Mechanical and Tribological Properties of Zeolite-reinforced UHMWPE Composite for Implant Application

Ultra-high molecular weight polyethylene (UHMWPE) reinforced with different loadings of zeolite particles were prepared using hot compression molding. The effects of zeolite particles on the mechanical and tribological properties of the UHMWPE composites were studied. The tribological properties were investigated using a Ducom TR-20 pin-on-disc tester under different sliding speeds of 0.209 m/s, 0.419 m/s and 0.838 m/s with various applied loads of 10, 20, and 30 N. The worn surfaces and transfer films of the zeolite/UHMWPE composites were observed under the scanning electron microscope (SEM). The results showed that the addition of zeolite into UHMWPE matrix has reduced the tensile strength and elongation at break, but increased the modulus. The 10 wt.% zeolite/UHMWPE composites showed an increase of similar to 25% in impact strength as compared to pure UHMWPE. The 20 wt.% zeolite/UHMWPE composite exhibited lowest wear volume loss as compared to 10 wt.% zeolite/UHMWPE and pure UHMWPE. In addition, the average coefficient of friction (COF) was also found to decrease with the addition of zeolite. The lowest average COF was also obtained with the 20 wt.% zeolite/UHMWPE composite. The wear volume loss was found to increase with increasing applied loads for all samples. Meanwhile, the average COF values have decreased with increasing applied loads. Furthermore, shallower wear grooves and smoother worn surfaces were observed for zeolite/UHMWPE composites as compared to pure UHMWPE. In terms of the transfer film observation, the counterface of pure UHMWPE were partially covered, rough, and discontinuous. On the other hand, counterface of zeolite/UHMWPE composites were fully covered, smooth, and continuous. Overall, the tribological properties showed significant improvement with the reinforcement of zeolite in UHMWPE. (C) 2013 The Authors. Published by Elsevier Ltd.