Slow relaxations in semicrystalline poly(butylene succinate) below and aboveTg

Abstract

The slow molecular mobility in the amorphous part of the semi-crystalline polymer poly(butylene succinate) (PBS) has been studied by the thermally stimulated depolarization current (TSDC) technique. Experiments were carried out in the temperature range, which includes the glassy state, the glass transformation region, and the rubber state. A broad and low intensity secondary relaxation was observed in the temperature region from −140°C up to the glass transition region; the activation energy of the motional modes of this secondary relaxation was in the range between 35 and 55 kJ mol−1. The glass transition temperature of PBS, provided by the TSDC technique, was Tg = −40 °C, and the fragility index was found to be m = 43. The aging behavior of the main and of the secondary relaxations was analyzed. A strong relaxation above Tg was observed, whose molecular origin was discussed. The thermal behavior of the PBS was also characterized by differential scanning calorimetry. POLYM. ENG. SCI., 55:1873–1880, 2015. © 2014 Society of Plastics Engineers