The influence of interfaces and water uptake on the dielectric response of epoxy-cubic boron nitride composites

In this study, epoxy-cubic boron nitride composites are fabricated, and their dielectric response is investigated. They exhibit the same trend as epoxy composites reinforced with other filler types. Thus, at low filler concentrations, they exhibit a lower relative permittivity than neat epoxy. As the fill grade further increases, the relative permittivity of the composites increases as well. It is suggested that two competing mechanisms, namely polymer re-organization and water uptake, mainly determine the dielectric response of epoxy composites. The former is related to the decrease while the latter to the increase of the relative permittivity. The experimental results clearly verify that water uptake strongly depends on the filler concentration and not only affects the dielectric response of epoxy composites but also it is one of the main mechanisms which dictate their dielectric behavior.