Time-temperature-cure process window of epoxy-vinyl ester resin for applications in liquid composite moulding processes

Abstract

In this work, a methodology is proposed to develop time–temperature-cure process window of an epoxy-vinyl ester resin using cure kinetics. The cure kinetics of a commercially available epoxy-vinyl ester resin formulated for Liquid Composite Molding (LCM) processing was studied by Differential Scanning Calorimetry (DSC) under isothermal conditions over a specific range of temperature. For isothermal curing reactions performed at 50, 60, and 70 °C, several influencing factors were evaluated using the heat evolution behavior of curing process. Several cure kinetic models were tested to describe the cure kinetics of epoxy-vinyl ester resin. Comparisons of the model solutions with our experimental data showed that the modified Kamal and Sourour three parameter model was capable of capturing both the degree of cure and the curing rate qualitatively and quantitatively. The model parameters were evaluated by a non-linear multiple regression method and the temperature dependence of the kinetic rate constants thus obtained has been determined by fitting to the Arrhenius equation. The model parameters were extrapolated to operate able time- temperature profiles and resin cure evolution behavior was determined.