Cure kinetics of an epoxy-rich/anhydride/imidazole system

Cure kinetics of an epoxy-rich/anhydride/imidazole system was studied by means of differential scanning calorimetry(DSC) and fourier-transform infrared spectroscopy(FT-IR). Two exothermic peaks appeared on a DSC thermogram, indicating that main esterification and competitive etherification reactions take place in an uncured sample. During isothermal curing of the sample, fast esterification occurs first, followed by slow etherification. Kinetic parameters such as activation energy (E-a), pre-exponential factor(A), rate constant (k) and reaction order (n) were determined for both esterification and etherification from the variation of DSC thermograms. Reaction order was also determined for functional groups, epoxide and anhydride, from FT-IR spectra during isothermal cure. Kissinger and fractional life methods were employed to determine the kinetic parameters in this study.