HIGH MODULUS POLYETHYLENE FIBERS BY ZONE-DRAWING METHOD IN THE PRESENCE OF OSCILLATORY STRESS

EFFECT OF DRAW RATIO ON MECHANICAL PROPERTIES AND MOLECULAR ORIENTATION

Abstract

Super-drawn polyethylene filaments were produced by a zone-drawing method with oscillatory stress in the range of the crystalline relaxation temperature. Resultant fibers showed transparence, homogeneous diameter and smooth fiber surface. Good linear relationship was obtained between the reciprocal of Young's modulus and that of draw ratio squared (1/λ²). Plots of birefringence against 1/λ² were also fitted well with a straight line. Orientation of the tie molecules in the amorphous state is responsible for large increase in Young's modulus. The average molecular orientation angle of the tie molecules was also found to be proportional to 1 /λ². This orientation behavior during drawing process may suggest that tie molecules can be deformed to the drawing direction but not perpendicular to it.