Impact of Current and Temperature on Extremely Low Loading Epoxy-CNT Conductive Composites

Abstract

Carbon nanotube (CNT) conductive composites have attracted significant attention for their potential use in applications such as electrostatic dissipation and/or electromagnetic interference shielding. The focus of this work is to evaluate resistivity trends of extremely low loading (<0.1 wt%) epoxy-CNT composites that lack a connected CNT network, but still present electrical conductivity values appropriate for those uses. The impact of current, temperature, and cycle life on electrical properties are here identified and tied to possible performance limits. At extremely low loadings, the CNT content is not sufficient to form a completely interconnected grid, thus, electrons must travel through insulating media. While still in the semi-conductor range, resistivity values are observed to decrease with increasing direct current and demonstrate a non-ohmic behavior. CNT epoxy composites were subjected to elevated currents and/or temperatures over diverse periods of time to examine impacts on resistivity. Microstructural analyses of composite samples were conducted to observe signs of damage for specimens taken to extreme temperatures/currents. An understanding of the electrical conductivity characteristics of extremely low loading epoxy-CNT composites and their failure mechanisms will aid in understanding risks associated with their use in challenging environments that may include high temperatures, high currents, and/or high frequencies.

CNT Conductive Epoxy Composite Metamaterials: Design, Fabrication, and Characterization

“…It was found that above 0.10% CNT loading, a continuous percolation network is formed, with the concurrent dramatic increase in conductivity [33]. Subsequent work showed that below 0.10% the mechanism of conduction is dominated by a capacitive-like behavior [36]. Similar findings were published by others providing a proof of concept that CNT conductive composites, even at very low CNT loadings, have potential for EMI applications [32,34,[37][38][39].…”

Graphene nanoplatelet, multiwall carbon nanotube, and hybrid multiwall carbon nanotube–graphene nanoplatelet epoxy nanocomposites as strain sensing coatings

“…Figure 9(b) shows the variation of electrical resistance as function of temperature. It is known that the electrical resistivity of polymer nanocomposites is affected by temperature, 57 but the question is still unsolved since some authors have experienced a reduction of resistance increasing temperature, 58 while some others have found the opposite behavior. 59 In our case, all the formulations show an increase of electrical resistance increasing the temperature.…”

Introduction of Rare-Earth Oxide Nanoparticles in CNT-Based Nanocomposites for Improved Detection of Underlying CNT Network

“…This current dependence with increasing current application is ascribed to temperature increases due to resistive heating and irreversibility in the conductive path within the composite. Further discussion can be found in [ 1 ]. Notably, a reduction in resistivity (increased conductivity) is a positive attribute for the proposed applications.…”

“…Nanoscale composites utilizing carbon nanotube (CNT) filler allow for significant reductions in resistivity of an otherwise highly insulating matrix material while requiring extremely low CNT loadings [ 1 ]. These improved conductivities result in an attractive material with extensive applications in diverse industries, but particularly for electrostatic discharge (ESD) and electromagnetic interference (EMI) prevention [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ].…”