Re-examination of the dielectric spectra of epoxy resins: bulk charge transport and interfacial polarization peaks

The dielectric properties of two amine cured bisphenol-A epoxy resin systems, Araldite CY1301 and Araldite CY1311 have been characterized using dielectric spectroscopy over the frequency range 1 mHz to 100 kHz. These two epoxy resin systems were chosen to allow the dielectric response to be studied from above and below the glass transition, as Araldite CY1311 is a modified version (with added plasticizer) of Araldite CY1301. The dielectric response was found to comprise both bulk and interfacial features. Above the glass transition temperature, two processes were identified, a low frequency process usually ascribed to interfacial polarization is shown to be a bulk process termed Quasi-DC (QDC) conduction and a dielectric dispersion usually taken to be a bulk process has been shown to be an interfacial effect.