COHERENT QUASI-ELASTIC SCATTERING FROM INTERNAL RELAXATIONS IN POLYMERS

The local dynamics of 1,4 polybutadiene below and above the merging of the alpha- and beta-relaxations have been investigated by means of Ne utron Spin Echo. At temperatures below the merging, the dynamic struct ure factor can be described by considering localized motions on a leng th scale of 1.5 Angstrom for the beta-process with the barrier distrib ution obtained from dielectric spectroscopy. Above the merging of the alpha- and beta-relaxations, the experimental data have been successfu lly described by assuming that both processes are statistically indepe ndent.