Tuning by process of the electrical percolation behavior of multiwalled carbon nanotubes/epoxy composites

Electrical properties of carbon nanotubes polymer composites are strictly related not only to the content of the conductive nanoparticles, but also to their network morphology forming within the hosting matrix. The percolation phenomenon is strongly depending on processing conditions and for many composite systems the percolation threshold has been found to be well below the statistical one. In this work, epoxy composites at different multiwalled nanotubes (MWNT) contents have been produced using sonication as dispersion technique. Different electrical properties have been induced in the composites at the same MWNTs content by varying sonication time and curing temperature and the dependence of the percolation phenomenon on the two process parameters has been studied. The electrical conductivity shows an enhancement of even six orders of magnitude for the same MWNTs concentration upon an increase of curing temperature.