The Effects of Molecular Structure on Polymer Viscoelastic  Flow Functions in Steady and Time Dependent Simple Shearing Flow
{'Code': '07020000', 'Directorate': {'Abbreviation': 'ENG', 'LongName': 'Directorate For Engineering'}, 'Division': {'Abbreviation': 'CBET', 'LongName': 'Div Of Chem, Bioeng, Env, & Transp Sys'}}
{'SignBlockName': 'Robert M. Wellek', 'PO_EMAI': None, 'PO_PHON': None}
Research Summary:  Flow function data for systematic variations                 in well-characterized polymer structures for a variety of                       shearing modes are critically needed for the development and                    evaluation of constitutive equations relating viscoelastic flow                 functions to polymer structure.  The effect on the flow functions               of molecular weight,  weight distribution, stiffness, and                       complexity will be determined for linear polymers.  Additionally,               for branched polymers, the effects of branch number, length, and                uniformity for star polymers, and branch distribution for comb                  and randomly branched polymers will be determined.  The flow                    functions will include the viscosity, and especially the first                  and second normal stress differences, N1 and N2, and derived                    functions in steady shearing, oscillatory, stress growth and                    relaxation, and step strain deformations.  Low compliance                       Weissenberg and Rheometries rheometers will be used in cone-plate               and parallel plate shearing.  Modification of constitutive                      equations, especially relaxation functions, will be studied.                                                                                                    Technical Impact/Practical Applications:  The complete flow                     function data will provide a basis for the formulation of                       realistic constitutive equations for use with the transport                     equations in the design of polymer production and processing                    equipment.  Some applications follow:  Extrudate Swell.  The                    control of extrudate swell is critically important in such                      operations as the extrusion of plastic pipe, rods, and plastic                  vessel parisons.  The rarely available ratio of N2 to N1 has been               shown to be a major factor in extrudate swell.  The proposed                    research will generate the required high shear-rate data and                    instrumentation to acquire such data.  Wire Coating.  Second                    normal stress difference and fluid dynamic forces act to center                 the wire in a coating of plastic.  Dies designed to utilize these               forces could reduce the average coating thickness, meet thickness               specifications, and reduce material costs.  The instrumentation                 developed by this proposal will make possible for the first time                the acquirement of the required high shear-rate  N2 data.  Shaft                Climbing on the shafts of mixers and reactors in the food and polymers          or plastics industries must be managed. In one case, polymers climbed           up the shaft and into the drive of a large mixer and forced a costly            shutdown.  With a knowledge of the ratio of N2 to N1 (currently rarely          available), rod climbing can be predicted and mixers can be designed            to avert the problems.  Reverse Flow.  In stirred tank polymer and              biological reactors and mixers, significant normal stresses cause               radially inward flow towards the mixer shafts (vs. radially outward).           Mass and heat transfer and efficiency are importantly reduced by                major changes in flow patterns.  With a knowlege of the ratio of                N2 to N1, reverse flow can be predicted and design measures taken               to improve performance.
{'FirstName': 'K.', 'LastName': 'DeVries', 'PI_MID_INIT': 'L', 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'K. L DeVries', 'EmailAddress': 'larry.devries@dean.eng.utah.edu', 'NSF_ID': '000423790', 'StartDate': '04/01/1987', 'EndDate': None, 'RoleCode': 'Principal Investigator'}
{'Name': 'University of Utah', 'CityName': 'SALT LAKE CITY', 'ZipCode': '841129049', 'PhoneNumber': '8015816903', 'StreetAddress': '201 PRESIDENTS CIR', 'StreetAddress2': None, 'CountryName': 'United States', 'StateName': 'Utah', 'StateCode': 'UT', 'CONGRESSDISTRICT': '01', 'CONGRESS_DISTRICT_ORG': 'UT01', 'ORG_UEI_NUM': 'LL8GLEVH6MG3', 'ORG_LGL_BUS_NAME': 'UNIVERSITY OF UTAH', 'ORG_PRNT_UEI_NUM': None}
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{'Code': '1414', 'Text': 'INTERFAC PROCESSES & THERMODYN'}
{'url': 'https://www.nsf.gov/awardsearch/download?DownloadFileName=1986&All=true', 'xml': '8616542.xml'}