Gamma radiation impact on dielectrics and RH sensitivity of nylon–carbon–GNP–epoxy composites

Abstract

Composites of carbon–graphene nanoplatelets (GNP) epoxy with nylon‐66 interleaving were fabricated and investigated to understand the impact of γ‐irradiation on their dielectrics and relative humidity (RH) sensitivity by capacitance and water absorption measurements. The moisture sensitivity was investigated by measuring memory effect (hysteresis) and response time of the capacitance. Composites were γ‐irradiated at doses of 1000 and 3000 kGy and studied by the same set of measurements. X‐ray diffraction analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy were used to understand the impact of γ‐irradiation on the morphology and surface roughness of the composites. Results of these measurements suggest that 3000‐kGy dose γ‐irradiation produces good chain scission and cross‐linking, resulting in reduced water absorption and a 360% increase in capacitance values. The sensitivity of capacitance for 3000‐kGy γ‐irradiated composite was found to be highest at 40 pF/%RH, and hysteresis was 1.8% RH and not observed in non‐irradiated composites. Based on these observations, it seems that 3000‐kGy γ‐irradiated composite could be a potential candidate for moisture content diagnostics during condition monitoring of the carbon–epoxy structures in several industrial applications and needs to be further investigated.Highlights Composites of carbon–GNP epoxy with nylon‐66 interleaving were γ‐irradiated. 3000‐kGy dose γ‐irradiated composites exhibit 360% increase in capacitance. Sensitivity and hysteresis were higher than those of 1000‐kGy and non‐irradiated samples. Good chain scission and cross‐linking resulted in reduced water absorption.