The Preparation and Study on Ultrahigh Molecular Weight Polypropylene Gel‐spun Fibers

Abstract

A novel polypropylene (PP) fiber was prepared by using gel spinning/crystallization from dilute solutions of ultrahigh molecular weight isotactic polypropylene (i‐UHMWPP), and subsequently drawing at various temperatures. The influence of drawing temperature on the properties of the resulted fibers was investigated. We found that the draw‐ability and mechanical as well as crystallization properties of the fibers obtained were dramatically improved with increasing drawing temperature. When the drawing temperature is below the α‐crystal relaxation temperature of PP, which was measured by wide‐angle X‐ray diffraction (WAXD) analysis as 100–120°C, the fibers are characterized by lower crystallinity and smaller crystals with less perfection, resulting in brittle fracture and subsequently poor mechanical durability. With drawing at temperatures above the α‐crystal relaxation temperature of PP, a novel UHMWPP fiber with Young's modulus of 27 GPa and tensile strength of 1.3 GPa was obtained. Higher crystallinity and larger crystals with better perfection and orientation were observed in this fiber.