Dielectric and thermal properties of micro/nano boron nitride co-filled EPDM composites for high-voltage insulation

Ethylene propylene diene monomer (EPDM) is a polymeric material widely used for high-voltage insulation. This work reports the dielectric and thermal properties of EPDM co-filled with micro- and nano-BN particles. EPDM composite samples with different micro and micro/nano co-filled contents are prepared by melt-blending and followed by hot press application. Measurements were made including broadband dielectric spectroscopy, thermogravimetric analysis and thermal conductivity. Experimental findings indicate that Micro-25 wt% + Nano-5 wt% performs better in terms of dielectric loss and conductivity whilst the dielectric constant is measured lower in Micro-29 wt% + Nano-1 wt% relative to the equivalent micron filled Micro-30 wt%. Moreover, the initial degradation temperature and final residual masses of co-filled composites are found considerably higher. The thermal conductivity of EPDM is highly influenced by the introduction of co-filled set of particles and it is measured about 0.465 W/m.K in Micro-29 wt% + Nano-1 wt% which is 18% higher than Micro-30 wt%. It is likely that the denser packing geometry due to co-filled set of particles inside the EPDM matrix improves the dielectric and thermal properties which make such composites more attractive for electrical insulation applications.