Neutron Scattering Study of the Vibration-Relaxation Crossover in Amorphous Polycarbonates

Abstract
We report on neutron scattering observations of the fast picosecond relaxation in two amorphous polycarbonates. Contrary to previous experience, one already observes these fast relaxations far below the glass transition, at temperatures where they cannot be related to the flow process. An explanation in terms of low-barrier structural relaxations is proposed.