Correlation between the mechanical behavior and relaxation processes in the plastically deformed polycarbonate

Publisher Website
Google Scholar
Abstract
The low‐temperature β relaxation has been studied via thermally stimulated depolarization current (TSD) method for polycarbonate that had been cold‐rolled and subsequently undergone the α′ relaxation at 70°C as a function of time. It has been found that the intensity of the β process increased as the annealing at 70°C increased. The analysis of the activation energy spectrum associated with the β relaxation indicated that the enhancement in the β intensity was due to the liberation of local dipoles from their aligned orientation as a result of undergoing the α′ relaxation process. Tensile flow curves have also been determined for the same set of specimens. Similar enhancement was also observed in the yield stress behavior. In view of the good correlation between the mechanical property and the structural change revealed by the relaxation study, it was concluded that the variation of the yield stress and the work‐hardening in the rolled polymer was primarily associated with those parts of the chain that had been disoriented from their frozen‐in conformations.