Annealing of gel-spun hot-drawn ultra-high molecular weight polyethylene fibres

Summary Gel-spun hot-drawn ultra-high molecular weight polyethylene (UHMWPE) fibres were annealed with fixed fibre ends, at temperatures near the orthorhombic-hexagonal lattice transition temperature. A permanently reduced tensile modulus without loss in tensile strength, i.e. increased elongation at break, was observed upon tensile testing of these annealed fibres. The uncharged tensile strength upon annealing, indicates that the tensile strength is likely to be determined by the entanglement concentration.