Electrical treeing in LDPE-EVA blend based nanocomposites

In this work thermoplastic polymeric blends based on low density polyethylene (LDPE) and ethylene vinyl acetate (EVA) have been investigated. The blends have been obtained mixing together portions of 80% of LDPE and 20% of EVA adding montmorillonite and silica as fillers to get different nanocomposite materials with different nanofillers amounts: chosen percentage were 3% and 7% by weight. The aim of this research program was to identify the behaviour of these nanocomposite blends when subjected to electrical treeing and to identify the effect of the interface polymer matrix - nanofiller and the effect of the blends chemical-physical structure on the tree growth. The materials have been prepared by twin screw compounding following an optimized procedure leading to obtain good quality blends. The homogeneity of the compound has been verified by means of chemical-physical analysis. Suitable specimens have been realized by hot compression moulding. Electrical needle-plane tests have been performed in order to evidence the performance of the nanocomposite blends against the treeing growths.