Discontinuity of physical properties of carbon nanotube/polymer composites at the percolation threshold

Evolution of DC conductivity with double-walled carbon nanotube concentration in a polyamide 11 matrix displays the electrical percolation phenomenon. The percolation threshold is observed for this composite at 0.85 wt.%. Thermal, mechanical and dielectric manifestations of the glass transition have been investigated as a function of carbon nanotube content. Thermal and mechanical analyses have shown a depression of the glass transition temperature or its mechanical manifestation at the percolation threshold. Regarding the dielectric modulus, three distinct behaviors (below, at, and above percolation threshold) have been observed. A discussion about the interactions between the polymer matrix and the conductive fillers will be proposed to further the understanding of the discontinuity of physical properties at the percolation threshold.