Assessment of unexplored isoconversional methods to predict epoxy-based composite curing under arbitrary thermal histories

Abstract

The mass manufacturing of composite products is hindered by long curing times, and composite manufacturers demand shorter curing cycles while keeping material properties. This requires reliable methods to predict the curing kinetics of each resin formulation. Isoconversional methods are easy to implement and able to deal with complex processes. However, scientists still limit their isoconversional predictions of curing degree to isothermal or constant heating programs. In this study, we perform combined dynamic and isothermal DSC measurements for two different commercial epoxies for aerospace applications (M18 and VTC401). Based on the isoconversional kinetic analysis, we show the feasibility of predicting the evolution of an epoxy resin cure for an arbitrary and complex temperature program using two different unexplored methods for this purpose. Because of the versatility of both prediction methods, they are especially suited to deal with actual conditions in industrial processes. The proposed approach is validated experimentally by comparing predictions against the curing degree of these epoxies during a temperature program that comprises isothermal and dynamic stages. These reliable and straightforward predictions open the door to optimize curing times and increase productivity in composites.