Synergistic effect of CNT/CB hybrid mixture on the electrical properties of conductive composites

Nanocomposites are advanced engineering materials with multifunctional characteristics and numerous applications in the packaging, automotive, construction, and energy sectors. In this work, the effects of nanofiller geometry on the processing behavior, interfacial interaction, and electrical percolation behaviors of melt-mixed polystyrene (PS) nanocomposites were investigated. This paper also reports on the synergistic influence of incorporating multi-nanofiller mixture on the electrical resistivity of polymer nanocomposites. Two nanofillers of different geometries and electrical conductivities, namely carbon nanotubes (CNTs) and high-structure carbon black (CB), were used to prepare the nanocomposites. CNTs have a rod-like (1D) shape, whereas CB is characterized by an irregular-branched shape. Because CNTs have higher aspect ratio and electrical conductivity than CB, the CNT-based composites exhibited lower electrical resistivity and electrical percolation threshold than the CB-based composites. The analysis of the percolation behaviors showed that the network formation in the CNT/PS and CB/PS composites can be attributed to the kinetic percolation rather than the statistical percolation. Most interestingly, the CNT:CB/PS composites with a CNT:CB mass ratio of 75:25 showed higher electrical conductivity than the CNT-based and the CB-based composites, revealing a synergetic effect on the electrical properties at this nanofiller ratio.