Simultaneous use of physical and chemical dispersants for electrical conductivity enhancement in polyamide 6/carbon nanotube/conductive carbon black hybrid nanocomposites

Polyamide 6 (PA6)/carbon nanotube (CNT)/conductive carbon black (CCB) nanocomposites with the incorporation of physical and chemical dispersants were prepared via melt blending method to examine the synergistic enhancement of electrical conductivity. Investigation of modified CNT with octadecyl triphenyl phosphonium chloride (OTPC-CNT) as physical dispersant was performed by Fourier transform infrared, nuclear magnetic resonance, Raman spectroscopy, and thermogravimetric analysis. Morphological, electrical, rheological, and mechanical properties of PA6/CNT/CCB nanocomposites were examined by field emission scanning electron microscopy, transmission electron microscopy, digital insulation tester, oscillatory shear rheometer, tensile test, and impact test. The results showed that by the incorporation of physical (OTPC) and chemical (RPS 1005) dispersants to a compound containing 2.5 wt.% CNT and 5 wt.% CCB, electrical conductivity was improved 9 orders of magnitude (S cm−1) compared to those of samples without any dispersants and 6 orders of magnitude compared to those of samples containing 2.5 wt.% CNT and physical dispersants. These results illustrate that by simultaneous incorporation of two different dispersants, it is possible to form a 3D conductive network in such nanocomposites and thus achieve a synergistic enhancement of electrical conductivity. The novelty of this study lies in the simultaneous incorporation of physical and chemical dispersants that lead to desired electrical conductivity without sacrificing mechanical properties besides economical advantage of production. This result is due to the remarkable effect of physical dispersants in improving electrical conductivity along with the low cost of chemical dispersants.