Effect of Frequency Variation on the Dielectric Permittivity of an Epoxy-Anhydride Resin System Containing Various Metal Acetylacetonate Accelerators

The effect of small amounts of metal ion dopants on the dielectric permittivity (i.e., dielectric constant and dissipation factor) of an anhydride-cured epoxy resin has been investigated. The evaluation was carried out using 10 different metal acetylacetonate additives; the permittivity of the cured resin was measured from 25 to 150°C over a frequency range of 60 to 105 Hz. Although the trends observed with the dielectric constant (i.e., with increasing frequency and temperature) were close to what was expected, the changes in dissipation factor showed some interesting features. Interaction effects between the epoxy-anhydride polymer chain segments and the metal ion by-products, derived from the thermal dissociation of metal acetylacetonates, are suggested as being mainly responsible for the observed effects.