michel A.; Deroo, Daniel; Valla, Bruno
An electrochromic window was built using WO3 as the electrochromic material and V2O5 as the counter-electrode. Both were deposited onto ITO coated glass panes by vacuum evaporation and were amorphous to X-ray diffraction. The electrolyte was a lithium conducting polymer constituted by a Poly (ethylene oxide) - lithium salt complex. The electrochemical characterization of electrodes was realized by cyclic voltammetry, coulometric titration, and impedance spectroscopy, which allowd the determin...
Electrochemical Reactions in Polymer Electrolyte Fuel Cells
Wesselmark, Maria
The polymer electrolyte fuel cell converts the chemical energy in a fuel, e.g. hydrogen or methanol, and oxygen into electrical energy. The high efficiency and the possibility to use fuel from renewable sources make them attractive as energy converters in future sustainable energy systems. Great progress has been made in the development of the PEFC during the last decade, but still improved lifetime as well as lowered cost is needed before a broad commercialization can be considered. The elec...
Oxide/Electrolyte interface: Electron transfer phenomena
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Fern�ndez-Ib��ez, P.
Full Text Available Electron transfer on a titanium dioxide/electrolyte solution interface has been studied. As observed by other researchers on similar interfaces (TiO2- and ZnO- electrolyte solution, slow consumption of OH- ions was found. A theoretical model has been developed for calculating the change in Fermi energy levels of both electrolyte solution and semiconductor, showing that ion consumption from the solution is favoured by a decreased difference in their Fermi energies. A kinetic constant (? is found to characterise the consumption process, its value increasing with electrolyte and semiconductor mass concentrations. Furthermore, this process may be used to estimate the point of zero charge of a titanium dioxide colloidal dispersion.
En este trabajo se ha estudiado un proceso de transferencia de electrones en la interfase di�xido de titanio/electrolito acuoso. Tal y como han observado otros investigadores en interfases similares (TiO2- y ZnO- electrolito, se ha detectado un consumo lento de iones OH-. Para dar explicaci�n a este proceso, se ha desarrollado un modelo te�rico basado en el c�lculo de las energ�as de Fermi en el semiconductor y en el electrolito. De este modo, se demuestra que dicho consumo de iones est� favorecido por una disminuci�n de la diferencia entre ambos niveles de Fermi. Para caracterizar el proceso de consumo lento de OH- se define una constante cin�tica (?, cuyo valor aumenta a medida que crece la concentraci�n m�sica de semiconductor y de electrolito en la suspensi�n. Adicionalmente, este fen�meno proporciona una herramienta para determinar experimentalmente el punto de carga nula de la suspensi�n de di�xido de titanio en el medio acuoso.
Molecular assembly, interfacial rheology and foaming properties of oligofructose fatty acid esters.
van Kempen, Silvia E H J; Schols, Henk A; van der Linden, Erik; Sagis, Leonard M C
Two major types of food-grade surfactants used to stabilize foams are proteins and low molecular weight (LMW) surfactants. Proteins lower the surface tension of interfaces and tend to unfold and stabilize the interface by the formation of a visco-elastic network, which leads to high surface moduli. In contrast, LMW surfactants lower the surface tension more than proteins, but do not form interfaces with a high modulus. Instead, they stabilize the interface through the Gibbs-Marangoni mechanism that relies on rapid diffusion of surfactants, when surface tension gradients develop as a result of deformations of the interface. A molecule than can lower the surface tension considerably, like a LMW surfactant, but also provide the interface with a high modulus, like a protein, would be an excellent foam stabilizer. In this article we will discuss molecules with those properties: oligofructose fatty acid esters, both in pure and mixed systems. First, we will address the synthesis and structural characterization of the esters. Next, we will address self-assembly and rheological properties of air/water interfaces stabilized by the esters. Subsequently, this paper will deal with mixed systems of mono-esters with either di-esters and lauric acid, or proteins. Then, the foaming functionality of the esters is discussed. PMID:24292507
RELATIONSHIP BETWEEN MORPHOLOGY, RHEOLOGY AND GLUCOAMYLASE PRODUCTION BY Aspergillus awamori IN SUBMERGED CULTURES
Scientific Electronic Library Online (English)
C.R.D., Pamboukian; M.C.R., Facciotti; W., Schmidell.
