Effects of nano-sized MgO-filler on electrical phenomena under DC voltage application in LDPE

A nanocomposite material, composed of nano-sized MgO-filler added to a low-density polyethylene (LDPE), was subjected to electrical property investigations under DC voltage application. The volume resistivity of LDPE, under 40-80 kV/mm DC field at 90 °C, increases by the power of 10 due to the addition of only a few percent of nano-filler. The amount of space charge in LDPE under high electric field is reduced and the ratio of stress enhancement by space charge becomes less due to the addition of nano-sized MgO-filler. The DC breakdown strength of LDPE is increased by adding nano-sized MgO-filler. Based on these results, the mechanism where by the nano-sized MgO filler had improved DC characteristics of LDPE was discussed.