Multi-length scale wear damage mechanisms of ultra-high molecular weight polyethylene nanocomposites

Abstract Ultra-high molecular weight polyethylene (UHMWPE) is reinforced with 1–3 wt % sliver (Ag) nanoparticles and zinc oxide (ZnO) micro-rods and tensile strength as well as wear resistance of the samples is evaluated. Tensile strength was found to increase with Ag and ZnO reinforcement up to 18% for 1 wt % ZnO and 1 wt % Ag, but in case of 3 wt % ZnO and 3 wt % Ag + 3 wt % ZnO, it decreases marginally by 4% when compared with neat polymer. The sliding wear rate for 1 wt % Ag + 1 wt % ZnO (U1A1Z) and 3 wt % Ag + 3 wt % ZnO decreases from 9.54 × 10−5 mm3 (neat polymer) to 7.49 × 10−5 mm3 and 5.65 × 10−5mm3, respectively, showing the synergistic effect of Ag and ZnO reinforcement. In scratch testing, minimum damage is obtained in 1 wt % ZnO reinforced polymer. On one hand, where micro-scratch damage is resisted by harder ZnO, whereas on the other hand, pin on disc wear (repeated surface damage) is protected by softer Ag tribolayer. The improved tensile strength (up to 9.7% more than neat UHMWPE) and wear resistance in U1A1Z opens a window in the development of bearing surface biomaterials providing improved longevity and durability, thus, may reduce the chances of revision surgery.