A Study on Curing Behavior of Epoxy Resin by Model-free Methods

The isoconversional methods have been widely used to study the kinetics of chemical reactions or physical transitions of polymers based on thermaldata and use of these methods has allowed important conclusions on the mechanisms of these transformations to be drawn. However, thedifferences in the activation energy (Ea) valuesdetermined from differential and integral isoconversional methods have often been noticed. For non-isothermal data, the integral methods proposed by Flynn–Wall-Ozawa (FWO), [1] and Kissinger–Akahira– Sunone (KAS) are widely usedby researcher [2, 3]. The methods of KAS andFWO are described by Eqs. (1) and (2), respectively: According to the method of KAS, the activationenergy can be obtained from the maximum reaction rate, where d(d α /dt)/dt is zero at a constant-heating rate condition. Based on FWOequation, however, a more accurate value of theactivation energy can be obtained by iteration or a least-squares technique to improve the linear approximation of the temperature integration term. In this study, curing kinetics of epoxy resins was studied by DSC non-isothermal. The change in theactivation energy of the curing process was then compared by the isoconversional methods of KAS and FWO.