Effect of multi-walled carbon nanotube aspect ratio on mechanical and electrical properties of epoxy-based nanocomposites

The effects of the aspect ratio of multi-walled carbon nanotube (MWNT) on the mechanical and electrical properties of epoxy/MWNT nanocomposites were studied. It was found that the MWNT aspect ratio has a significant effect on both electrical and mechanical properties of nanocomposites with significantly better properties for MWNTs of smaller diameter. The trend of the results was justified based on the mechanisms involved. A new percolation threshold concept was also introduced based on the aspect ratio of MWNTs. In addition, a correction factor for the Halpin-Tsai model was proposed which could greatly improve the theoretical predictions. The states of MWNT dispersion, bridging structure and fracture surface roughness were also investigated and a correlation was found between these features and the experimental results.