Full Text Available The influence of inoculum preparation on Aspergillus awamori morphology, broth rheology and glucoamylase synthesis in submerged cultures was investigated. A series of runs were performed in fermenters, using initial total reducing sugar concentrations of 20 g/L and 80 g/L. The inocula were prepared [...] in a rotary shaker, at 35oC and 200 rev/min, using a spore concentration of 9.2 x 105 spores/mL and varying both cultivation time and medium pH during the spore germination step. Three types of inocula were used: inoculum cultivated for 24 hours at an initial pH of 5.0, and inocula cultivated for 7 hours at both a pH of 2.5 and a pH of 5.5. Regarding glucoamylase production, the inoculum which provided the best results was shaker cultivated for 7 hours at a pH of 2.5. This inoculum produced glucoamylase of about 1,221 U/L in the fermenter, which was between 20% and 30% higher than those obtained using other inocula.
RELATIONSHIP BETWEEN MORPHOLOGY, RHEOLOGY AND GLUCOAMYLASE PRODUCTION BY Aspergillus awamori IN SUBMERGED CULTURES
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C.R.D. Pamboukian
Full Text Available The influence of inoculum preparation on Aspergillus awamori morphology, broth rheology and glucoamylase synthesis in submerged cultures was investigated. A series of runs were performed in fermenters, using initial total reducing sugar concentrations of 20 g/L and 80 g/L. The inocula were prepared in a rotary shaker, at 35oC and 200 rev/min, using a spore concentration of 9.2 x 105 spores/mL and varying both cultivation time and medium pH during the spore germination step. Three types of inocula were used: inoculum cultivated for 24 hours at an initial pH of 5.0, and inocula cultivated for 7 hours at both a pH of 2.5 and a pH of 5.5. Regarding glucoamylase production, the inoculum which provided the best results was shaker cultivated for 7 hours at a pH of 2.5. This inoculum produced glucoamylase of about 1,221 U/L in the fermenter, which was between 20% and 30% higher than those obtained using other inocula.
Fluorinated sulfonic acids as fuel cell electrolytes
International Nuclear Information System (INIS)
While early acid cells used sulfuric acid electrolyte with platinum catalysts, the lack of stability to reduction of this electrolyte at temperatures over 800C together with its very low performance for direct hydrocarbon oxidation in its working temperature range caused a changeover to phosphoric acid. This is the only moderately strong inorganic acid which is both stable throughout the fuel cell potential range and nonvolatile at temperatures above 1500C. Above this temperature, rates of direct hydrocarbon oxidation on platinum and its alloys become significant. With the commencement of the Gas Utility fuel cell program at United Technologies Corporation (then Pratt and Whitney Division of United Aircraft) in 1967, the desire for yet higher oxidation rates and lower anode catalyst loadings led to the adoption of external steam reforming of the hydrocarbon (methane), the steam being generated using waste heat from the fuel cell for overall system efficiency reasons. The more recent desire for still higher performance in Electric Utility systems has led to pressurized (845 kPa, 8.2 bar) operation 2050C. Again, phosphoric acid (about 93-95% concentration by weight) is the only possible common electrolyte for use under these conditions
[Disturbances of electrolytes in severe thermal burns].
