Effect of Drawing of Poly(ethylene Terephthalate) Fiber on Molecular Orientation

Abstract

Polyester continuous filament yams were drawn at 36 and 200°C at four different draw ratios: 2.65, 3.0, 4.0, and 5.0. Crystallinity and molecular orientation were investigated using infrared spectroscopy, x-ray diffraction, birefringence, and sonic velocity. The densities were determined using the flotation technique, and sonic velocity was measured using a dynamic modulus tester PPM-5R. X-ray and infrared crystallinity indices of fibers changed because of the drawing, which could be further correlated with the data obtained by density measurement. Dyeing behavior was also investigated in terms of crystallinity changes caused by the thermomechanical process, and the changes in the molecular orientation because of drawing.