Dielectric response of various partially cured epoxy nanocomposites

Abstract

Insufficient crosslinking and water uptake during fabrication or manipulation are known to affect the dielectric response of epoxies. Post thermal treatment may result in the completion of cross-linking, partial removal of water, and aging. In order to study the effect of manufacturing imprecision on dielectric response, several under-cured epoxybased nanocomposite samples with modified nanoclay fillers were investigated. In addition, the influence of silane coupling agents and the use of ultrasonic waves on the nanoclay intercalation were also studied. The structure of the samples and the extent of cross linking were characterized using X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC) respectively. It was found that surface silanization lead to improved clay intercalation and higher extent of intercalation/exfoliation. The influence of post thermal treatment on the dielectric response of the materials was investigated using Broadband Dielectric Spectroscopy (BDS). Once the samples were in a stable dielectric state, relaxation maps were performed. It was found that the samples with silanized nanoclay have the lowest activation energy and they also proved to be the “strongest” vitreous materials.