Abstract:With the continuous development of electronics industry, high thermal conductive and insulating polymer composite have attracted much attention because they can not only improve the operational reliability of electronic components, but also improve their safety and service life. In order to develop high-quality thermal conductive and insulating composites, EPDM rubber was used as the matrix material of insulating polymer materials, and Al2O3 with particle size of 2, 10, 20, 40 and 70 μm were selected as thermal conductivity filling materials, and Al2O3/EPDM insulating and thermal conductive composite was prepared by open mill. The properties of Al2O3/EPDM composites under the particle size of Al2O3 were investigated by characterizing the vulcanization properties, mechanical properties, thermal conductive and insulating composites of the composites. The results show that the crosslinking degree of the composite decreases gradually when the particle size of Al2O3 increases, the thermal conductivity increases first and then decreases, and the volume resistivity decreases as a whole, and when the particle size of Al2O3 is 10 μm, the comprehensive performance of Al2O3/EPDM thermal conductive and insulating composites is the best.