The role of lamellar morphology on the post-irradiation oxidative degradation of ultra-high molecular weight polyethylene

Post-irradiation oxidative degradation of ultra-high molecular weight polyethylene (UHMWPE) has drawn much attention due to the well-known effects of the long term-degradation of mechanical and wear properties after gamma-radiation induced sterilization of orthopedic implant components. While the chemistry of oxidation, associated morphological changes and consequence of the effects of post-gamma radiation aging on the properties of UHMWPE components have been extensively studied in both laboratory fabricated components and explants, there have been no systematic studies on the effects of the lamellar morphology of post-radiation aging of PE. In this study, high-pressure crystallization was used to produce UHMWPE with various degrees of crystallinity and lamellar thickness, subjected to the same 50 kGy dose of gamma radiation, accelerated aged and then subjected to Fourier Transform Infrared Spectroscopy which, combined with ultra-small angle x-ray scattering, was used to draw quantitative correlations between morphological parameters and oxidative degradation. Lamellar thickness was shown to monotonically increase post-radiation oxidation.