Optimization of the Electrical Conductivity of ABS Nanocomposites filled with Carbon Black and Carbon Nanotubes

Abstract

Poly(acrylonitrile-co-butadiene-co-styrene) (ABS) is a thermoplastic polymer that is used in numerous structural applications as a result of its excellent mechanical properties. For those applications where good electrical conductivity is also desired, carbon black is often used as the filler of choice. Most reports in the literature indicate that at least 8 wtcarbon black filler is needed in order to achieve percolation. Our group recently reported that by manual mixing of ABS pellets and carbon black to create a segregated microstructure, percolation was achieved at an unprecedented low filler fraction of less than 0.01 wtcarbon black, a value which is comparable to or even better than that obtained using single wall carbon nanotubes as the filler. While the ABS/CB composites had excellent electrical performance, with a conductivity as high as 10-1 S/m, their mechanical strength was compromised.

In this paper we report on new experiments designed to maintain high electrical conductivity while improving on the mechanical behavior of percolating ABS/CB nanocomposites. The experiments were aimed at controlling the processing parameters such as temperature, pressure and time during hot pressing of the mechanically mixed precursor materials. Using data obtained at the various temperature-pressure combinations used, it will be shown that similar volume percentages of carbon black and carbon nanotubes can be used to obtain equivalent conductivities, suitable for EMI shielding, while still maintaining good mechanical properties.