Hauhouot-Attoungbre, M L; Mlan, W C H; Edjeme, N A; Ahibo, H; Vilasco, B; Monnet, D
Thermal burns result in severe electrolytes disturbances which are life-threatening when the percentage of burnt body surface area (BSA) is above 20% in adults and 10% in children. If electrolytes disturbances are often mentioned in the physiopathology of burns, they are less documented in the daily practice of the follow up. The objective of this work was to describe variation of blood and urine electrolytes concentrations in severe burns. The survey concerned 30 patients hospitalized in the Burn Centre of Abidjan. The patients have been followed during the first three days after the burn, including the initial phase of shock resuscitation. The results showed, in accordance with data of the literature, the incidence of hypophosphoremia, hypoprotidemia and hypocalcemia. The hypoprotidemia and the hypocalcemia were correlated with the importance of the BSA. An elevation of potassium and a decrease of sodium have been also observed, but, in contrast to data of the literature, they were not significant. Moderate variations of chloride and magnesium have been noted. All urinary parameters were decreased. The present results suggest the necessity of proteins, phosphore and calcium administration in the therapeutic protocols. PMID:16061440
Multicomponent equations of state for electrolytes
DEFF Research Database (Denmark)
Lin, Yi; Thomsen, Kaj
Four equations of state have been implemented and evaluated for multicomponent electrolyte solutions at 298.15 K and 1 bar. The equations contain terms accounting for short-range and long-range interactions in electrolyte solutions. Short range interactions are described by one of the three equations of state, Peng-Robinson, Soave-Redlich-Kwong, or Cubic-Plus-Association (CPA). Long-range interactions are described by either the simplified mean spherical approximation (MSA) solution of the Ornstein-Zernicke equation or the simplified Debye-Huchel term. An optional Born term is added to these electrostatic terms. The resulting electrolyte equations of state were tested by determining the optimal model parameters for the multicomponent test system consisting of H2O, Na+, H+, Ca2+, Cl-, OH-, SO42-. To describe the thermodynamics of this multicomponent system, ion specific parameters were determined. The parameters in the equations of state were fitted to experimental data consisting of apparent molar volumes, osmotic coefficients, mean ionic activity coefficients, and solid-liquid equilibrium data. The results of the parameter fitting are presented. The ability of the equations of state to reproduce the experimental data is demonstrated. The performance of the equations of state for multi component systems is compared and analyzed in view of the various short-range and long-range terms employed. (c) 2007 American Institute of Chemical Engineers.
Properties of ENR-50 Based Electrolyte System
International Nuclear Information System (INIS)
In this work, epoxidized natural rubber 50 (ENR-50) has been used as a host polymer for the preparation of electrolyte system. Attenuated total reflection-fourier transform infrared spectroscopic analyses showed the presence of lithium salt-ENR interactions. The glass transition temperature displayed an increasing trend with the increase in salt concentration indicating that the ionic conductivity was not influenced by segmental motion of the ENR-50 chains. The increase in glass transition temperature with the addition of salt was due to the formation of transient cross-linking between ENR-50 chains via the coordinated interaction between ENR-50 chains and salt. The highest room temperature ionic conductivity obtained was in the order of 10-5 S cm-1 for the film containing 50 wt % of lithium salt. The ionic conductivity of this electrolyte system increased with increasing temperature and obeyed the Vogel-Tamman-Fulcher behavior. The increase in ionic conductivity of the electrolyte system with salt concentration could also be correlated to the charge carriers concentration and/ or migration rate of charge carriers. (author)
Causes of supercapacitors ageing in organic electrolyte
Energy Technology Data Exchange (ETDEWEB)
Azais, Philippe; Duclaux, Laurent; Beguin, Francois [CRMD, CNRS-University, 1B rue de la Ferollerie, 45071 Orleans Cedex 2 (France); Florian, Pierre; Massiot, Dominique [CRMHT, CNRS, 1D avenue de la Recherche Scientifique, 45071 Orleans Cedex 2 (France); Lillo-Rodenas, Maria-Angeles; Linares-Solano, Angel [Department of Inorganic Chemistry, University of Alicante, Apartado de Correos 99, 03080 Alicante (Spain); Peres, Jean-Paul; Jehoulet, Christophe [SAFT, Direction de la Recherche, 111 Boulevard Daney, 33074 Bordeaux Cedex (France)
