Uniaxial drawing behavior of syndiotactic polystyrene

The drawing behavior of syndiotactic polystyrene (sPS) has been studied in the temperature range around its glass transition. Amorphous sheets have be en prepared by quenching, and drawn at temperatures from 90-120 degrees C. The development of orientation and crystallization has been examined using the optical birefringence method, standard thermal analysis, and X-ray diff raction. The effect of draw ratio, draw rate, and draw temperature on orien tation and crystallinity were examined. Deformation dependent crystallizati on and orientation have been observed. Both orientation and crystallinity i ncrease with increasing draw ratio and draw rate, but decrease with increas ing draw temperature in the temperature range of 90-114 degrees C. These re sults can be explained according to the competition between deformation and relaxation of molecular chains during drawing. Results show that crystalli zation of sPS is predominantly controlled by stress rather than by temperat ure during drawing in the temperature range of 90-114 degrees C. (C) 1999 E lsevier Science Ltd. All rights reserved.