Comparison of properties and thermal modification of thermal expansion silicone rubber

In order to obtain thermal expansion silicone rubber for composite soft molding with excellent performance and wide adaptability, the flow, heat resistance, thermal expansion and elastic properties of three kinds of thermal expansion silicone rubber were tested. Two kinds of silica particles were added and dispersed into the thermal expansion silicone rubber by the way of grading composite dispersion. Then the flow, heat resistance and thermal expansion of silicone rubber were studied. The results show that silicone rubber Ⅰ have the advantages of slow increase of curing reaction viscosity, long curing time, best heat resistance and thermal expansion properties, and is suitable for soft molding of composite materials. The silicone rubber Ⅰ is filled with a maximum of 2 phr of nano-silica and 60 phr of micron silica which has a better modification effect than that of nano-silica. When the amount of micron silica is 60 phr, the average linear expansion coefficient of silicone rubber is 210.0×10-6 ℃-1 from room temperature to 200 ℃, which is about 22% lower than that of silicone rubber without added filler. The average elastic modulus of silicone rubber is 4.7 MPa from room temperature to 200℃, which is about 96% higher than that of silicone rubber without filler. The results meet the demand for thermal material modification of silicone rubber and expands the application scope of thermal expansion silicone rubber for soft mold molding process.