Epoxide homopolymerization epoxy systems

The nature of the cure reactions in these epoxies can be confirmed by monitoring the epoxide consumption via near infra-red spectroscopy for a series of epoxide-amine mixtures containing a range of amine contents. A plot of % epoxide consumption vs. amine concentration for DGEBA-T403 epoxies is illustrated in Fig. 2. This plot confirms that the DGEBA-T403 epoxy system forms exclusively from epoxide-amine addition reactions, because (i) 100% epoxide consumption is attained at the stoichiometric amine concentration associated with exclusive epoxide-amine addition cure reactions and (ii) extrapolation of this plot to zero amine content indicates there is no epoxide consumption i.e. there are no epoxide homopolymerization reactions. 

Imidazoles are added to epoxy systems to catalyze the homopolymerization of epoxide groups (polyetherification), but unmodified imidazoles begin to react when mixed with epoxides (cure occurs slowly at room temperature), making them unsuitable for use in one-pot compositions. Transition metals have been used to prepare complexes of imidazoles that react very slowly at room temperature. 

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