Mechanical And Tribological Properties Of Ultra High Molecular Weight Polyethylene With Zinc Oxide Antibacterial Agent For Joint Implant

• Main Author: Chang, Boon Peng
• Format: Thesis
• Language: English
• Published: 2014
• Subjects: T Technology; TA401-492 Materials of engineering and construction. Mechanics of materials
• Online Access: http://eprints.usm.my/47958/1/Mechanical%20And%20Tribological%20Properties%20Of%20Ultra%20High%20Molecular%20Weight%20Polyethylene%20With%20Zinc%20Oxide%20Antibacterial%20Agent%20For%20Joint%20Implant.pdf; http://eprints.usm.my/47958/
• Institution: Universiti Sains Malaysia

Total joint replacement (TJR) is a highly successful treatment for end-stage joint disease like osteoarthritis. A prominent number of TJR devices used in orthopaedic involve articulation between a metallic alloy and ultra-high molecular weight polyethylene (UHMWPE). Although this polymer has excellent properties, suitable for TJR bearing materials, the wear particulate produced due to relative motion between components still remains an issue yet to be resolved. This study presents approaches to improve the wear performance of UHMWPE in implant applications by various types of fillers reinforcement. The UHMWPE composites were fabricated by compression moulding with different filler-matrix ratios. These composites were characterized and compared in terms of their mechanical and tribological properties. The filler which delivered the best performances were selected as the filler in the UHMWPE hybrid composites. The tribological properties was investigated using pin-on-disc tester under different loads and sliding speeds. The worn surfaces and transfer films produce after wear test were studied under scanning electron microscopy (SEM). This research consists of four parts. The first part was to investigate the effect of surface treatment of ZnO on the mechanical, tribological and antibacterial properties. Two variants of untreated ZnO-reinforced UHMWPE (U-ZPE) and treated ZnO-reinforced UHMWPE (T-ZPE) with aminoproply-triethoxysilane (APTES) were used to compare the improvement of properties. The antibacterial assessments of the composites were tested against two common human body bacteria i.e. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Results have shown that T-ZPE possess higher mechanical and wear properties as compared to U-ZPE. Both U-ZPE and T-ZPE composites showed active inhibition against E. coli and S. aureus bacteria. T-ZPE showed higher percentage inhibition against the tested bacteria. The second part of the research was compared the performances of the micro- and nano-ZnO reinforcement in the UHMWPE composites. The wear properties of nano-ZnO/UHMWPE composites are better than micro-ZnO/UHMWPE. The nano-ZnO/UHMWPE composites impart superior antibacterial properties as compared to micro-ZnO/UHMWPE composites. The third part of the research studies the influence of silicate mineral reinforcements (zeolite and talc) on the properties of UHMWPE. In terms of mechanical properties, the zeolite/UHMWPE showed superior mechanical properties as compare to talc/UHMWPE. However, for wear resistance, talc/UHMWPE exhibited better wear behaviour as compared to zeolite/UHMWPE. There is no direct relationship of degree of crystallinity (DOC) on the tribological properties of UHMWPE composites. Finally, in the fourth part of the research, the effects of two types of filler reinforcements i.e. particulate (talc particles) and fibre (glass fibre (GF))-reinforced ZnO/UHMWPE hybrid composites on the tribological properties were carried out. The empirical models on the relationship of various variables of applied loads, sliding speeds and distances on the wear and friction of UHMWPE composites was developed using Response Surface Methodology (RSM). Optimization of the responses as function of independent variables were generated. GF/ZnO/UHMWPE exhibited better wear performance compared to talc/ZnO/UHMWPE hybrid composites.