Influence of selective dispersion of MWCNT on electrical percolation of in-situ polymerized high-impact polystyrene/MWCNT nanocomposites

Abstract

This work demonstrates a simple method to develop highly conducting high impact polystyrene (HIPS)/multiwall carbon nanotube (MWCNT) nanocomposites through selective dispersion of MWCNT in HIPS matrix. The method involves in-situ polymerization of polybutadiene containing styrene monomer in the presence of HIPS beads and MWCNT. A significantly lower percolation threshold value than ever reported for HIPS/MWCNT systems was obtained using unmodified unaligned MWCNTs. With the increase in HIPS bead content (at a particular MWCNT loading) in the HIPS/MWCNT nanocomposites, the conductivity value was increased, suggesting that the presence of HIPS beads acted as excluded volume that decreased the percolation threshold. An increase in electrical conductivity from 1.91•10–7 to 1.15•10–5 S/cm was evident, when the HIPS bead content was increased from 30 to 60 wt% at a constant loading of MWCNT (i.e. 0.6 wt%). The morphological investigation of the HIPS/MWCNT nanocomposites revealed that, the MWCNTs were selectively dispersed in the in-situ polymerized HIPS region, outside the HIPS beads, which resulted in the lowering of the percolation threshold to a lower value of 0.54 wt%. The morphology and electrical properties of the nanocomposites have been discussed in detail in the manuscript.

Keywords

• Polymer composites
• Nanocomposites
• HIPS
• Percolation threshold
• Conductivity