Curing reactions of a three-component system consisting of an epoxy resin diglycidyl ether of bisphenol A (DGEBA n = 0), 1,2-diaminecyclohexane as curing agent, and vinylcyclohexene dioxide as a reactive diluent were studied to calculate a time-temperature-transformation isothermal cure diagram for this system. Differential scanning calorimetry (DSC) was used to calculate the vitrification times. DSC data show a one-to-one relationship between T-g and fractional conversion alpha, independent of cure temperature. As a consequence, T-g can be used as a measure of conversion. The activation energy for the polymerization overall reaction was calculated from the gel times obtained using the solubility test (58.5 +/- 1.3 kJ/mol). This value was similar to the results obtained for other similar epoxy systems. (C) 2004 Wiley Periodicals, Inc.