Role of the particle size polydispersity in the electrical conductivity of carbon nanotube-epoxy composites

TL;DR

This paper investigates how the size distribution of carbon nanotubes affects the electrical conductivity of CNT-epoxy composites, revealing a quasiuniversal relationship linked to the average nanotube length.

Contribution

It demonstrates that the electrical conductivity depends primarily on the first moment of nanotube length distribution, challenging previous assumptions about higher moments' importance.

Findings

Conductivity is a quasiuniversal function of the average nanotube length.

Size polydispersity and clustering influence electrical transport.

The mechanism allows for controlled tuning of conductivity.

Abstract

Carbon nanotubes (CTNs) with large aspect-ratios are extensively used to establish electrical connectedness in polymer melts at very low CNT loadings. However, the CNT size polydispersity and the quality of the dispersion are still not fully understood factors that can substantially alter the desired characteristics of CNT nanocomposites. Here we demonstrate that the electrical conductivity of polydisperse CNT-epoxy composites with purposely-tailored distributions of the nanotube length L is a quasiuniversal function of the first moment of L. This finding challenges the current understanding that the conductivity depends upon higher moments of the CNT length. We explain the observed quasiuniversality by a combined effect between the particle size polydispersity and clustering. This mechanism can be exploited to achieve controlled tuning of the electrical transport in general CNT nanocomposites.