Influence of the stoichiometry of epoxy-cyanate systems (non-catalyzed and catalyzed) on molten state reactivity

Based on an FT-IR and ¹³C-NMR spectroscopic study using model compounds, we previously proposed an epoxy-cyanate coreaction path in the molten state, by identifying all chemical species and their role in the reaction mixture. These data were then applied to difunctional systems involving diglycidyl ether of bisphenol A (DGEBA) and bisphenol A dicyanate (BADCy), with mixtures prepared in different epoxy/cyanate ratios. Using FT-IR and solid state ¹³C-NMR spectroscopic analyses, we show the effect of epoxy group concentration on the final structure of the system. We were able to show that epoxy functions react on the triazine rings formed in the first step of homopolymerization of cyanates, and that the structure of the final system depends on their initial concentration. In addition, a study of difunctional systems for identical cyanate-epoxy stoichiometry was undertaken in the presence of anionic (imidazole) and metallic (AcAcCu and AcAcCr) catalysts in order to determine their effect on the reactivity of the two monomers and on the structure of the final system. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3101–3115, 1997