Effects of 2D boron nitride (BN) nanoplates filler on the thermal, electrical, mechanical and dielectric properties of high temperature vulcanized silicone rubber for composite insulators

Degradation of the silicone rubber in the composite insulators is usually caused by thermal and electrical stressing. The thermal conductivity of the composite insulator can be improved by adding a second phase with high thermal conductivity. Boron nitride is a new kind of two-dimentional (2D) materials, with a microstructure similar to the popular graphene but electrically insulating. Such unique properties make BN a promising candidate for increasing the thermal conductivity while maintaining the electrical insulating properties of the silicone rubber. In this report, we systematically studied the effects of BN nanoplates as a filler on the thermal diffusivity/conductivity, electrical breakdown strength, mechanical performance, dielectric behavior, as well as hydrophobicity properties of high temperature vulcanized silicone rubber. A series of samples were prepared with different BN filler loadings up to 32 wt% (∼25 vol%). We found that after adding BN nanoplates the sample's thermal conductivity can be increased by 30%. Surprisingly the electrical breakdown strength and hydrophobicity were also improved by the BN filler. However, the mechanical strength was deteriorated to some extent. Our results provide new thoughts in optimizing the performance of the silicone rubber for composite insulators. More studies need to be done in order to reveal the effects of BN additives in real composite insulators.