Surface flashover in vacuum and bulk breakdown in polystyrene nanocomposites

Nano-sized Al₂O₃ and TiO₂ particles are mixed with polystyrene to prepare specimens, respectively. In this paper, the dielectric relaxation spectroscopy, breakdown strength and surface flashover voltage in vacuum of nanocomposites were investigated. Both breakdown strength and flashover voltage first increase, then decrease with increasing the fillers loading. They are also dependent on applied field waveform. However, permittivity shows a decrease at slight filler loading, and then increases. According to the experimental results, specimens with lower permittivity have higher electric strength. The permittivity, breakdown strength and surface flashover are close related to the interaction zone between nanoparticle and polymeric matrix. Moreover, it should be emphasized that there is a certain relationship between bulk electric strength and surface flashover voltage.