In order to understand what causes supercapacitors ageing in an organic electrolyte (tetraethylammonium tetrafluoroborate - Et{sub 4}NBF{sub 4} - 1 mol L{sup -1} in acetonitrile), the activated carbon electrodes were characterized before and after prolonged floating (4000-7000 h) at an imposed voltage of 2.5 V. After ageing, the positive and negative electrodes were extensively washed with pure acetonitrile in neutral atmosphere to eliminate the physisorbed species. Then, the carbon materials were dried and transferred without any contact with air to be studied by XPS, {sup 19}F NMR, {sup 11}B NMR and {sup 23}Na NMR. Decomposition products have been found in the electrodes after ageing. The amount of products depends on the kind of activated carbon and electrode polarity, which suggests redox reactions of the electrolyte with the active surface functionality. Nitrogen adsorption measurements at 77 K on the used electrodes showed a decrease of accessible porosity, due to trapping of the decomposition products in the pores. Hence, the evolution of the supercapacitor performance with time of operation, i.e. the capacity decrease and the resistance increase, are due to the decomposition of the organic electrolyte on the active surface of the carbon substrate, forming products which block a part of porosity. The concentration of surface groups and their nature were found to have an important influence on the performance fading of supercapacitors. (author)
Multi component equations of state for electrolytes
DEFF Research Database (Denmark)
Lin, Yi; Thomsen, Kaj
Four equations of state have been implemented and evaluated for multi component electrolyte solutions at 298.15K and 1 bar. The equations contain terms accounting for short-range and long-range interactions in electrolyte solutions. Short range interactions are described by one of the three equations of state, Peng-Robinson, Soave-Redlich-Kwong, or Cubic-Plus-Association (CPA). Long range interactions are described by either the simplified mean spherical approximation (MSA) solution of the Ornstein�Zernicke equation or the simplified Debye-H�ckel term. An optional Born term is added to these electrostatic terms. The resulting electrolyte equations of state were tested by determining the optimal model parameters for the multi component test system consisting of H2O, Na+, H+, Ca2+, Cl-, OH-, SO42-. In order to describe the thermodynamics of this multi component system, ion specific parameters were determined. The parameters in the equations of state were fitted to experimental data consisting of apparent molar volumes, osmotic coefficients, mean ionic activity coefficients, and solid-liquid equilibrium data. The results of the parameter fitting are presented. The ability of the equations of state to reproduce the experimental data is demonstrated. The performance of the equations of state for multi component systems is compared and analyzed in view of the various short range and long range terms employed.
Redox-active electrolyte for supercapacitor application.
Frackowiak, Elzbieta; Meller, Mikolaj; Menzel, Jakub; Gastol, Dominika; Fic, Krzysztof
This paper reports the electrochemical behaviour of supercapacitor carbon electrodes operating in different aqueous solutions modified by various redox-active species (hydroxybenzenes, bromine derivatives and iodide). Three dihydroxybenzenes with varying stereochemistry, i.e., -OH substitution, have been considered as electrolyte additives (0.38 mol L(-1)) in acidic, alkaline and neutral solutions. High capacitance values have been obtained, especially for the acidic and alkaline solutions containing 1,4-dihydroxybenzene (hydroquinone). Bromine derivatives of dihydroxybenzenes were also considered as the additive in alkaline solution for use as a supercapacitor electrolyte, and a significant increase in capacitance value was observed. The redox couple investigated next was an iodide/iodine system, where 2 mol L(-1) NaI aqueous electrolyte was utilized. In this case, the most promising faradaic contribution during capacitor operation was achieved. In particular, stable capacitance values from 300-400 F g(-1) have been confirmed by long-term galvanostatic cycling (over 100 000 cycles), cycling voltammetry and floating. The mechanism of pseudocapacitance phenomena was discussed and supported by electrochemical and physicochemical measurements, e.g., in situ Raman spectroscopy. PMID:25426821
Development of a new thermochemical and electrolytic hybrid hydrogen production process for sodium cooled FBR - Status and future plan
International Nuclear Information System (INIS)
A new thermochemical and electrolytic hybrid hydrogen production process is under development by Japan Atomic Energy Agency (JAEA) to realize the hydrogen production from water by using the heat (500-600oC) and electric power generation of sodium cooled fast breeder reactor (FBR). The HHLT process is based on sulfuric acid (H2SO4) synthesis and the decomposition processes developed earlier (Westinghouse process). Sulfur trioxide (SO3) decomposition process for oxygen production is facilitated by electrolysis with ionic oxygen conductive solid electrolyte, and sulfuric acid synthesis process for hydrogen production is facilitated by electrolysis with proton conductive polymer electrolyte. A new experimental apparatus for 1NL/h level hydrogen production was developed to investigate durability, controllability and hydrogen production efficiency of the process. Hydrogen production experiment using the apparatus was started, and 0.4NL/h hydrogen production for 1 hour was confirmed. Hydrogen production experiment using the 1NL/h level apparatus will be continued for a few years, then development of a 100NL/h hydrogen production experimental apparatus will be started and the apparatus will be connected to a sodium loop facility. (author)
Characterization of non-linear rheological behavior of SPI-FG dispersions using LAOS tests and FT rheology.
