Microscopic and nanoscopic EVA composite investigation: Electrical properties and effect of purification treatment

This work presents preliminary results of an investigation aiming at characterization of nanocomposite insulating materials. Focus is made on size and technological process effects, i.e. dependence of electrical properties on filler size, on polymer-nanofiller interaction (e.g. intercalation or exfoliation) and, in particular, on chemical purification procedures. The materials under investigation are (EVA) copolymer filled by layered micro and nanosized silicates consisting of montmorillonite and fluorohectorite, that is, natural and synthetic clays. Microstructural characterization, using transmission electron microscopy, TEM, and wide-angle X-ray spectroscopy, WAXS, and electrical measurement results, particularly space charge, are presented and discussed, showing that nanostructuration of EVA-synthetic clay, especially in the exfoliated morphology, can give rise to interesting modification of electrical properties, only if, however, chemical purification of nanofillers is carried out effectively.