The interaction of epoxy oligomers and isocyanates has been studied by i.r.-spectroscopy, differential thermal analysis and chemical methods. It is shown that this process involves two successive reactions viz. urethane formation followed by formation of 2-oxazolidone. The presence of a tertiary nitrogen atom in the structure of the epoxy oligomer or isocyanate, in addition to the reactions just mentioned, causes isocyanate trimerization. The structures of epoxide and isocyanate affect considerably the relative reactivity of the reagents in the formation of oxazolidones and determines the range of reaction temperatures. For their relative reactivity in the formation of oxazolidones, both the epoxides and isocyanates are arranged in the same order: aliphatic > aliphatic-alicyclic > aromatic. © 1986.
Kadurina, T. I., Prokopenko, V. A., & Omelchenko, S. I. (1986). Studies of interactions in oligomeric epoxy resin-isocyanate systems. European Polymer Journal, 22(11), 865–870. https://doi.org/10.1016/0014-3057(86)90062-5