INVESTIGATIONS ON THE COLD CRYSTALLIZATION OF PURE AND FILLED PETP BY DIELECTRIC MEASUREMENTS

The cold crystallization of pure and filled poly (ethylene terephthalate) (PETP) after quenching from the melt has been investigated by dielectric measurements in two different modes: The first one using constant heating-rate (in the temperature range from 320 to 480 K) and the second one under isothermal conditions (at 378 K). The complex dielectric constant (epsilon', tan delta) is influenced by crystallization. Two alpha-relaxation regions are identified: The alpha(a)-relaxation region from the pure amorphous phase and the alpha'-relaxation region from the spherulitic phase. The investigations on the filled systems (PETP + 10% aramid pulpe, PETP + 30% short glass fibres) prove that an influence of the fillers on the time delay and rate of crystallization and on the geometry of the growing spherulites exists.