Low frequency dielectric analysis for understanding water absorption characteristics of epoxy nanocomposites

Abstract Nanocomposites are versatile multifunctional engineering materials. For electrical applications, diminishing water diffusion and optimization of electrical properties are challenging. Low frequency dielectric measurements are preferred for the assessment of water diffusion because of the dominant low frequency response in the presence of water. Epoxy composites with organically modified montmorillonite of 2, 5, and 7 wt% are investigated. Filler at 5 wt% is observed to be optimal, with a 28% reduction in the diffusion coefficient. Higher filler content decreases the real permittivity due to interfacial polarization, and water diffusion for 240 h reveals minimal filler dependence of real permittivity. The relaxation peak of imaginary permittivity occurs at 0.08 Hz at 5 wt%, and at higher frequencies in other composites due to changes in the filler matrix interactions and electrical conductivity. Water diffusion tends to decrease imaginary permittivity. AC conductivity is not influenced by the filler and it ranges from 10 −10 to 10 −9 S/m over 10 −4 Hz–1 kHz, and its variations with water diffusion at lower frequencies are not significant. The differences in the nanocomposites are confirmed using FTIR analysis. The multi‐core water shell model is correlated to the variations observed in the dielectric properties of the nanocomposites. The utility of low frequency dielectric analysis is demonstrated for the assessment of water diffusion. Key application areas of low frequency dielectric analysis are the estimation of water diffusion mechanisms and it is an enabler of the development of data analytics using machine learning for improving the quality of nanocomposites. Highlights 5 wt% OMMT addition offers optimal water barrier performance in epoxy composites. Surface‐modified OMMT enhances filler distribution and interfacial adhesion. Dielectric loss peaks shift to 0.08 Hz at 5 wt% filler content. AC conductivity remains stable at 10 −10 –10 −9 S/m across frequencies. Low‐frequency dielectric analysis accurately models water absorption.