Effect of structural properties in the electrical impedance spectrum of multi-walled carbon nanotube/graphite/polyester ternary composites

Abstract

The aim of this study is to establish a connection or correlation between the electrical and structural properties of ternary composites, which were prepared by adding multi-walled carbon nanotubes (MWCNT) and graphite (Gr) as conductive fillers to an insulating polyester matrix. The study utilized small-angle neutron scattering, infrared and Raman spectroscopy for structural characterization. Electrical measurements were conducted within a frequency range of 100 Hz to 1 MHz and a temperature range of 200–380 K. The alternating current (AC) conductivity showed a frequency dependence following Jonscher's power law. The temperature dependence of the AC conductivity suggested that the electrical conduction within the material is a thermally activated process. The temperature-dependent behavior of the direct current (DC) conductivity suggests that below and above the critical temperature, there is a pronounced positive and negative temperature coefficient of resistivity, respectively. In comparison to MWCNT/polyester or Gr/polyester composites, the percolation threshold of the MWCNT/Gr/polyester composite is much lower. Additionally, applying the Arrhenius equation to analyze the temperature dependence of DC conductivity reveals that the inclusion of MWCNT and Gr in the polyester matrix results in a decrease in activation energy.