THE “MODIFIED” ULTRA-HIGH-MOLECULAR-WEIGHT-POLY-ETHYLENE (UHMWPE): NEW DEVELOPMENTS AND APPLICATIONS

Ultra-High-Molecular-Weight-Poly-Ethylene (UHMWPE) is an high-performance thermoplastic polymer, used alone or chemically and physically modified. It is also often combined with other materials such as ceramics or metals. Application fields range from the bio-medical to in civil engineering. UHMWPE has very interesting features such as chemical inertia, biocompatibility, high strength, high mechanical and corrosion resistance, welding capacity, low friction, and electrical insulation. This material also has unfavorable aspects. The first is represented by its very high viscosity and, therefore, the complexity of dispersing the fillers within the polymer matrix. Another is its workability, being difficult to work with the common technologies used to treat thermoplastic polymers. Moreover, especially for long-term applications, it needs to be improved in some specific characteristics to increase its service time, such as oxidation resistance, wear resistance, surface characteristics (for better wettability or adhesion with other polymeric materials, etc.). In this study the possible modifications of UHMWPE in terms of material composition and through specific physical treatments are discussed. The nanocomposites were prepared and tested against pure UHMWPE. Likewise, pure UHMWPE was irradiated from different sources of irradiation. Both bulk and surface induced changes in modified UHMWPE have been investigated by several analyses. For this purpose, static and dynamic mechanical tests, rheological, thermal, morphological, and surface analyses are presented.Besides, degradation studies of the pure and modified UHMWPE have been performed in real or simulated biological media, or under an imposed wear stress. These investigations are necessary to deeply understand the degradation mechanisms that occurs in UHMWPE. The changes in physical and mechanical behavior of the nanocomposite have been studied to check the enhanced properties with respect to the pristine material.