Dielectric relaxation study of poly (ether imide) by thermally stimulated depolarization currents

Abstract

This work presents a detailed study, by thermostimulated depolarization currents, of the molecular mobility of poly (ether imide) in a broad temperature range covering the amorphous solid state, the glass transition, and the rubber state. Taking advantage of the very wide distribution of motional modes of the PEI glass transition (the broadest of all known glass formers), we carried out an in-depth study of physical aging involving different modes, which provided a more comprehensive view of the aging process. We also analyzed in detail the mobility below T g where, in addition to the fast secondary relaxation, we identified a Johari-Goldstein. In the rubber state, on the other hand, we detected a mobility but showed that it corresponds to space charge motions rather to dipolar reorientations.