Surface Modification Of Nano-sized Silicon Nitride By Polymethylacrylate And Study On Nano-Si₃N₄/EPDM Composite

Composite material is composed of metallic, inorganic non-metallic or polymer material and it is a kind of multiphase material, which possesses a superior cooperative performance. There are combined effects from the composite material and there is not the performance for the single component of the composite material. Composite material based on polymer with nano-size is a kind of inorganic-organic composite material and the inorganic filler is dispersed in the polymer with nanno-size. In order to improve the dispersion of the inorganic nano particles in the polymer, the surface of inorganic nano particles should be modified by macromolecular due to the properties of non-consistent between the interface of inorganic and organic. Here, the surface of silicon nitride(Si₃N₄) ceramic nano particles has been modified by macromolecular surface modifier which is synthesized in our laboratory and the Si₃N₄ is filled into ethylene propylene diene monomer(EPDM), meanwhile, the performance of EPDM is discussed.The first chapter is related to the synthesis of zinc methacrylate nanocrystal and the characterization for zinc methacrylate nanocrystal using IR, NMR, TEM and X-ray diffraction. The results indicate that the zinc methacrylate nanocrystal is better than that of the congener products from the United States. We have optimized the experimental conditions, such as temperature, concentration, dropping and stirring rate, by parallel test.The second chapter is concerning of the surface modification and characterization of the nano silicon nitride powder. Nano silicon nitride powder is coated by Zinc methacrylate synthesized in situ polymerization and the optimization ratio of coating and the experimental conditions of nano silicon nitride powder are determined. The results of IR, TEM, SEM show that the surface of nano silicon nitride has been modified by macromolecular surface modifier and there is a group of chemical bond between the interface of nano silicon nitride powder and the macromolecular surface modifier.The third chapter is about ethylene-propylene rubber filled and modified by nano silicon nitride which is modified by zinc methacrylate. We have synthesized nano silicon nitride / rubber composites and dealt with the dispersion of nano silicon nitride in rubber. We have also discussed the mechanical properties of the composite material, the dynamic mechanical properties, the heat aging properties and the oil resistance etc,. The results show that the modified nano Si₃N₄ has been dispersed well in the rubber matrix, and the avulsion intensity, the tensile strength, the abrasion resistance, the oil resistance of the ethylene-propylene rubber have been improved, especially in the resistance of heat oil of ethylene-propylene rubber.