| Ultra-high molecular weight polyethylene (UHMWPE)/inorganic particle composites and organically cross-linked UHMWPE are studied in this paper. Firstly, from the forming processes of UHMWPE, compression molding process was chosen as the proper one for this study. In order to modify UHMWPE, inorganic superfine powders with different particle diameters, such as nano-SiO2, 5000mu and 2500mu glass heads, were filled in UHMWPE, or UHMWPE was cross-linked by peroxide. Varying the dosage of fillings, coupling agent, peroxide, and the mixing techniques, the UHMWPE composites were molded by compression molding. Having analyzed the dispersion of particles in composites by SEM(Scanning Electron Microscopy), tested the Vicat softening temperature, mechanical properties such as tensile strength, hardness, we concluded that the filled UHMWPE composite has a better heat resistance, meanwhile the other physical properties improved or maintained or descended appreciably. The UHMWPE/nano-SiO2 composite behaves better in heat resistance with a relatively small quantity of fillings, while UHMWPE/5000mu glass heads composite does better with a relatively large quantity of fillings. Moreover, it showed that the fillings distributed by air current have the better properties than general mechanical mixture。The fusion-crystal action of UHMWPE/nano-SiO2 composite filled with varied content of nano-SiO2, which was prepared by compression molding process was studied by means of Differential Scanning Calorimetry (DSC). It is showed that the filled nano-SiO2 acted as nucleating agent. The characteristics and crystal structure of UHMWPE/nano-SiO2 composites with varied content of nano-SiO2 are studied and observed by Polarizing Microscope, and was compared with the pure UHMWPE. The results show that nano- SiO2 acts as a nucleation agent in UHMWPE and heterogeneous nucleation domains during the crystallization, thus upgrade the crystal temperature and diminish the spherulites of the crystal.
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