Thermally conductive silicone rubber used as insulation coating through incremental curing and the effects of thermal filler on its mechanical and thermal properties

With the rapid development of the electronics, communication, and energy industries, there is an increasing demand for flexible materials with high thermal conductivity and electrical insulation properties. Silicone rubber (SR) is widely used in various fields due to its excellent mechanical properties. However, its intrinsic low thermal conductivity requires the addition of thermally conductive fillers to enhance its thermal conductivity. Insulating thermally conductive composites are prepared by adding thermally conductive fillers such as boron nitride (BN) and graphite into a silicone rubber matrix. When BN is added as a single filler up to 20 wt%, the thermal conductivity of BN/SR reaches 0.526 W m −1 K −1 , which is a 126% improvement compared to the SR matrix. When the total filler content is 20 wt%, and the ratio of BN to graphite is 1:1, the thermal conductivity of BN/graphite/SR composite is 0.685 W m −1 K −1 . This represents a 194% and 30% increase in thermal conductivity compared to the SR matrix and BN/SR composite with the same filler content, respectively. On the cured silicone rubber substrate, the incremental cured BN/SR acts as an insulation coating. This allows for a significant reduction in the electrical conductivity of the composite without the use of adhesives, while preserving the thermal conductivity. Moreover, the interface formed through incremental curing retains high tensile and compressive strength.