Étude diélectrique de systèmes époxy-amine. 2. Cinétique chimique et conductivité

Abstract

Three reactive epoxy-amine systems based on diglycidyl ether of bisphenol A (DGEBA) with 4,4′-diaminodiphenylsulfone (DDS), 4,4′-methylenebis [3-chloro 2,6-diethylaniline] (MCDEA) and 4,4′-methylenebis [2,6-diethylaniline] (MDEA), were studied during isothermal curings at 140° and 160°C. The experimental procedure allowed elimination of time variable and direct expression of the conductivity, σ, in terms of conversion, x, and of glass transition temperature, T g. The conductivities, σ 0, of the initial monomer mixture and, σ ∞, of the fully cured network are measured. It is found that: •the glass transition temperature, T g, versus conversion, x, curves follows the equation of Di Benedetto modified by Pascault and Williams; •there exists a linear relation between log σ/log σ 0 and T g. So, it is possible to predict both kinetic and dielectric behaviors of these epoxy-amine systems by the knowledge of T g0, Δ C p0 and σ 0, respectively glass transition temperature, heat capacity and conductivity of initial monomer mixture, T g∞, Δ C p∞, and σ ∞, respectively glass transition temperature, heat capacity and conductivity of fully cured network.