The dielectric properties of a curing epoxy/amine system have been studied from 25 to 120°C at 2.45 GHz. The epoxy resins at different extents of curing exhibit a ␥ relaxation, which can be described by the Arrhenius rate law. The relaxation is attributed to the motions of the dipolar groups associated with the crosslinking system. A simple model is proposed to represent the temperature dependence of the dielectric properties. A complete description of the evolution of the parameters during the polymerization has been obtained. The nature of the information yielded by dielectrometry on the dynamics of the system is discussed.

The dielectric properties of a curing diglycidyl ether of bisphenol A (DGEBA)/Jeffamine D-230 system have been studied over the temperature range of 20 -90°C at 2.45 GHz. It was found that, generally, both the dielectric constant and the dielectric loss factor of the system increased with temperature and decreased as the reaction proceeded. The epoxy resins at different extents of cure exhibited the ␥ relaxation, which can be described by the Arrhenius Rate Law. The relaxation is attributed to the motions of the dipolar groups associated with the reactants. The Davidson-Cole model can represent the temperature dependencies of the dielectric properties. The nature of the information yielded by dielectrometry on the dynamics of the system is discussed. The evolution of the parameters of the models during the polymerization was mainly affected by the decreasing number of the dipolar groups involved in the reaction and increasing medium viscosity. POLYM. ENG. SCI., 45:1576 -1580, 2005.

The dielectric behavior of a curing system of diglycidyl ether of bisphenol A and m-phenylenediamine has been studied over the temperature range of 20—100°C under 2.45 GHz microwave radiation. The dielectric constant and the dielectric loss factor of the system increase as temperature increases while they decrease as the curing reaction progresses. The epoxy resins at different extents of cure exhibit the g relaxation, which can be described by the Arrhenius rate law. The relaxation is attributed to the motions of the dipolar groups associated with the crosslinking system. The Davidson—Cole model is used to represent the temperature dependency of the dielectric properties.

This paper presents a self-consistent 3D marching-in-time multiphysics model, which includes electromagnetic field distribution, microwave power absorption, heat transfer, and polymer curing kinetics. Temperature-and cure-dependent permittivity and curing kinetics for DGEBA/DDS based on experimental data are explicitly included in the model. An edgebased finite element method (FEM) is implemented for the electromagnetic model, whereas node-based FEM is used in the heat transfer model. The numerical results can be used to determine the time-dependent temperature distribution and curing profile across the polymer sample, as well as the electromagnetic field distribution within the cavity applicator. The numerical results are compared with the measured data and a good agreement is achieved.

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