Dielectric spectroscopy of epoxy-based barium titanate nanocomposites: effect of temperature and humidity

Abstract

The information contained in the dielectric response of materials is useful to study the charge transport behaviour of dielectric materials at the molecular level. Therefore, in this work, broadband dielectric spectroscopy is used to measure complex permittivity of epoxy resin and its nanocomposites over a wide frequency range of 10⁻³ –10⁺⁶ Hz. Measurements are carried out at different temperatures (25–90°C) and relative humidities of 50% RH and 90% RH. Nanocomposites are prepared with as-received and surface-functionalised barium titanate (BaTiO₃) nanofillers incorporated into epoxy. Filler loading of 1–10% by volume are achieved and investigated. A detailed study of the effect of filler loading and surface functionalisation of particles before incorporation into the nanocomposite is included. It is seen that the addition of nanofillers increases both real and imaginary relative permittivity of the composite. Experiments are carried out to understand the effect of water content on epoxy and its nanocomposites. It reveals that low-frequency dispersion or quasi-DC conduction is exhibited at high humidity (90% RH) and high temperature (90°C).