Performance of silicone rubber composites using boron nitride to replace alumina tri‐hydrate

Abstract Boron nitride (BN) has attracted increasing attention as a filler using in insulating materials. In this work, by using an equal amount of BN to replace alumina tri‐hydrate (ATH), various SR/BN/ATH composites were prepared, and for comparison, vinyl tri‐methoxysilane (VTMS) was added to prepare SR/BN/ATH‐VTMS composites. With the increasing BN content, Shore A hardness, breakdown strength and thermal conductivity of the silicone rubber (SR) composites increased despite the tensile strength slightly reduced. By replacing all the ATH with BN, the SR composite showed a ∼47% increase in breakdown strength, reaching 33.8 kV mm−1. The lower dielectric constant and dielectric loss were found for the SR composites with higher BN content, while the decreased dielectric loss and increased dielectric constant were achieved by the introduction of VTMS. Owing to the improved filler‐rubber interfacial interactions by adding VTMS, with the same BN content, all the SR/BN/ATH‐VTMS composites exhibited better property than the SR/BN/ATH composites. The best thermal conductivity of the SR composite reached 0.448 Wm−1 K−1, ∼156% higher than that of the ATH filled SR composite.