Estimation of the cross-linking ratio and glass transition temperature during curing of amine-cross-linked epoxies

Abstract An estimation tool developed for the cure optimisation of carbon/epoxy prepreg has been improved to determine during a cure cycle the variation in component temperature, the cross-linking ratio, and the glass-transition temperature of the matrix. The cross-linking ratio, α , is fitted by solving by finite differences the relationship of Sourour and Kamal. The required parameters are identified with the experimental curve α = f (cure time) for partially cured samples. We have first established the exponential equations between T g and α , then determine the change in T g with the cure time by using these exponential equations and the estimation curve of α . To validate this estimation tool, a different cure temperature cycle was applied to the same prepreg and the experimental values of T g and α of partially cured samples were satisfactorily compared to the calculated values.