Creep and recovery of ultra high modulus polyethylene

Abstract The creep and recovery behaviour of ultra high modulus polyethylene has been studied over the temperature range 20–70°C. Four types of material were examined; low molecular weight and intermediate molecular weight homopolymer, an ethylene hexene-1 copolymer, and a sample prepared by γ-irradiation of isotropic low molecular weight polymer prior to drawing. With the exception of the low molecular weight homopolymer, the materials showed an apparent critical stress below which there was no detectable permanent creep. It is proposed that the behaviour of all the materials can be described to a good approximation by a simple model, where two activated processes are coupled in parallel. Tentative structural explanations of the results are also given.

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