Dynamics at the glass transition in polymers: results from neutron spectroscopy

摘要

This short review presents quasielastic neutron scattering and dielectric experiments on the alpha and beta _slow relaxation in polybutadiene and polyvinylchloride. Exploiting the momentum transfer dependent dynamic structure factor, spatial information about the underlying molecular motions is obtained. While the beta _slow process reveals itself as a local jump with average jump distancesof about 1.5 A, the alpha relaxation is diffusive and occurs statistically independently form the beta _slow process. With this result a consistent interpretation of dielectric spectra on the same polymer is achieved. Finally some new results on the alpha process in PVC are presented.