The unique dielectric behaviour of nanosilica epoxy composites

Nanofillers in epoxy composites sometimes results in unexpected properties. Presented in this paper are some findings on the dielectric properties of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin incorporated with surface modified nanosilica particles. 20 nm particles were used in the investigation and the results were compared with those of 100 nm silica composite. The composites were examined under infrared spectroscopy and XRD and it was found that the surface modification of the nanoparticles lead to a good hydrophobic property and made particles easier to form bonds with the resin. The measurements of the dielectric properties of the composites showed that by adding low dielectric constant nanosilica particles, the dielectric constants of the composite were notably increased as opposed to a drop as one might expect, while the dielectric losses were lowered. The increase phenomenon in dielectric constant is explained in terms of water molecules existence in the composites produced during the process.