Studies on The Modification of Epoxy Resin with Silicone Rubber

In order to find a compatibilizer for epoxy resin/silicone rubber systems, interfacial tension of epoxy resin mixed with modified silicone oils which had the compatible groups to epoxy resin was measured against RTV silicone rubber and silicone oil. From the results, it was found that one of polyether modified silicone oils (EtMPS) had strong interfacial activity. Then using the EtMPS as the compatibilizer, RTV silicone rubber or silicone diamine was filled in epoxy resin. The effects of silicone content of these materials on impact fracture energy and on peel strength were investigated. The impact fracture energy of epoxy resin was increased by the addition of RTV silicone rubber up to two times that of unmodified resin while silicone diamine had almost no effect which might be due to the small molecular weight. T-peel strengths of aluminium plates bonded by epoxy resin filled with RTV silicone rubber and with silicone diamine effectively increased with the increasing of silicone content showing the maximum at 10 ～ 20 phr. The fracture surfaces after the mechanical tests of these materials were observed by a scanning electron microscope. Many particles of silicone rubber in the size of 1 ～ 20 μ were observed over the fracture surface.