Space Charge Distributions in Two-layered LDPE/MgO Nanocomposites Exhibiting Superior Insulation Performance

Abstract

Recently polymer nanocomposite has been attracting much attention as an emerging insulating material. In this paper, we measured space charge distributions for two-layered dielectric films consisting of certain combination of low-density polyethylene (LDPE) and its nanocomposite with magnesia nano-fillers during the application of dc electric field of 25 kV/mm or 100 kV/mm. Both at room temperature and 50°C, space charge is formed at the interface of two different materials to maintain the continuity of current when the electric field is 25 kV/mm, while packet-like charge appears only in the LDPE when the electric field is 100 kV/mm. These phenomena are explained by assuming that the nano-fillers effectively suppress the increase in conductivity induced by the high electric field.