A computational approach to evaluate the nonlinear and noisy DC electrical response in carbon nanotube/polymer nanocomposites near the percolation threshold

Abstract

This paper presents a percolating network model to determine the electrical behavior of carbon nanotube (CNT)/polymer nanocomposites, especially near the percolation threshold. In this extended model, we considered a voltage-dependent tunneling resistance at the CNT junctions, based on Simmons’ formulation. This assumption led to an electrical resistor network containing both linear and nonlinear resistance elements. We focused on extracting the continuous current-voltage (I-V) response of the nanocomposites through a recursive calculation to show the ability of the model to simulate the nonlinear and noisy behavior of the I-V curve in CNT/polymer systems. The effects of CNT diameter, length, concentration, and intrinsic conductance, as well as the tunneling gap at the junctions and matrix dielectric constant, were also investigated and discussed. Our results revealed that the nonlinearity in I-V curves near the percolation threshold is related to the voltage-dependent nature of the tunneling resistance. The number of junctions and equivalent CNT length in the percolation pathway are two effective parameters controlling the electrical behavior of CNT/polymer nanocomposites. The results obtained are also in good agreement with our previous experimental data on CNT/epoxy nanocomposite and confirmed that the proposed model can efficiently predict the I-V characteristic curves for CNT/polymer composites.