Influence of SBF-induced degradation on surface and tribological properties of irradiated GO/UHMWPE nanocomposites

As a well-known biomaterial, ultra-high molecular weight polyethylene (UHMWPE) has been widely used as a substrate of artificial joints, due to its excellent biocompatibility, mechanical properties and anti-wear properties. In this work, graphene oxide (GO) and irradiation cross-linking are applied to enhance the performance of UHMWPE matrix, and then GO/UHMWPE nanocomposites were immersed in simulated body fluid (SBF) at 37 ℃ for 6 months to simulate the service environment of human body. The results showed that irradiation cross-linking treatment will promote the break and recombination of the molecular chains of UHMWPE and GO. The addition of GO which is followed by irradiation cross-linking method can increase the crystallinity and melting point, meanwhile, lead to a decrement in the friction coefficient and wear rate of the substrate. The average friction coefficient and wear rate were decreased to 0.1035 and 4.78 × 10–9 g N−1 m−1 under the simultaneous function of irradiation cross-linking and GO addition. However, after immersion in SBF for 6 months, their crystallinity, friction coefficient and wear rate were increased, resulting from the swelling reaction on the surface of GO/UHMWPE nanocomposites. In conclusion, the cross-linking by irradiation and GO addition were utilized to synergistically enhance the surface and tribological properties of UHMWPE substrate, which further verifies that it is an effective method to lower the degradation of UHMWPE in SBF. The swelling reaction and anti-wear mechanism were also revealed in this work.