Bi, Chong-hao; Li, Dong; Wang, Li-jun; Wang, Yong; Adhikari, Benu
The effect of flaxseed gum (FG) on the rheological and nonlinear stress response behaviors of mixed soy protein isolate (SPI)-flaxseed gum (FG) dispersions were studied. Results showed that the viscosity of the SPI-FG mixed dispersions increased significantly with increase in the FG concentration. Both the shear stress and the apparent viscosity values as a function of shear rate were fitted well using Power law model as expected. The frequency dependence of G', G'' and tan? of soy protein isolate decreased as the FG concentration increased. The large amplitude oscillatory shear (LAOS) test and Fourier transform (FT) rheology analysis showed that the addition of flaxseed gum strongly affected the structure of the SPI-FG mixed dispersion system as shown by deformation of the nonlinear stress response curve and significantly altered magnitude of higher harmonic curve. The addition of FG increased the instantaneous strain softening effect of the SPI-FG mixed dispersion system. PMID:23399140
Determining Rheological Parameters of Generalized Yield-Power-Law Fluid Model
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Stryczek Stanislaw
Full Text Available The principles of determining rheological parameters of drilling muds described by a generalized yield-power-law are presented in the paper. Functions between tangent stresses and shear rate are given. The conditions of laboratory measurements of rheological parameters of generalized yield-power-law fluids are described and necessary mathematical relations for rheological model parameters given. With the block diagrams, the methodics of numerical solution of these relations has been presented. Rheological parameters of an exemplary drilling mud have been calculated with the use of this numerical program.
Structure and rheology of cationic molecular hydrogels of quinuclidine grafted bile salts. Influence of the ionic strength and counter-ion type.
Terech, P; Dourdain, S; Maitra, U; Bhat, S
Quinuclidine grafted cationic bile salts are forming salted hydrogels. An extensive investigation of the effect of the electrolyte and counterions on the gelation has been envisaged. The special interest of the quinuclidine grafted bile salt is due to its broader experimental range of gelation to study the effect of electrolyte. Rheological features of the hydrogels are typical of enthalpic networks exhibiting a scaling law of the elastic shear modulus with the concentration (scaling exponent 2.2) modeling cellular solids in which the bending modulus is the dominant parameter. The addition of monovalent salt (NaCl) favors the formation of gels in a first range (0.00117 g cm(-3) (0.02 M) approximately 68 A) and the nodal zones. Stress sweep and creep-recovery measurements are used to relate the lack of linear viscoelastic domain to a mechanism of disentanglement of the fibers from their associations into fagots. The electrostatic interactions can be screened by addition of salt to induce a progressive evolution toward flocculation. SEM, UV absorbance, and SAXS study of the Bragg peak at large Q-values complete the investigation. PMID:19256482
Rheological and dielectric properties of different gold nanoparticle sizes
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Abdelhalim Mohamed Anwar K
Full Text Available Abstract Background Gold nanoparticles (GNPs have found themselves useful for diagnostic, drug delivery and biomedicine applications, but one of the important concerns is about their safety in clinical applications. Nanoparticle size has been shown to be an extremely important parameter affecting the nanoparticle uptake and cellular internalization. The rheological properties assume to be very important as it affects the pressure drop and hence the pumping power when nano-fluids are circulated in a closed loop. The rheological and dielectric properties have not been