Effect of zone drawing on the structure and properties of melt-spun poly(trimethylene terephthalate) fiber

Melt-spun poly(trimethylene terephthalate) (PTT) fibers were zone-drawn and the structures and properties of the fibers were investigated in considera tion of the spinning and zone-drawing conditions. The draw ratio increased up to 4 with increasing drawing temperature to 180 degreesC, at a maximum d rawing stress of 220 MPa. Higher take-up velocity gave lower drawability of the fiber. The PTT fiber taken up at 4000 rpm was hardly drawn, in spite o f using maximum drawing stress, because a high degree of orientation had be en achieved in the spinning procedure. However, an additional enhancement o f birefringence was observed, indicating a further orientation of PTT molec ules by zone drawing. The exotherm peak at 60 degreesC disappeared and was shifted to a lower temperature with an increase in the take-up velocity, wh ich means that the orientation and crystallinity of the fiber increased. Th e d-spacing of (002) plane increased with increasing take-up velocity and d raw ratio, whereas those of (010) and (001) planes decreased. In all cases, the crystal size increased with take-up velocity and draw ratio. The cold- drawn PTT fiber revealed a kink band structure, which disappeared as the dr awing temperature was raised. The physical properties of zone-drawn PTT fib ers were improved as the draw ratio and take-up velocity increased. (C) 200 1 John Wiley & Sons, Inc.