Electrical properties of polymer nanocomposites based upon organophilic layered silicates

An investigation on space charge and conduction properties of electrical-insulating polymer nanocomposites is presented. Space charge, conduction current and electric strength measurements were performed. Different poling field were considered, in order to derive the space charge accumulation characteristics and infer the mechanisms for conduction and trapping of charge carriers. Two families of insulating materials were considered, that is, isotactic polypropylene, PP, and a copolymer ethylene-vinylacetate, EVA, both filled by organophilic layered silicates as nanomaterials. The comparison among unfilled and nanofilled materials, with different filler concentrations, shows that space charge accumulation phenomena are considerably affected by the presence of nanofillers: space charge accumulation threshold, but also the density of trapped charge at high fields, decrease, in fact, as nanofiller content increases. Likewise, conduction current increases for nanofilled materials. Electric strength can be also positively affected by nanofillers.