Relationship between isothermal and dynamic cure of thermosets via the isoconversion representation

This study deals with the cure of thermoset resins used in the pultrusion of fiber reinforced composites. The objective was to predict the degree of cure under nonuniform time-temperature profiles. A simple procedure using differential scanning calorimetry results was developed for predicting the degree of cure vs, time under isothermal conditions from dynamic DSC tests and vice versa. The principal feature of the procedure is the transformation of the degree of cure vs. time curves obtained under isothermal or dynamic DSC conditions into isoconversion curves as time vs. temperature or time vs. heating rate diagrams. The proposed procedure is validated with isothermal and dynamic DSC results from epoxy and polyester resin formulations used in the pultrusion of fiber reinforced composites. The agreement between predictions and experiments was very good and the extension of the procedure for predicting the cure under non-uniform temperature profiles as in pultrusion seems to be feasible.