documented and identified before. The aim of the present study was to investigate the rheology and the dielectric properties of different GNPs sizes in aqueous solution. Methods 10, 20 and 50 nm GNPs (Product MKN-Au, CANADA was used in this study. The rheological parameters were viscosity, torque, shear stress, shear rate, plastic viscosity, yield stress, consistency index, and activation energy. These rheological parameters were measured using Brookfield LVDV-III Programmable rheometer supplied with temperature bath and controlled by a computer. Results The shear stress and shear rate of GNPs have shown a linear relationship and GNPs exhibited Newtonian behaviour. The GNPs with larger particle size (50 nm exhibited more viscosity than those with smaller particle sizes (10 and 20 nm. Viscosity decreased with increasing the temperature for all the examined GNP sizes. The flow behaviour index (n values were nearly ? 1 for all examined GNP sizes. Dielectric data indicated that the GNPs have strong dielectric dispersion in the frequency range of 20-100 kHz. The conductivity and relaxation time decreased with increasing the GNP size. Conclusions This study indicates that the GNP size has considerable influence on the viscosity of GNPs. The strong dielectric dispersion was GNP size dependent. The decrease in relaxation time might be attributed to increase in the localized charges distribution within the medium confirmed by the conductivity data. This study suggests that further experiments are required to be done after the administration of GNPs through different routes in rats in vivo.
Electrolytic method to make alkali alcoholates using ion conducting alkali electrolyte/separator
Joshi, Ashok V. (Salt Lake City, UT); Balagopal, Shekar (Sandy, UT); Pendelton, Justin (Salt Lake City, UT)
Alkali alcoholates, also called alkali alkoxides, are produced from alkali metal salt solutions and alcohol using a three-compartment electrolytic cell. The electrolytic cell includes an anolyte compartment configured with an anode, a buffer compartment, and a catholyte compartment configured with a cathode. An alkali ion conducting solid electrolyte configured to selectively transport alkali ions is positioned between the anolyte compartment and the buffer compartment. An alkali ion permeable separator is positioned between the buffer compartment and the catholyte compartment. The catholyte solution may include an alkali alcoholate and alcohol. The anolyte solution may include at least one alkali salt. The buffer compartment solution may include a soluble alkali salt and an alkali alcoholate in alcohol.
Electrolytic recovery of tin from waste lead frames. Use of aqueous HCl leaching solution as electrolyte
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Kang, Kyung-Hoon [Ajou Univ., Suwon-si (Korea, Republic of). Div. of Chemical and Materials Engineering; Kim, Beomseok [Yonsei Univ., Seoul (Korea, Republic of). Dept. of Chemistry; Seo, Min Hye; Cho, Sung-Su; Lee, Sungkyu; Hong, Hyun Seon [Institute for Advanced Engineering, Yongin-si (Korea, Republic of). Advanced Materials and Processing Center
Lead frames are generated in large quantities by modern semiconductor packaging industry and they contain significant concentrations of valuable tin, nickel, and copper. For electrowinning of tin from waste lead frames, hydrochloric acid leaching of tin is quite advantageous, but solution stability, electrolytic efficiency and deposit morphology should be optimized before commercialization. HCl electrolyte was diluted (distilled water: HCl = 350: 150) for electrowinning of waste lead frames at 40 C with 0.2 A/cm{sup 2} and Ti-Ir cathode. After 4 h electrowinning, 99 % pure Sn with 99.1 % recovery rate was produced. Therefore, aqueous HCl electrolyte was quite effective for electrowinning of Sn leaching solution, and a higher recovery rate of purer Sn within shorter electrowinning time was obtained. (orig.)
