A KINETIC SCHEME FOR ANHYDRIDE CURING OF DIGLYCIDYL ESTER WITH TERTIARY AMINE AS CATALYST

A kinetic model has been developed on the basis of reaction mechanisms proposed for the anhydride curing of diepoxides, using tertiary amine as catalyst. The model has been tested for the cure reaction of a diglycidylester model compound, bis-(2,3-epoxypropyl)-1,3-benzenedicarboxylate, with hexahydrophthalic anhydride as the curing agent and benzyldimethylamine as the catalyst, over the temperature range 100-120-degrees-C, the rate being measured by means of differential scanning calorimetry, using an isothermal approach. The rate expressions derived for the model are half order and first order, with respect to reacted and unreacted functional groups, respectively, in the initial stage. For the later stage of curing, up to the point of vitrification, the model indicates a 1.5 order with respect to the unreacted functional groups. These are in good agreement with the kinetic orders of 0.5 and 1.5, with respect to reacted and unreacted functional groups, respectively, reported earlier from a phenomenological approach for the whole range of curing prior to the onset of vitrification. (C) 1993 John Wiley & Sons, Inc.