Mechanical properties of ultra-high molecular weight polyethylene fibres in relation to structural changes and chain scissioning upon spinning and hot-drawing

Gel- and suspension-spun fibres of ultra-high molecular weight polyethylene have been subjected to hot-drawing at 148° C. It has been found that for these fibres and drawing conditions, strength and modulus are uniquely determined by the draw ratio, analogous to observations by Capaccio et al. [1] for melt-spun fibres. Draw ratios of 100 could be achieved, leading to a tensile strength at break of 3.8 GPa and a Young's modulus of 120 GPa. Chain scissioning occurs both in spinning and hot-drawing. There seems to be a limiting molecular weight of approximately 1.5×106. Extraction of the low molecular weight polyethylene from the as-spun fibres by controlled swelling, whereby an entanglement network of only the very long chains remains, substantially reduced the drawability of the fibres and only a draw ratio of 40 and a tensile strength of 1.7 GPa could be attained for such filaments