Rheological and Tribological Properties of Complex Biopolymer Solutions
Klossner, Rebecca Reese
The rheological and tribological properties of an experimental synovial fluid model were investigated in order to determine the solution dynamics of the three most abundant macromolecules present in synovial fluid, the fluid that lubricates freely moving (synovial) joints. These components, hyaluronic acid (HA) and the plasma proteins, albumin and gamma-globulins are combined in a phosphate buffered saline solution (PBS) and subjected to steady shear rheology testing, as well as nanoindenter-based scratch testing, which allows for the study of the lubrication properties of the experimental synovial fluid model. Steady shear experiments, where the shear rate was increased from low to high, and then decreased from high to low, showed hysteresis in only protein containing solutions, whereas samples of HA in PBS behaved as a "typical" polyelectrolyte in solution. Subsequent rheological experiments on the synovial fluid model exhibited an increase in viscosity at low shear stresses, indicating that a structure was present at these low shear stresses, which was not found at higher shear stresses. This result is in agreement with studies conducted on the same model which show unusual rheological behavior at low shear rates. Low shear stresses can cause modifications to the external protein surface, resulting in their unfolding and creating many opportunities for the molecules to reorder themselves. As the proteins reorder themselves, the newly exposed hydrophobic patches will have a tendency to aggregate together, creating a network within the fluid, and, in turn causing the observed increased viscosity at low shear stresses. Additionally, an anti-inflammatory drug, hydroxychloroquine (HCQ) was added to the solutions. This addition diminishes the protein aggregation process substantially. Finally, the HA component of the synovial fluid model was replaced with a neutral polymer in order to examine the role of HA in synovial fluid. As suspected, the HA appears to have little impact on the actual aggregation process. Additionally, the relationship between the rheology and tribology of the SFM was studied through a series of nanoscratch tests using a Hysitron nanoindenter. The nanoindenter has the ability to measure both normal and lateral forces simultaneously, which gives an indication of the lubricity of the solution. The coefficient of friction values for solutions of varying protein concentrations were determined by dividing the lateral force by the normal force. Tribological testing of the synovial fluid model and modified solutions were carried out on spin-cast polyethylene and ultra high molecular weight polyethylene sheets. At lower molecular weight substrates, the film thickness limited the validity of the generated data, and with higher molecular weight surfaces, surface roughness effects were found to dominate the tribological response. Finally, the addition of HCQ does not have a large impact on the tribological data, indicating that the anti-inflammatory drug does not significantly impact the lubrication properties within the synovial fluid model. Finally, additional rheological studies of biopolymer solutions were conducted in which solutions containing chitosan, a natural, bioactive polymer, were characterized to determine their fitness for the electropsinning process. Chitosan fibers are difficult to electrospin, and through these studies, the entanglement concentration, a critical parameter for electrospinning, was determined. The generated rheological data provided a means to predict the morphology of the resulting nanofibers, and aspects of the difficulty in electrospinning chitosan were revealed.
Study of the rheological behavior of chocolate and margarine [abstract
Directory of Open Access Journals (Sweden)
Debaste, F.
Full Text Available In the food industry, the production process is often established in an empirical way, according to rules of good practice. These methods present gaps, in particular at the level of the production regularity. To model and optimize the processes, it is highly useful to determine the physico-chemical properties of the product. In this work, chocolate and margarine are studied, both aiming direct industrial application but also aiming a general enhancement of rheological mechanism understanding. Indeed, the chocolate is a suspension of solid particles in cocoa butter and the margarine is a water-in-oil emulsion. Rheological behavior of those fluids is therefore relying on different key phenomena. In this work the flow behavior of both products is characterized and a mathematical model describing the rheological behavior of chocolate is developed. For chocolate, the goal is to model the tempering process. To establish the rheological behavior of chocolate, viscosity measurements were realized in a SEARLE VT550 viscometer using a bob and cup geometry. To build the mathematical law, general tests following the International Office of Cocoa, Chocolate and Sugar Confectionery (IOCCC recommended method (Servais et al., 2004 were performed. The obtained rheogram shows that the chocolate has a slightly thixotropic behavior. More focus is set on a smaller range of shear rate important for the industrial application (Debaste et al., 2008. Measures for various temperatures and various quantities of cocoa butter were realized. The results show a classical shear-thinning behavior. Further, a statistical analysis of the results was made to determine the parameters of a power-law describing this behavior. It appears that temperature and cocoa butter fraction have no influence on the exponent but well on the consistency parameter. For margarine, the goal is to model the flow in resting tubes, the last step in the industrial production (Herman et al., 2008. To determine the rheological behavior of the margarine two kinds of devices were used. First the SEARLE VT550 viscometer with a four blades impeller was used. And the results were not satisfying because the measured viscosity was often nulls. We suppose that the sample was broken into two blocks, one between the blades of the impeller and a second outside of the impeller. A HAAK MARS rheometer with a plate-plate geometry was also used. In both experiments we evaluate how a change of 1�C can affect the viscosity of margarine. The obtained flow curves show that the margarine has a plastic and thixotropic behavior and that a variation of 1�C affects margarine's rheology. With the chocolate rheological law, the perspective is to get a general model for concentrated suspensions. And for margarine, more measures with an adapted viscometer should be done to build a model.
