Investigation of the electrical properties of XLPE/SiC nanocomposites

The interface between nanoparticles and the polymer matrix, which dominates the electrical properties of nanocomposites, can effectively improve the DC breakdown and suppress space charge accumulation in nanocomposites. To research the interface characteristics, XLPE/SiC nanocomposites with concentrations of 1 wt%, 3 wt% and 5 wt% were prepared. The DC breakdown, dielectric properties and space charge behavior were examined using pulsed electro-acoustic (PEA) equipment and a dielectric analyzer. The test results show that the nanocomposites with concentrations of 1 wt% and 3 wt% have higher DC breakdown field strength than neat XLPE. In contrast, there is a lower DC breakdown strength at a concentration of 5 wt%, possibly due to the agglomeration of nanoparticles. Nanoparticle doping increases the real and imaginary permittivities over those of neat XLPE. Furthermore, with increasing concentration, a larger increase in the permittivity amplitude was observed. Based on the space charge behavior, all nanocomposites could suppress space charge accumulation, but the nanocomposite with a concentration of 1 wt% exhibited the best effect. Meanwhile, heterocharge accumulation near electrodes was observed in neat XLPE and the nanocomposite with a concentration of 5 wt%. In contrast, homocharge accumulation near electrodes was observed in the nanocomposite with a concentration of 3 wt%. This phenomenon may be due to different amounts of shallow traps in nanocomposites with different concentrations, which might lead to differing electron or hole mobility.