Experiments on the Internal Structure of Latexes Using SmallAngle Neutron Scattering
{'Code': '07020000', 'Directorate': {'Abbreviation': 'ENG', 'LongName': 'Directorate For Engineering'}, 'Division': {'Abbreviation': 'CBET', 'LongName': 'Div Of Chem, Bioeng, Env, & Transp Sys'}}
{'SignBlockName': 'Maria Burka'}
The purpose of this research is to obtain basic information about the           kinetics of formation and how these kinetics affect the final                   structure of latex particles.  These materials are used as coatings             and paints, also as impact modifiers.  The value of this work to                modern industry is that with an improved understanding of the                   structure and behavior of latex particles, better materials can be              produced.  Questions relating to film formation kinetics, strength of           materials, and  special purpose applications including medicine and             biotechnology depend on a detailed knowledge of the structure and               behavior of the latexes.                                                                                                                                        Structured latexes are submicron sized particles, with some unique              internal morphology, suspended in a fluid medium, most often water.             When the dimensions of the chains are about half those of the latex             diameter, some type of segregation is present, with the first                   polymerized material appearing near the center of the particle.                 Technologically, the most significant structured latex is the                   core-shell type with a rubbery core and a glassy shell.  This type              generically represents high-impact polymers, and more specifically ABS          (acrylonitrile-butadiene-styrene) plastics and acrylic impact                   modifiers.                                                                                                                                                      The PIs plan to look at both homopolymer and copolymer latexes                  using small-angle neutron scattering (SAS) to follow the course of the          polymerization.  To elucidate homopolymer structure, polystyrene will           be used.  They plan to test the hypothesis that polystyrene of                  molecular dimension about half of the latex particle size segregates            into what appears to be a core and a shell, with the first polymerized          chains tending to be near the center of the particle.  The question of          how much segregation exists before the second portion of the monomer            is polymerized, and how the extent of segregation changes during                polymerization, will be the subject of planned experiments.  The model          assumes that the internal viscosity of the system is high, and/or               vitrification is occurring, the final system being below its glass              transition temperature, and the polymer soluble in the monomer.                                                                                                 To look at copolymer systems, small-angle neutron scattering                    measurements will be made before polymerization of the second                   component is initiated, and several times during the                            polymerization.  The results should elucidate if segregation                    occurs or, if not the rate of desegregation decrease as the                     internal viscosity of the system increases and/or if the glass                  transition of monomer-plasticized particles is approached.
[{'FirstName': 'Andrew', 'LastName': 'Klein', 'EmailAddress': 'ak04@lehigh.edu', 'StartDate': '03/15/1989', 'EndDate': None, 'RoleCode': 'Co-Principal Investigator'}, {'FirstName': 'Leslie', 'LastName': 'Sperling', 'EmailAddress': 'lhs0@lehigh.edu', 'StartDate': '03/15/1989', 'EndDate': None, 'RoleCode': 'Principal Investigator'}]
{'Name': 'Lehigh University', 'CityName': 'Bethlehem', 'ZipCode': '180153005', 'PhoneNumber': '6107583021', 'StreetAddress': 'Alumni Building 27', 'CountryName': 'United States', 'StateName': 'Pennsylvania', 'StateCode': 'PA'}
{'Code': '1403', 'Text': 'Proc Sys, Reac Eng & Mol Therm'}
{'url': 'https://www.nsf.gov/awardsearch/download?DownloadFileName=1988&All=true', 'xml': '8820705.xml'}