Autocatalytic cure kinetics from DSC measurements: Zero initial cure rate

Abstract

SynopsisA new, simplified technique for obtaining the kinetic parameters of an autocatalyzed cure reaction from isothermal DSC measurements is presented. The method is appropriate to reactions that have a zero initial rate and relies solely upon characteristics of the exotherm peak with no assumptions being made about the overall reaction order. This technique is illustrated by obtaining the phenomenological cure kinetics of a commercial epoxy f i l m adhesive. The derived kinetic model reproduces the measured isotherms in their entirety. In addition, the predictive capability of the model is demonstrated by comparison with an independent measurement of the adhesive's low temperature curing behavior. Glass transition temperature measurements are also made on partially cured samples and a good correlation with the degree of cure is found.

Curing behaviour of epoxy resins with a diamine bearing an azobenzene group

“…After this point the rate starts to decrease, eventually reaching zero. The maximum in the dα/dt versus time curve is reached at t ≠ 0 and it confirms the autocatalytic character of the reaction [12,20].…”

“…Kinetic characterisation of the thermoset resin is therefore of great importance in understanding the structure-property relationships in order to manufacture highperformance materials. Curing kinetics of epoxy resins can be studied with different techniques but differential scanning calorimetry (DSC) is widely used [11,12]. The curing of epoxy resins is highly exothermic.…”

Modeling the curing kinetics for a modified bismaleimide resin

“…This is commonly termed as an autocatalytic type reaction. The general phenomenological model equation that has been used in kinetic studies of autocatalytic reactions 17,18,20 can therefore be expressed by combining both types of reactions. The approach used basically separates the composite reaction into two elemental parts with one taking the form of an nth order reaction, and the other autocatalytic type reaction, as indicated by the following equation:…”

Curing kinetics of the synthesis of poly(2-hydroxyethyl methacrylate) (PHEMA) with ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent

“…Ethylene glycol dimethacrylate (EGDMA) is a frequently used ing of epoxy or unsaturated polyester resins and its parameters (k, m, and n) can be determined comonomer in the preparation of PHEMA hydrogels, 5,17 and it functions as a crosslinking from the isothermal DSC results. [20][21][22][23][24] The activation energy of the polymerization reaction can be agent in the thermosetting system. The reaction kinetics of the thermosetting polymerization, determined from the Arrhenius plot of the logarithm of rate constant (k) and the reciprocal of such as the curing of epoxy resins, [18][19][20] unsaturated polyester resins, [21][22][23][24] and some multifuncthe reaction temperature.…”