Flexible electrochromic windows: a comparison using liquid and solid electrolytes
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Girotto Emerson Marcelo
Full Text Available In the present work, two electrochromic devices (or electrochromic windows based on intrinsically conducting polymers were assembled and characterized. For both devices, the materials used on the assembling were the same except for the electrolyte layer. In the first, we used as electrolyte a propylene carbonate solution and in the second the elastomer poly(epichlorohydrin-co-ethylene oxide, both containing LiClO4. The conductivity of the liquid electrolyte (10-3 S cm-1 is approximately two orders of magnitude higher than for the solid electrolyte and we obtained very good electrochromic properties in both cases. The calculated electrochromic efficiency at 640 nm was 700 C cm-2 for the liquid electrolyte device and 360 C cm-2 for the solid state device. Solid state electrochromic windows have been investigated and some of its advantages over windows with liquid electrolytes are discussed.
Safer lithium ion batteries based on nonflammable electrolyte
Zeng, Ziqi; Wu, Bingbin; Xiao, Lifen; Jiang, Xiaoyu; Chen, Yao; Ai, Xinping; Yang, Hanxi; Cao, Yuliang
The safety of lithium ion batteries has long been a critical obstacle for their high-power and large-scale applications because of the flammable nature of their carbon anode and organic carbonate electrolytes. To eliminate the potential safety hazards, lithium ion batteries should be built up with thermal-stable electrodes and nonflammable electrolytes. Here we report safer lithium ion batteries using nonflammable phosphonate electrolyte, thermal-stable LiFePO4 cathode and alloy anodes. Benefiting from the electrochemical compatibility and strong fire-retardancy of the phosphonate electrolyte, the cathode and anode materials in the nonflammable phosphonate electrolyte demonstrate similar charge-discharge performances with those in the conventional carbonate electrolyte, showing a great prospect for large-scale applications in electric vehicles and grid-scale electric energy storage.
Electrode-Electrolyte Interfaces in Solid Polymer Lithium Batteries
Hu, Qichao
This thesis studies the performance of solid polymer lithium batteries from room temperature to elevated temperatures using mainly electrochemical techniques, with emphasis on the bulk properties of the polymer electrolyte and the electrode-electrolyte interfaces. Its contributions include: 1) Demonstrated the relationship between polymer segmental motion and ionic conductivity indeed has a Vogel-Tammann-Fulcher (VTF) dependence, and improved the conductivity of the graft copolymer electrolyt...
Flexible electrochromic windows: a comparison using liquid and solid electrolytes
Girotto Emerson Marcelo; De Paoli Marco-A.
In the present work, two electrochromic devices (or electrochromic windows) based on intrinsically conducting polymers were assembled and characterized. For both devices, the materials used on the assembling were the same except for the electrolyte layer. In the first, we used as electrolyte a propylene carbonate solution and in the second the elastomer poly(epichlorohydrin-co-ethylene oxide), both containing LiClO4. The conductivity of the liquid electrolyte (10-3 S cm-1) is approximately tw...