Isothermal cure kinetics and thermodynamics of an epoxy–nickel–diamine system

A study was conducted on the cure kinetics and thermodynamics of a nickel‐containing epoxy polymer obtained by the polymerization of diglycidyl ether of bisphenol A (DGEBA) with a nickel catalyst of diethylenetriamine (Dien) under isothermal condition. The apparent activation energy (Ea) was determined for the whole conversion range by the model‐free iso‐conversional approach. Isothermal kinetic parameters were estimated using an autocatalytic cure mechanism proposed by Kamal. The model gives a good description of curing kinetics at various temperatures prior to the onset of vitrification. Using the rate constants from the kinetic analysis and transition state (TS) theory, thermodynamic parameters such as enthalpy, entropy and Gibbs free energy changes were also calculated. The thermodynamic functions were shown to be very sensitive parameters for evaluation of the cure reaction.