Effect of coupling agents on the dielectric properties of aluminum particles reinforced epoxy resin composites

Abstract

In this study, four kinds of coupling agents (i.e., silane KH550, silane KH560, titanate NXT-102, titanate NXT-201), were used to modify the surfaces of aluminum (Al) particles. The effects of these coupling agents on the microstructures and dielectric properties of the Al/epoxy composites were investigated by the scanning electron microscope (SEM) and dielectric analyzer. The SEM observations reveal that the use of coupling agents improved the interfacial bond strength between Al particles and epoxy resin, and decreased the voids and defects at the phase interfaces. The dielectric analysis indicate that the surface modification of Al particles had an appreciable effect on the dielectric permittivity of the composites at high filler concentration, that is, at 70 wt% Al particles (treated with silane KH560) content, the dielectric permittivity of the composites reached 34.1, as compared to 19.6 for the untreated filler reinforced one; however, the dielectric loss factors of the composites slightly decreased, and they remained at a very low level under various applied sweep frequencies despite the filler content.