The system of bisphenol-A diglyeidyl ether type epoxy resin(DGEBA)cured with 2-ethyl-4- methylimidazole(2

4-EMI)was studied by means of differential scanning ealorimetry (DSC)in isothermal mode．Analysis of DSC cures indicated that the curing reaction could be separated into two stages

the addition reaction and the catalytic polymerization

as proposed in the literatures．The catalytic polymerization reaction has an induction period which decreases with the increasing of curing temperature(Tc)．The rate constants for the catalytic polymerization stage Were calculated from DSC studies．A curing kinetic model separated into two steps by the induction period was developed based on the reaction mechanism．The model can predict part of the experimental results．but some deviations are observed at the higher values of curing degree(α)．A critical value of curing degree (α)and a diffusion factor were introduced

and a diffusion controlled curing kinetic model was developed．For the systems of various concentrations of 2

4-EMI cured in the temperature range of 90～120℃

the values of αcwere calculated．The studies show that the diffusion factors affect the curing kinetics greatly in the higher values of α．When the valHe of α is lOW

the reaction is controlled by the chemical factors

but it is eontrolled by diffusion

when α is high．The value of αcis mainly affected by the glass transition of the system．With the increase of Tc

the curing degree at the glass transition increases and thus the value of αcincreases too．