Curing of epoxy resins. I. Statistics of curing of diepoxides with diamines

Publisher Website
Google Scholar
Abstract
The curing of epoxy resins with amine curing agents has been statistically treated as irreversible alternating polyaddition with the aid of the theory of cascade processes for cases when the polymerization of epoxy groups and cyclization are negligible. The coefficients of vectorial generating functions are obtained by solving kinetic differential equations. The solution has been carried out for the reaction of diepoxide with diamine with an independent reactivity of epoxy groups in diepoxide and amino groups in diamine, but with a different reactivity of hydrogen atoms in the primary and secondary amino group. Relationships have been derived for changes in the molecular weight averages, in the sol and gel fractions and their composition, and in the concentration of elastically active network chains as a function of conversion. The conditions for the gel point have been determined. The structural parameters depend on the ratio of the rate constants of hydrogen atoms in the primary and secondary amino group, k2/k1 = r, and on the stoichiometric ratio of functionalities. In a stoichiometrically equivalent system the critical conversion at the gel point increases from 1/2 for r → oo up to (1/2) (51/2 – 1) for r → 0. The critical stoichiometric ratio for gel formation at full conversion of (epoxide) functionalities in deficiency is < 3 or > 3 for r < 1 or r > 1, respectively.

This publication has 12 references indexed in Scilit: