Thermal conductivity and surface dielectric properties of micro sized BN filled polyethylene

Polyethylene (PE) has excellent insulating properties but low thermal conductivity. Embedding boron nitride (BN) filler into pure PE is an effective method to increase the entire thermal conductivity of PE composite, which also affects its resistance to surface dielectric breakdown (c.f. tracking failure). This paper is aimed at investigating the effects of micro-sized BN particles on the thermal conductivity as well as the process of tracking in PE/BN composites under pulse strength. To prepare PE/BN composites with filler loadings of 0, 10, 20, 30 and 40 wt%, micro sized BN particles were dispersed into pure PE. Relative permittivity, thermal distribution, time to tracking failure (TTF) and the damage degree of the test sample were discussed. The experimental results show that thermal conductivity and TTF increase with increasing filler content, whereas the maximum temperature and the damage degree on the sample surface show opposite trends. In addition, it also reveals that the relative permittivity of the filled sample could still maintain a relatively low value.