Dielectric properties of a curing epoxy/amine system at microwave frequencies

Abstract

Abstract Dielectric data collected at 2.45 × 10 9 Hz has been analyzed using a mean relaxation time model over the temperature range 50 to 100°C and at extents of cure from 0 to 57% for a stoichiometric DER 332 (Dow)/DDS (Aldrich) mixture. The relaxation times thus obtained obey the Arrhenius law and tend to increase with the extent of cure. This corresponds to the more rigid nature of the molecular structure as the network forms and the dipolar relaxations become more inhibited. Decreases in the activation energy of the relaxation along with a widening of the relaxation time distribution imply that the relaxations involve ever shorter chain segments as the extent of cure increases.