Effect of radiation dose on depth-dependent oxidation and wear of shelf-aged gamma-irradiated ultra-high molecular weight polyethylene (UHMWPE)

The effect of radiation dose on the depth-dependent oxidation and wear of shelf-aged gamma-irradiated UHMWPE was investigated in this paper. FTIR, micro-indentation, pin-on-plate wear tests and SEM imaging were carried out at three representative regions (surface, subsurface and center) for each sample. The experimental results show that when the oxidation index (OI) <1, the wear rate is clearly affected by the radiation dose (crosslinking density). When 1<OI<3, the wear rates are mainly controlled by the OI. When OI>3 - except for the 1000 kGy specimen - the wear resistance is severely deteriorated and the relationship with the radiation dose is difficult to predict. Results suggest that higher irradiation (above 200 kGy) is capable of lowering the oxidative degradation of UHMWPE.