Electrical conduction mechanisms in percolating nanocomposites-based polyester resin reinforced multiwalled carbon nanotubes

The electrical conduction mechanisms of polyester (PES) loaded with different concentrations of multiwalled carbon nanotubes were examined over a temperature range from 300 to 400 K and a frequency range from 100 Hz to 1 MHz. Differential scanning calorimetry revealed a decrease in the glass transition temperature of the matrix with increasing MWCNT concentration. Electrical resistivity analysis identified (i) a percolation threshold at a MWCNT concentration of ϕp = 0.6 wt%, and (ii) above ϕp, a positive temperature coefficient of resistivity (PTCR) and a negative temperature coefficient of resistivity (NTCR), respectively, below and above Tg. The frequency-dependent conductivity was modelled using Jonscher’s power law. The evolution of its exponent with temperature allows for the identification of two conduction mechanisms in these nanocomposites: CBH and NSPT. Activation energy was calculated from dc conductivity, reflecting the plasticizing effect of PES as a function of MWCNT concentration.