Study on Space Charge Behaviour in Polyethylene Doped with Nano-Montmorillonite

Space charge existed in polymer subjected DC high electrical stress has attracted more and more attention over the world. Various methods of inhibiting space charge generation and accumulation had been attempted in order to reduce insulation deterioration. In the present paper, the polyethylene/montmorillonite nanocomposites are prepared by melting intercalation process. The distribution of space charges in the nano-composite is investigated by means of pulse electric acoustic (PEA) method under different conditions. The effects of maleic anhydride grafted polyethylene (PEMA) on space charge characteristics of the composites are discussed. The test results indicate that the heterogeneous space charges in the nanocomposite near the cathode gradually decrease with PEMA content increasing. When PEMA content is 20%, the heterogeneous space charges near the cathode almost disappear at all in the nanocomposite. In short-circuiting process, the residual space charges in the nanocomposite with compatilizer obviously decrease comparing with origin LDPE. It is suggested that PEMA as a compatilizer can improve the interaction combination between LDPE and O-MMT, consequently interfacial traps reduce.