Suppression of packet-like space charge formation in LDPE by the addition of magnesia nanofillers

Space charge distributions were investigated in two-layer dielectric films consisting of certain combinations of low-density polyethylene (LDPE) and its nanocomposite with magnesia nanofillers at DC electric fields of 25 kV/mm and 100 kV/mm at room temperature. 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 at 100 kV/mm. These phenomena are explained by assuming that the nanofillers effectively suppress the increase in conductivity induced by the high electric field. Related work done previously by the authors is also briefly reviewed.