| Abstract
| - Molecular dynamics (MD) simulations of bulk atactic polystyrene have been performed forchains up to 320 monomer units in a temperature range from 100 to 600 K and in a broad pressurerange from 0.1 to 1000 MPa. The MD-determined specific volume vs temperature curves are in a goodagreement with experimental PVT data at different values of applied pressure, but the measured glass-transition temperature, Tg, is displaced to somewhat higher temperature than the longer time experimentalvalue. Local translational mobility has been investigated by measuring the mean-square translationaldisplacements of monomers as a function of time. The long-time asymptotic slope of these dependenciesis close to 0.6 at T > Tg, showing diffusive behavior. The cage effect, when local translational motions areessentially frozen in the glassy state, has been studied. The characteristic time of cage release does notdepend on molecular weight, but the duration of the crossover to the diffusive regime increases almostlinearly with increasing chain molecular weight, for both the backbone monomers and phenyl side groups.
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