CRYSTALLIZATION OF ORIENTED PET YARN——Spontaneous Extension of Oriented PET Yarn in Crystallization

摘要

This paper presents a method to measure the spontaneous extension of oriented PET fibredirectly during crystallization by twice annealing (constant-length and free-length). Samples be-fore and after the treatment were collected and examined by X-ray diffraction, DSC andbirefringence. The crystallinity, crystallite size, and orientation of both crystalline and amorphousparts between these samples are changed greatly which show that the extension is a consequence ofcrystallization and reorientation of uncrystallized segments along the fibre direction. The results ofthis study are not only important to understand the mechanism of supermolecular structurechanges during crystallization, but also useful to the industrial technology of crystallization spin-ning.