Effect of simultaneous polyaddition reaction on the curing of epoxides

Epoxy‐amine curing reactions were theoretically studied using expectation theory taking into account the different reactivities of (1) the primary and secondary amine hydrogens and (2) the secondary hydroxyl group generated when an amine reacts with an epoxy group. The curing compositions and the fractional conversions at the gel point were computed. Generally the hydroxyl groups react slower than the amines and user these conditions, the reactivity of the OH group has a significant effect only when there is an intial excess of epoxide over the amine. The hydroxyl activity effectively increases the functionality of the epoxides and gelation can occur where it may not be expected.