Effect of nano-fillers distribution on the nonlinear conductivity and space charge behavior in SiC/PDMS composites

Flexible polymer based materials with excellent breakdown strength and weak space charge behavior have been widely used in the field of cable insulation and cable termination. The silicon carbide (SiC) is beneficial to homogenize the electric field distributions, suppress the space charge injection and enhance the dissipation in the polymer composite. In this work, the polydimethylsiloxane (PDMS) based composites filled with β-SiC nanoparticles were prepared by solution mixing and mechanical blending, respectively. Compared with the pure PDMS, the SiC/PDMS composites possess not only the increased nonlinear conductivity coefficient but also the largely enhanced capability of dissipation of space charge. Especially under high electric field environment, the impact caused by uneven distribution of the SiC fillers was significant. The results of the space charges measurement under high electric field revealed that the SiC nanoparticles could largely enhance the dissipation and accelerate the movement of space charge, which was due to less trap sites leading to the better dispersion of SiC nanoparticles.