Highly dispersible aligned multiwall carbon nanotube bundles and their optimum length for electrically conductive applications

• Highly dispersible aligned MWCNT bundles were synthesized in large quantity.
• Efficiently dispersed state of the aligned MWCNTs inside nanocomposites was observed.
• Optimum length of MWCNTs was determined for electrically conductive applications.
• Influence of MWCNTs-morphology on the conductivity of composites was elucidated.

Highly dispersible aligned multiwall carbon nanotube (MWCNT) bundles were synthesized, and then, the nanotube-based nanocomposite and ink were prepared. It was found that the aligned MWCNTs were quite easily dispersed in the matrix of low density polyethylene (LDPE) by an extrusion process, whereas the entangled nanotubes were not dispersed at all while passing through the extruder. As a result, the sheet resistance of aligned MWCNTs (2 wt%)/LDPE composite plate (103.8 Ω/□) was found to be much lower than that of the composite prepared using entangled nanotubes (109 Ω/□). It was further found that the optimum length of aligned MWCNTs for electrically conductive application is varied with the fabrication process and its parameters. The optimum length of aligned nanotubes was found to be ∼50 μm when the MWCNT/LDPE composite was prepared using a twin extruder. In contrast, the longer nanotubes showed better conductivity when the sonication was used to fabricate composite and ink.