Ageing of UHMWPE in presence of simulated synovial fluid

Abstract

In this paper, the biomedical grade Ultra High Molecular Weight Polyethylene (UHMWPE) has been soaked at different temperatures in Simulated Synovial Fluid (SSF); diffusion coefficient, hardness, roughness and wettability has been evaluated. Then, the 37°C (body temperature) soaked-polyethylene sample was aged at 80°C and monitored by InfraRed spectroscopy (oxidation trackers) and GPC (for molar mass changes) to observe the long-term degrading action of SSF. Finally, a kinetic model has been performed to simulate the ageing. Results highlighted as SFF smooths the material's surface, diffusing within the polymer helped by the temperature growth. The oxidation kinetic study stated that PE is more degraded by SSF with a significant decrease of molecular weight of a factor 2 if helped by the ageing temperature of 80°C. Simulation models are effective to theoretically reproduce pro-degradation mechanisms induced by SSF on UHMWPE at 80°C.