Polyethylene/silica nanocomposites: absorption current and the interpretation of SCLC

Abstract

The topic of nanodielectrics continues to receive significant attention from today's dielectrics community, due to the property enhancements that can stem from the unique interfacial features within such material systems. Nevertheless, understanding the interfacial phenomena that occur in nanodielectrics, which determine their electrical behaviour, is challenging. In this paper, we report on an investigation into the absorption current behaviour of two nanocomposite systems, one containing an untreated nanosilica and the other containing the same nanofiller chemically modified using trimethoxy(propyl)silane. The results indicate that the absorption current behaviour of all the nanocomposites is very different from that of the reference, unfilled polymer; while the current flowing through the unfilled polyethylene decreased monotonically with time in a conventional manner, all the nanocomposites revealed an initial decrease followed by a period in which the current increased with increasing time of electric field application. Possible mechanisms leading to the observed absorption current behaviour in the nanocomposites are discussed with the aid of space charge measurements. The presence of space charge limited conduction (SCLC) and its trap-filled limit is proposed.