Wear behavior of medical grade PEEK and CFR PEEK under dry and bovine serum conditions

Wear is among the main factors affecting the performance of artificial couplings in joint arthroplasty. In the attempt of investigating the applicability of PEEK and CFR PEEK in such applications, wear behavior of three medical grade PEEK formulations (unfilled PEEK, 30% wt. pitch carbon fibre reinforced PEEK and 30% wt. PAN carbon fibre reinforced PEEK) have been tested under dry and bovine serum lubricated conditions in a pin on flat test against Al2O3 1/8” spheres, replicating physiological conditions whereas possible. The crystallinity and the resulting mechanical properties of the three selected material were differentiated by annealing treatments performed at 200, 250, and 300°C. All the specimens were tested under both lubrication regimes. The observed coefficient of friction variations, as well as the calculated volumetric wear rate, displayed an improved wear behavior of the reinforced formulations in both dry and bovine serum. Correlation among the modified material properties by annealing and the wear behavior was possible. The formation of a lubricating film was identified as responsible for an improved wear performance of PEEK and CFR PEEK formulations.