Effect of aspect ratio and bulk density of carbon nanotube on the electrical conductivity of polycarbonate/multi‐walled carbon nanotube nanocomposites

Abstract

AbstractThis study investigated the electrical conductivity of PC/multi‐walled carbon nanotube (MWCNT) nanocomposites prepared by both compression and injection molding using three different MWCNTs. Among the three MWCNTs used, two of which have similarly low‐aspect ratio (AR) (60) but different bulk density (BD) (35 and 19 kg/m3). The third MWCNT has highest AR (150) and lowest BD (11 kg/m3) among the three MWCNTs. Our findings showed that CNTs having the lowest BD and the highest AR does not always produce the best dispersion quality and highest electrical conductivity, which is contradictory to existing studies. Among three MWCNTs, the MWCNT with lower AR (60) and a BD at the mid value (19 kg/m3) exhibited the highest electrical conductivity in injection‐molded samples. This MWCNT also exhibited the highest electrical conductivity in compression‐molded samples for MWCNT content above 2 wt%. This MWCNT provided better dispersion state than MWCNT with the highest AR (150) and lowest BD (11 kg/m3). We found that BD and AR have correlative effects in the individualization and dispersion of MWCNTs from its primary agglomerates. Lower BD can improve the ease of agglomerate disintegration during extrusion while a high‐AR beyond an optimal value can entangle and coil the MWCNTs, which can actually worsen the dispersion quality of the nanotubes.