Preparation And Properties Of High Damping Composite Material Based On Silicone Rubber

With the development of society and modern industrialization, the pollution of vibration and noise is growing worse and has brought about lots of inconvenience and harm to people’s lives, therefore, it has been an active area of research to reduce vibration and noise absorption. At present, the rubber-based damping material is still the main damping material for vibration reduction. Damping materials with good performance must meet the requirements that the temperature range of high loss factor（tanδ>0.3） is over at least 60⁸0°C and the effective damping temperature range must be consistent with the actual operating temperature as well. Silicone rubber has the outstanding performance in many aspect, such as high & low temperature resistance, heat aging stability, weather resistance and stable mechanical properties and it is widely used in the field of electrical and electronics, aerospace and medical devices. In some specific areas, we need materials with excellent high & low temperature resistance, weather resistance and good damping properties, and silicone rubber will be the best choice. However, pure silicone rubber has low loss factor（ tanδ <0.2） and narrow damping temperature range, so it will be of important engineering significance to improve its damping properties.Damping materials based on the blending of Vinyl Methyl Silicone rubber（MVQ） and inorganic fillers such as spherical alumina（Al₂O₃）, halloysite nanotubes（HNTs） and flake mica were prepared in the present study. It has been found that the surface modification and micromorphology of inorganic fillers have a great influence on damping properties of the composite. The results showed that silane coupling agent could on the one hand improve the interfacial compatibility of MVQ and inorganic fillers, while on the other hand limit the movement of filler particles and reduce the damping property. Compared with the modification by silane coupling agent, using admicellar polymerization to coat a nano-layer of Polypyrrole（PPy） on the surface of Al₂O₃ was more conducive for energy transfer and energy loss, so it could improve the material damping property better. The micromorphology of inorganic filler also had an important impact on the damping properties of composite. Compared with Al₂O₃, HNTs and mica have larger aspect ratio and specific surface area that there was more internal friction in the composite and it was more advantageous for energy consumption. In MVQ/mica composite, the MVQ molecular chains would intercalate into the laminates of mica and form the constrained damping structure, which would further enhance the damping property of composite. Besides, applying smaller particle size and larger particle amount would endow the composite with better performance. Silicone composite with tanδ peak value of 0.45 and damping temperature range of broader than 120℃（-66.8⁵5.1℃）was prepared by filled 150 phr of mica with particle size of 3000 meshes.Ethylene Acrylate rubber（AEM） was used to blend with MVQ by co-vulcanization to increase the damping properties, mechanical properties and oil resistant properties of MVQ. And it was found that the introduction of mica could improve the damping properties of MVQ/AEM blends. With the increasing amount of mica, the tanδ peak moved to higher temperature and the effective damping temperature range broadened, but when the amount reached a certain extent, the material damping properties changed little. Simultaneously, the composite had good damping properties within wide frequency（10-5 1015Hz）. Composite with the best-ever performance was prepared by filled 75 phr of mica while the blending ratio of MVQ/AEM was 50/50 and its effective damping temperature range was about 100 ℃（-36.0⁶3.5℃） and effective damping frequency range was between 10-3¹010 Hz.