Study on electrical properties and thermal conductivity of carbon nanotube/epoxy resin nanocomposites with different filler aspect ratios

Multi-walled carbon nanotube/epoxy resin (MWCNT/EP) composites with filler contents from 0.03wt% to 0.5wt.% and two different aspect ratios are prepared by solution blended process. Carbon nanotubes are dispersed by sonication and high speed shear force. The impact of aspect ratio on electric and thermal conductivity of nanocomposites has been studied. Experiment results illustrate that percolation threshold of electrical conductivity decreases with the increase of aspect ratio of carbon nanotube and the lowest percolation threshold is about 0.05wt.%. Strong nonlinear DC electrical conductivity behavior caused by field emission is observed. Both the increase of aspect ratio and approach of percolation threshold increases the nonlinearity. With the increase of filler content, AC conductivity is less dependent on frequency. Thermal conductivity of nanocomposites increases with filler content. The increase of aspect ratio is also positive to improve thermal conductivity. The thermal conductivity of nanocomposite with 0.5wt.% filler content and highest aspect ratio is about 26% higher than that of neat epoxy.