Gel-spun polyethylene fibres. Part 1. Influence of spinning temperature and spinline stretching on morphology and properties

摘要

The tensile strength of gel-spun polyethylene fibres hot-drawn to the maximum draw ratio depends on the spinning conditions such as spinning speed, spinline draw ratio and spinning temperature. High deformation rates during spinning introduce defects and fibres with poor ultimate properties are produced. These defects are already present before the hot-drawing step and can be detected indirectly by wide-angle X-ray scattering, since they are accompanied by preferential c-axis orientation parallel to the fibre axis and a shish-kebab structure. The introduction of flaws such as chain scission and tight knots can be prevented by avoiding spinline stretching and/or increasing the spinning temperature. This is due to the fact that higher spinning temperatures reduce the span of time in which the chains remain entangled and behave like a real network. Due to their lamellar/shish-kebab structure, the extracted fibres show a mechanical behaviour which to some extent is characteristic of composites.