Abstract
The mechanical and oxidative performance of dl-α-tocopherol (vitamin E, VE) blended Ultrahigh Molecular Weight Polyethylene (UHMWPE) exposed to varying levels of electron-beam radiation was evaluated using hip simulator testing, FT-IR spectroscopy, gel-fraction analysis, differential scanning calorimetry, and tensile testing. Gel fraction values for the irradiated samples increased with the radiation dose, but decreased with higher concentrations of vitamin E. However, for higher doses of electron-beam radiation, the effect of vitamin E concentration was reduced, and increased gel fraction values were observed. The gel fraction values and hip simulator wear resistance values for a 0.3% (w/w) vitamin E blended UHMWPE sample irradiated with 300 kGy were equal to that for commercially available, highly-crosslinked UHMWPE. In addition, no significant changes in oxidation index, crystallinity, tensile strength or elongation-at-break were observed for the 300 kGy irradiated, 0.3% (w/w) vitamin E blended UHMWPE following oxidative ageing (ASTM F2003). Losses in elongation-at-break values were observed for samples receiving increased radiation doses, with higher vitamin E concentrations helping to attenuate these losses. However, for samples receiving 300 kGy of radiation, even the 1.0% vitamin E blended sample experienced a significant loss in elongation-at-break compared with its non-irradiated counterparts.
