Influence of multi walled carbon nanotubes reinforcement and gamma irradiation on the wear behaviour of UHMWPE

Ultra high molecular weight polyethylene (UHMWPE) was reinforced by chemically treated multi walled carbon nanotubes (MWCNTs) up to 2.0 wt% and later subjected to gamma irradiation up to 100 kGy dose. The influence of MWCNTs on the hardness and wear resistance of UHMWPE was evaluated before and after the irradiation process. The hardness of UHMWPE was increased by 89% by homogeneous dispersion of 2 wt% MWCNTs and 100 kGy irradiation. Wear studies on the test samples revealed that the wear volume of unirradiated UHMWPE was reduced by 31%, 54% and 73% upon dispersing 2 wt% MWCNTs, 100 kGy irradiation and the combination of both, respectively. The surface morphology and topography of the wear tracks were examined to understand the wear mechanisms of UHMWPE and its composites. Though the wear mechanism observed in the polymer and composites under normal and irradiated condition is found to be the same, the severity of wear was found to be reduced for irradiated composites compared to unirradiated UHMWPE. The crosslink density (CLD) of composites was found to be higher than that of UHMWPE. It is concluded that the cumulative effect of the presence of MWCNTs and irradiation effectively increased the wear resistance of UHMWPE.