Reactivite du dimethylcyanamide vis a vis des groupements o- et N-epoxyde et hydroxyle

Abstract

Several factors may affect the formation of the network of epoxy resins polycondensed with dicyandiamide, in particular: (a) the monomer functional group; (b) the relative reactivity of monomers; (c) the initial composition of the system; and (d) the reaction mechanism occurring in the molten state. The study of model reactions using monomers of low functionality enables points (b)–(d) to be examined because low molecular weight products are obtained and they can be identified by NMR, HPLC and IRFT. We have investigated the reactivities of O-epoxy, N-epoxy and hydroxyl group (mechanisms and kinetics) in the presence of dimethyl cyanamide with a series of model compounds. The results for the seven systems studied confirm the hypothesis about reaction mechanisms, proposed in the literature, and show the importance of the environment on the reactivity of the cyanamide group in the molten state and on the reaction rate.