A new approach to modeling the cure kinetics of epoxy/amine thermosetting resins. 2. Application to a typical system based on bis[4-(diglycidylamino)phenyl]methane and bis(4-aminophenyl) sulfone

Abstract

Differential scanning calorimetry in dynamic and isothermal modes was used to study the cure kinetics of the commercial epoxy system Narmco 5208, whose main components are bis[4-(diglycidylamino)phenyljmethane and bis(4-aminophenyl) sulfone. The data were analyzed in terms of a new mechanistic approach described in the preceding paper. The treatment explicitly takes into account both the epoxideamine reactions and the subsequent etherification reaction. The kinetics can be completely described in terms of three rate constants, which obey the Arrhenius relationship. Excellent agreement with the experimental data is obtained if the etherification reaction is assumed to be first order with respect to the concentrations of epoxide groups, hydroxyl groups, and the tertiary amine groups formed in the epoxide-amine reaction. This model applies over the whole range of conversion up to the point where the resin vitrifies and the reaction becomes diffusion-controlled. The effect of the diffusion control is described very well by an approach based on simple equations proposed in the literature. Altogether, the model allows accurate prediction of the degree of conversion over the whole range of cure and over the temperature range 160-200°C , which covers the usual curing conditions. Although the rate constants derived are specific to Narmco 5208, the model itself is generally applicable to other epoxy amine systems.

Epoxy-based Carbon Nanotubes Reinforced Composites

“…Previous studies showed autocatalytic mechanism for TGDDM/DDS composite curing [Cole et al, 1991;Nam et al, 1993;Barral et al, 1998]. The present study revealed the accelerating effect of MWCNTs on the epoxy curing reaction during the initial stage (autocatalytic nature), which decreased with increasing amounts of CNTs.…”

Modeling the Cure of an Epoxy‐Amine Resin with Bisphenol A as an External Catalyst

“…From a mechanistic approach, few authors have extended the Horie treatment to include these side reactions. [13][14][15][16] To improve the fundamental knowledge of epoxy-amine cure, mechanistic reaction models were developed based on the existence of different termolecular and tetramolecular transition complexes [2,3,[17][18][19] whose formation has been shown [18] or supposed [3] to be the rate determining step. The first step includes the formation of bimolecular donor-acceptor complexes (Scheme 1).…”

Diffusion control on the cure kinetics of DGEBA with ethylenediamines

“…The model loses it relation with the theoretical argument on which it is based, i.e., the free volume change in the system. What is more, the determination of glass transitions in highly cross-linked polymers is sometimes difficult The second approach is the application of semiempirical methods [6,7], which relate diffusion-controlled reaction rates with chemical reaction rate by exponential functions of α − α C , where α C is a critical conversion corresponding to the beginning of the diffusion control. α C is difficul to evaluate with precision, so the diffusion control stage remains unsolved.…”