Model studies on the cross-linking of epoxy resins with amines at room temperature

The curing mechanisms of bisphenol-A epoxide with amines have been investigated using a cresol epoxide and mono- and diamines in model reactions which do not lead to polymers. With all amines the reaction begins with the formation of beta-aminoalcohols, and the reaction product contains secondary amino groups of remarkably lower nucleophilicity. Thus it is concluded that the formation of a linear polymer is always the first step in the curing of epoxide resins with amines. Crosslinking by the addition of the secondory amines to the remaining epoxide will be hindered due to the immobility of the reaction partners of the first reaction. The whole curing reaction is governed by the nucleophilicity of the amines and steric effects. (IFAM