Oxidative degradation behavior of irradiated GO/UHMWPE nanocomposites immersed in simulated body fluid

In this study, the artificial joint substrate material of ultra-high molecular weight polyethylene (UHMWPE) is modified by irradiation cross-linking and graphene oxide (GO). The aim of the study is to evaluate the oxidative degradation behavior of GO/UHMWPE nanocomposites immersed in the simulated body fluid (SBF) atmosphere for a long term at 37 °C, using SBF absorption rate, Fourier transform infrared spectroscopy, electron spin resonance and ball indentation hardness. The results demonstrated that both methods of irradiation cross-linking and GO mixing can effectively improve the physicochemical properties and mechanical properties of UHMWPE matrix. After all the samples were immersed for 12 months, the value of ball indentation hardness of UHMWPE, R-UHMWPE, GO/UHMWPE and R-GO/UHMWPE was decreased by 19.6%, 23.18%, 34.58% and 31.88%, respectively. The GO/UHMWPE nanocomposites suffer from severe oxidative degradation compared to the original UHMWPE. Particularly, the pre-degradation rate was accelerated when mixed with GO. However, irradiated GO/UHMWPE (R-GO/UHMWPE) still exhibited optimal physical performance after oxidative degradation. This study highlights the importance of using more realistic solutions to characterize the performance of the modified UHMWPE nanocomposites, and reveals the mechanism of GO addition and irradiation cross-linking treatment on the UHMWPE nanocomposites immersed in SBF for a long time.