Effect of fabrication process on electrical properties of polymer/multi-wall carbon nanotube nanocomposites

Polymer/carbon nanotubes nanocomposites were fabricated by an in situ polymerization process using multi-wall carbon nanotubes (MWNT) as filler in an epoxy polymer. Effects of curing process, mixing speed, mixing time, addition of ethanol, timing of hardener addition, etc., in the fabrication process on the electrical properties of nanocomposites have been investigated. In the fabrication process, the effective formation of macroscopic conducting network in matrix is most important to enhance the electrical properties of nanocomposites. It was found that the curing temperature and the mixing conditions are key factors in the fabrication process, which influence the formation of conducting network significantly. Therefore, careful design of these factors in the fabrication process is required to achieve high electrical performances of nanocomposites. The experimental percolation threshold of the resultant nanocomposites was around 0.1 wt%. Moreover, a statistical percolation model was built up to numerically investigate the percolation threshold. The experimental electrical conductivity increases from the percolation threshold following a percolation-like power law with the identified critical exponent t as 1.75. (C) 2008 Published by Elsevier Ltd.