Uniaxial orientation and crystallization behavior of amorphous poly(ethylene terephthalate) fibers

摘要

The effects of drawing conditions on the orientation and crystallinity of poly(ethylene terephthalate) (PET) fibers were investigated by using optical birefringence, sonic velocity, and wide-angle X-ray diffraction measurements, respectively. The preferred condition for preparation of uniaxially oriented amorphous PET fibers was suggested. The crystallization behavior of oriented PET fibers under relaxed and fixed length conditions was investigated by using differential scanning calorimetry (DSC). The multi-overlapping peaks were observed in the non-isothermal DSC curves of oriented PET fibers under relaxed condition. The kinetics of non-isothermal crystallization of oriented PET fibers under relaxed condition was analyzed by using an equation which takes the multi-crystallization processes into account. The kinetic parameters of every process were obtained and the crystallization mechanism was discussed. The crystallization behavior under fixed length condition differs from that under relaxed condition.