Effect of gamma irradiation on the ductile-to-brittle transition in ultra-high molecular weight polyethylene

Ultra-high molecular weight polyethylene (UHMWPE) is used in the manufacture of medical applications due to its excellent mechanical properties, abrasion resistance and biocompatibility. The products are usually sterilized by gamma radiation. It is well known that gamma irradiation introduces structural changes that may be detrimental to the integrity and performance of the polymer, limiting its useful life. Therefore, it is imperative to have a fundamental understanding of the fracture behaviour of the material. A commercial general grade ultra-high molecular weight polyethylene (UHMWPE) was irradiated with several total doses and the effects of gamma radiation on the mechanical behaviour of the polymer and its morphology were evaluated by tensile tests, electron spin resonance spectroscopy (ESR) and scanning electron microscopy (SEM). The experimental data show that the gamma irradiation changes the molecular structure of UHMWPE, degrades its tensile properties and produces a gradual ductile-to-brittle transition. (C) 2003 Elsevier Ltd. All rights reserved.