Production and characterization of ultra high molecular weight polyethylene (Uhmwpe) composites with reduced graphene oxide (Rgoc) using vitamin c

Ultra high molecular weight polyethylene (UHMWPE) has been broadly utilized in hip and knee artificial implants due to its low friction coefficient, high wear resistance and good biocompatibility. However some disadvantages such as its low Young's modulus, low load bearing and anti-fatigue capacity limit application areas and wear debris of UHMWPE components also, cause implant failure. For this reason, reduced graphene oxide (RGOC) filler that was reduced using vitamin C was used as filler for the UHMWPE matrix to produce composite materials possessing advanced properties especially against wear. UHMWPE composites filled with different loading (0.1, 0.3, 1.0 and 2.0 wt.%) of RGOC were fabricated by firstly liquid phase ultrasonic mixing and then hot press molding to investigate microstructural and tribological properties. The wear and friction behavior of composites were investigated in sliding against an Al2O3 counterface and experiments carried out in a reciprocating friction testing machine under dry, distilled water, serum and Hank's solutions lubricating conditions. The microstructural analysis results of composites showed that RGOC well-dispersed in polymer matrix and confirmed that there was interaction between the RGOC and UHMWPE. UHMWPE/RGOC composites exhibited the lowest friction coefficient under distilled water lubricating condition than serum and Hank's solutions conditions, due to the lubricating effect of both distilled water and RGOC. But the lowest wear rate values of composites were found in the serum and Hank's lubrication conditions because the wettability of composites in these solutions was better than that of distilled water and dry sliding conditions. Furthermore, fatigue wear tracks were significantly reduced when RGOC was added in the polymer matrix at all lubrication conditions. Composite with 1.0 wt.% RGOC had high hardness, the highest crystallinity and the least wear debris resulting in the lowest friction coefficient and wear rate under all lubricating conditions. This study suggests the use of this composite that had excellent tribological behaviour as biomaterial instead of UHMWPE.