Kinetics of epoxide resins formation from epichlorohydrin and bisphenol‐A

Abstract The kinetics of formation of epoxide resins based on epichlorohydrin and bisphenol‐A via synthesis with one‐ or two‐step addition of alkali are considered. The kinetics of the reaction were studied by taking into account the consumption of the alkali added and the change of molecular mass and epoxide value of epoxide oligomers. The results obtained are satisfactorily explained within the framework of a model containing the following postulates: all the alkali is bound as phenolate ions; all phenolic groups are of equal reactivity; the reactivity of epichlorohydrin is higher than that of glycidyl ethers; the stage of dehydrochlorination of chlorohydrin ethers in the synthesis with one‐step addition of alkali is rapid and does not limit the process; the first stage of the two‐step synthesis is the formation of chlorohydrin ethers and the second stage their consumption. The factors leading to differences between the experimentally obtained parameters of the resulting epoxide resins (molecular weight, epoxide value) and their calculated values are discussed. The synthesis of epoxide resins with two‐step alkali addition is shown to possess certain advantages over the one‐step process.