Dielectric characterization of a nanostructured polymer microcomposite and its constituents

The frequency and temperature dependence of permittivity and dielectric loss is examined between 0.01 Hz and 1.0 MHz in the range from -50degC to 130degC of a nanostructured composite in an epoxy matrix and compared with that of its constituents (60% quartz and 0.45 % nanoclay by weight). For quartz, which is in powdered form, the variation of permittivity is found to be almost linear with frequency while for nanoclay it exhibits a pronounced increase with decreasing frequency and increasing temperature. In epoxy, the dissipation factor peak magnitude at 10 kHz and 40degC decreases as it shifts to lower frequencies with falling temperature as opposed to that of quartz for which the dielectric losses rise with increasing temperature as the frequency is reduced. When the behavior of the entire nanostructured polymer microcomposite is examined, it is found to exhibit dielectric loss frequency response characteristics similar to that of the microcomposite epoxy-quartz compound without nanoclays, with a marked decrease of dielectric loss with decreasing frequency. Evidently, even a miniscule amount of the incorporated nanoclay (0.45 % by weight) exerts a pronounced effect upon the behavior of the microcomposite. The possibility of a number of dielectric loss mechanisms are considered to account for the observed behavior.