Electrified Polyolefin/Multiwall Carbon Nanotube Composites Exhibit Dramatic Changes in Electrical Conductivity, Permittivity, and Filler Structure

Abstract

Electrically insulating polyolefin composites containing well‐dispersed multiwall carbon nanotubes up to 3 wt.‐% are subjected to AC electric fields in the range of 71–212 kV m−1. Their resulting filler structure, DC conductivity, and AC dielectric properties are compared with the respective properties of their non‐electrified and annealed counterparts. As evidenced by TEM, electrification causes the formation of aligned filler structures in the direction of the electric field within the composite, whereas annealing alone results in the formation of randomly interconnected nanotubes. Dielectric spectroscopy shows that, due to their ordered carbon nanotube structures, the electrified composites exhibit substantially higher conductivity and storage capacity compared to the as‐compounded composites and consistently better electrical properties than their annealed counterparts. An equivalent circuit model is fitted to the experimentally obtained impedance data in order to correlate the effects of electric field and processing time to the resulting dielectric characteristics of the treated composites.