Improved Surface Electrical Properties of Polystyrene in Vacuum by Plasma Modification

In order to satisfy the demand of industry development, the improvement of the surface insulation performance of polystyrene (PS) is urgent. It is believed that the accumulation of charge on the material can induce the distortion of local electric field, even cause surface flashover. Therefore, in this paper, in order to reduce the accumulation of surface charge, inorganic nano-films are deposited on the surface of PS by plasma modification technology. The plasma excitation source is AC high voltage generator with a frequency of 20 kHz. The PS samples are treated with tetraethoxysilane (TEOS) precursor assisted by plasma for 10 minutes. The working gas is argon and the pressure is sub-atmospheric (2 kPa). Before and after the plasma modification, surface charge accumulation and dissipation characteristics are measured. The results show that the decay rate of surface charge is increased obviously for modified PS. The Fourier Transform Infrared Spectrum (FTIR) indicates that new groups of Si-O-Si, Si-OH are formed on the sample surface. The trap energy level induced by the above groups is lower, namely, the shallow traps are beneficial to the dissipation of surface charge. Thus, the surface flashover withstand voltage is improved significantly.