Electrical Conductivity in Polymer Blends∕ Multiwall Carbon Nanotubes

Abstract

Carbon nanotubes (CNT) based polymer composites have emerged as the future multifunctional materials in view of its exceptional mechanical, thermal and electrical properties. One of the major interests is to develop conductive polymer composites preferably at low concentration of CNT utilizing their high aspect ratio (L/D) for numerous applications, which include antistatic devices, capacitors and materials for EMI shielding. In this context, polymer blends have emerged as a potential candidate in lowering the percolation thresholds further by the utilization of 'double‐percolation' which arises from the synergistic improvements in blend properties associated with the co‐continuous morphology. Due to strong inter‐tube van der Waals' forces, they often tend to aggregate and uniform dispersion remains a challenge. To overcome this challenge, we exploited sodium salt of 6‐aminohexanoic acid (Na‐AHA) which was able to assist in debundlling the multiwall carbon nanotubes (MWNT) through 'cation‐π' interactions during melt‐mixing leading to percolative 'network‐like' structure of MWNT within polyamide6 (PA6) phase in co‐continuous PA6/acrylonitrile butadiene styrene (ABS) blends. The composite exhibited low electrical percolation thresholds of 0.25 wt% of MWNT, the lowest reported value in this system so far. Retention of 'network‐like structure' in the solid state with significant refinement was observed even at lower MWNT concentration in presence Na‐AHA, which was assessed through AC electrical conductivity measurements. Reactive coupling was found to be a dominant factor besides 'cation‐π' interactions in achieving low electrical percolation in PA6/ABS+MWNT composites.