An approach to reduce the percolation threshold of MWCNT in ABS/MWCNT nanocomposites through selective distribution of CNT in ABS matrix

Abstract

In this article, we demonstrate a facile route to prepare ABS/MWCNT nanocomposites with high electrical conductivity at a significantly low percolation threshold of the CNT. The strategy involves in situ co-polymerization of styrene and acrylonitrile monomers in the presence of multi-wall carbon nanotubes (MWCNT) and commercially available acrylonitrile butadiene styrene (ABS) beads. A dramatic improvement in the electrical conductivity in the nanocomposites was evident with increasing content of ABS beads at a constant CNT loading, which might be explained in terms of the formation of a continuous network structure of CNTs throughout the in situ polymerized ABS matrix. Such selective dispersion of MWCNTs results in an electrical conductivity (3.01 × 10⁻⁷ S cm⁻¹) in the nanocomposites at 30 vol% loading of ABS beads and 0.24 vol% loading of MWCNTs. An increase in electrical conductivity to 4.50 × 10⁻⁵ S cm⁻¹ was evident when the ABS bead content was increased to 60 vol% at the same loading of MWCNTs. The morphological analysis of the nanocomposites indicates selective distribution of the MWCNTs in the in situ co-polymerized ABS phase of the nanocomposites leaving the externally added ABS beads free from CNT dispersion. This leads to an increase in effective concentration of the CNTs in the in situ co-polymerized ABS phase of the nanocomposites, which in turn creates a path of MWCNTs throughout the matrix, resulting in a decrease in the percolation threshold of the nanocomposites to a lower value (0.2 vol% MWCNT).