Short-Range Order in Polymer Liquids and Glasses

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The prior study by the principal investgator indicates the importance of short-range order in determining the properties of polymer glasses. To confirm this and obtain further information about the short-range order in polymer liquids and glasses, the following three lines of approach will be pursued. First, the investgator will perform X-ray scattering measurements on glassy polymer samples subject to different mechanical and thermal histories. He will empoly the technique of the intermediate- angle scattering measurement he had developed earlier, as well as the technique of energy-dispersive X-ray diffraction. Second, he will perform neutron-scattering measurement with four types of polystyrene - - ordinary polystyrene, perdeuteriated polystyrene, polystyrene deuteriated on aliphatic groups only, and polystyrene deuteriated on aromatic rings only. The results can provide more detailed information about the types of atomic pairs responsible for the short-rang order present. Third, molecular dynamics simulation of models of realistic bulk polystyrene will be performed and the result will be analyzed to aid the interpretation of the X-ray and neutron-scattering results.