Tracing the antioxidant effect of vitamin E on ultra-high molecular weight polyethylene

The antioxidant effect of vitamin E on ultra-high molecular weight polyethylene (UHMWPE) during radiation oxidation and post-irradiation oxidation process was investigated using electron paramagnetic resonance spectroscopy (EPR) and fourier transform infrared microscopy (FTIR). EPR results showed that the free radical concentration of UHMWPE induced by γ-rays irradiation decreased with increasing vitamin E content both in air and nitrogen atmosphere. FTIR results indicated that the irradiated samples underwent a continuous oxidation reaction, and the higher the vitamin E content, the lower the oxidation reaction. However, radiation oxidation also occurred inevitably to the vitamin E-stabilized UHMWPE indicating vitamin E could only partially prevent oxidation. Further investigation suggested that ozone can rapidly oxidize the vitamin E-stabilized UHMWPE, that is, vitamin E cannot prevent ozone from oxidizing UHMWPE. Then radiation oxidation schematic presentation of vitamin E-stabilized UHMWPE was described. This work would provide more comprehensive understanding on the radiation oxidation and post-irradiation oxidation of vitamin E-stabilized UHMWPE.