Electrical and thermal conductivity of ethylene vinyl acetate composite with graphene and carbon black filler

Ethylene vinyl acetate (EVA) composites, including two different carbonaceous conductive fillers, carbon black (CB) and commercially available graphene (G), were fabricated by solvent-casting and melt compounding methods. The effect of additives and process conditions on electrical and thermal properties of composites was investigated. The dielectric responses of EVA composites were characterized by a percolation threshold of 15 wt % for EVA/G prepared by solvent-casting. However, as the EVA/G15% was also subsequently extruded, the applied shear stress induced by extrusion caused deterioration of the electrical network and reduced the composite's electrical conductivity. A percolating network was found for the EVA composites containing CB at around 5-7 wt % with 10 orders of magnitude increase in electrical conductivity with respect to the neat EVA. The thermal conductivity of EVA/CB7% and EVA/G15% increased 16 and 22% respectively, in comparison to the neat EVA. Both additives increased the electrical and thermal conductivity of composites to be appropriate as jackets for high-voltage cables.