Relaxations versus crosslink density in glass- and gel-forming polyurethane

Abstract

An experimental investigation of the relaxational processes related to the glass transition is presented in polymers where the crosslink density can be varied. This study is an extension of previous measurements to higher frequencies. We used inelastic light and neutron scattering to determine the relaxation times in the 10 −8−10 −12 s range. The relaxation time determined from neutron backscattering exhibits a Q −3.7 dependence, as already found for the α process in other glass-forming systems. The time measured by Brillouin scattering splits from the structural relaxation time.