EFFECTS OF MOLECULAR WEIGHT AND MOLECULAR WEIGHT DISTRIBUTION ON STRETCHABILITY OF POLYPROPYLENE FIBER

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Other Title
  • ポリプロピレン繊維の延伸性に及ぼす分子量と分子量分布の影響
  • (PART I) DEPENDENCE OF MAXIMUM DRAW RATIO ON MOLECULAR WEIGHT AND ITS DISTRIBUTION
  • 第1報　最高延伸倍率の分子量,分子量分布依存性

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Description

Effects of molecular weight and its distribution on stretchability of polypropylene fibers were studied in the temperature range between a room temperature and 140°C using undrawn filaments having molecnlar weights (MW) _??_=3.2×104_??_56.0×104 melt spun from fractions, thermally degradated, and unfractionated samples at spinning draft 50 (diameter and length of straight die used, 0.45mm and 0.5mm, respectively, the rate of output 0.765 cc/min, winding velocity 250m/min), at the optimum spinning temperature corresponding to molecular weight of each sample. Drawing was carried out at a fixed temperature with velocity 10cm/min in an oil bath by using the hand-drawing apparatus. The maximum draw ratio (MDR) is used as a parameter of stretchability, where MDR is defined as the draw ratio at which three-quarters of total filaments (20 filaments) brokes. The optimum draw temperature at which MDR is maximum is raised slightly with MW, however the temperature dependence of stretchability decreases with increased MW. Above 135°C, slretchability of filaments abruptly decreases except where filments have MW larger than 30.6×104. The increase in MDR of filament with draw temperature is attributed to the greater deformability of the whole crystalline region, which is suggested by the temperature dispersion of mechanical loss or thermal stress of filaments. Strechability of the sample having an extremely broad molecular weight distribution (MWD) (in this cnse, _??_=28) becomes larger than that having narrower MWD at temperatures lower than 100°C., and at temperatures above 100°C, however this tendency reverses. (MDR)max becomes maximum at _??_=5.4×104, which suggest that stretchability of filament is clogely related to the draining or disentanglement of the draining or disentanglement of the entangled chains in undrawn filaments.

Journal

  • Sen'i Gakkaishi

    Sen'i Gakkaishi 23 (2), 86-92, 1967

    The Society of Fiber Science and Technology, Japan

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