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Rubber Modified Epoxy Resin

Jul 03, 2020

The internal stress of the cured epoxy resin is large, brittle, easily degraded at high temperature, and easily affected by water. Modification with rubber can reduce its internal stress, increase toughness, improve heat resistance, oil resistance, water resistance, weather resistance and other properties. In order to improve the toughness of solvent-free epoxy adhesives, oligomers of various elastomers are generally used as tougheners at home and abroad. Modified elastomers usually have active groups (such as carboxyl, hydroxyl, amino, etc.), and ring Oxygen reacts to form grafts and blocks. During the resin curing process, these elastic segments generally precipitate from the matrix to form a two-phase structure. The main role of the rubber phase is to induce the energy dissipation process of the matrix, and its energy dissipation in the fracture process plays a secondary role, at the same time it can reduce the internal stress and increase the effects of heat resistance and weather resistance. Since the Si-0 bond has a high bond energy (106 kcal mol), its polymer molecular chain has a high degree of curlability, and the use of silicone to modify the epoxy resin can make it thermally stable, weather resistant, brittle, etc. Obviously improved, at the same time, because the low surface free energy polysiloxane is applied to the resin surface, the epoxy resin waterproof and oil resistance properties can be improved. Because silicone is incompatible with epoxy resin, NH2, OH, OR of silicone and epoxy of epoxy resin are generally used for grafting or copolymerization to reduce the interfacial energy of the two and change the compatibility of the two. The obtained polysiloxane and As70 epoxy resin were grafted under the action of a catalyst. After modification, Tg increased by 9℃, and T (the starting temperature of thermal decomposition) and Tox (the peak temperature of thermal decomposition) both increased by about 30℃. Obviously, the heat resistance was greatly improved. In addition, the silicone modified with hydroxyl group, phenolic hydroxyl group, amine group and epoxy are graft modified, which also improves the heat resistance of epoxy resin and reduces the internal stress. The above is a brief introduction of rubber modified epoxy resin.