Strain and Dispersion Dependence of High Frequency Electromagnetic Properties of Carbon Nanotube/Epoxy Nanocomposites

Abstract

An experimental setup and data reduction method has been developed for noninvasive high frequency electromagnetic impedance measurements of carbon nanotube (CNT)/epoxy nanocomposites. Using time domain reflectometry and parallel plate transmission lines, dielectric properties can be measured with the specimen under tensile loading. Good dispersion and addition of CNTs lead to an increase in high frequency dielectric constant of the nanocomposites. A strong strain dependence of the impedance is observed for the well dispersed nanocomposite while the baseline epoxy showed no strain dependence. A mechanism, based on an increase in CNT-CNT tunneling capacitance with applied tensile strain has been suggested. This research is expected to introduce a noninvasive characterization technique for studying electromagnetic properties of conductive nanocomposites.