Kinetics and mechanism of esterification of epoxy resin with methacrylic acid in the presence of tertiary amines

The synthesis of vinyl ester resins V₁, V₂, and V₃ was carried out using bisphenol-A based epoxy resin and methacrylic acid in the presence of triethyl-, tripropyl-, and tributyl-amines, respectively. The reaction follows first-order kinetics. The interaction between acid and amine was investigated by IR spectroscopy which shows absorptions corresponding to the formation of activated acid–catalyst complex. The specific rate constants, calculated by regression analysis, were found to obey an Arrhenius expression. The kinetic and thermodynamic parameters: activation energy, frequency factor, entropy, enthalpy, and free energy revealed that the reaction was spontaneous and irreversible with a highly ordered activated complex. The activation energy of the esterification of epoxy resin in the presence of tertiary amines increases in order V₁ < V₂ < V₃. The experimental results were explained by proposing a reaction mechanism and deriving the rate equation. © 2005 Wiley Periodicals, Inc. Adv Polym Techn 24:1–13, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20026