A detailed TSD-study of the glass transition region of amorphous polymers

The glass-transition region of amorphous polyvinylacetate was investigated by means of thermally stimulated depolarization currents (TSDs). The thermal-sampling (TS) technique was applied to analyze the TSD alpha -peak in more detail. Structural relaxation which is the origin of physical aging affects the TSD alpha -peaks and the TS peaks of the glass-transition region strongly. This influence was taken into account by variation of the cooling and heating rates and by variation of annealing time at different temperatures near glass transition. Besides the collective processes of molecular motion, there are relaxation processes connected with local conformational changes which influence the low-temperature tail of the TSD alpha -peak. >