Evidences of interphase formation and concomitant change in the dielectric properties of epoxy-alumina nanocomposites

Abstract

This work unravels and sheds light on interphase formation in epoxy alumina nanocomposites. To probe interphase and its affiliation with dielectric properties, three kinds of samples are investigated viz. neat epoxy, nanocomposites (using surface treated nanofillers), and nanocomposites (with untreated nanofillers). Characteristics information received from thermogravimetric analysis and dielectric properties measurements insinuates a change in chemistry and molecular mobility at the filler matrix interfaces. Using chemical structure of different constituent phases and FTIR spectroscopic analysis a chemical interactive model is presented to elicit interphase formation in composites. The impact of interfacial interaction on long term performance of the nanodielectrics is examined by conducting endurance tests under divergent ac stress. Nanocomposites exhibit a clear superior erosion resistance over the neat polymer. Under the application of cyclic non uniform ac stress, progressive erosion is likely to initiate and grow from high stress regions. Nanofillers may act as an obstacle and force the eroded channels to move through a zig-zag path. Additionally, surface treated nanofillers owing to their strong chemical bonding with polymer matrix expected to retard damage process by alleviating fatigue and distributing electromechanical stress between filler and polymer matrix. The results of this study show compelling evidence of interphases and their prominence on dielectric properties. Moreover, this study provides an intellectual foundation to vivify how engineering the chemistry of the interfaces may help in designing nanodielectrics with enhanced functionalities. © 2020 Elsevier Ltd