BOSON PEAK AND FAST RELAXATION PROCESS NEAR THE GLASS-TRANSITION IN POLYSTYRENE

Atactic polystyrene, both side group and main chain deuterated, was investigated by inelastic neutron scattering in a wide temperature range around the glass transition from 2 to 450 K. In the glass the Boson peak position is only very weakly influenced by the deuteration of the phenyl group. In the neighborhood of the glass transition temperature T-g we find a fast relaxation process similar to other glasses. The onset of the fast relaxation in polystyrene, however, is observed already at temperatures T-g - 200 K. Results from partially deuterated polystyrene suggest a change of the phenyl ring dynamics already far below T-g.