Morphological studies of cold drawn poly(ethylene terephthalate)

Abstract

Morphology of cold drawn poly(ethylene terephthalate) (PET) was studied by the X-ray diffraction method. In slowly drawn PET, paracrystalline reflections were observed at an early stage of crystallization by annealing, and it was found that the paracrystalline structure was basically monoclinic. In the case of annealing at temperatures below 100°C, the crystalline structure became triclinic after passing through the paracrystalline state. Tilting of the crystalline c-axis (molecular axis) was seen in the course of the transition from the paracrystalline to the triclinic state. At higher annealing temperatures, the triclinic crystallites were sufficiently developed to form crystalline layers in which the molecular chains were tilted in directions which depended on the inclination of the layers.In the case of rapid drawing, strain-induced crystallization occurred, but paracrystalline reflections were not observed. In the rapidly drawn sample, tilt of the c-axis was small, while inclination of the layer was large. © 1973, The Society of Polymer Science, Japan. All rights reserved.