Kinetic and thermodynamic studies of the isothermal curing reaction of the diglycidyl ether of bisphenol A/Ni(II) chelate system

Abstract

AbstractThe curing reaction of a system consisting of a diglycidyl ether of bisphenol A (DGEBA) based epoxy and a new inorganic complex curing agent based on Ni(II) chelate with ethylendiamine (en) as a ligand was studied with an isothermal Fourier transform infrared (FTIR) technique. The hardener was prepared and characterized by means of FTIR spectroscopy, elemental analysis, and ICP–plasma techniques. The results of kinetic studies with two kinetic models, Horie et al. and Kamal, showed that the Kamal method gave the best fit to the experimental data. The overall values of the rate constants and activation energy for the DGEBA/Ni(en)3Br2 system were calculated. The activation energy of the curing process was also determined by an isoconversional method, which showed that with the progress of curing time, the activation energy increased. Further, the results obtained from thermodynamic studies give the entropy change of activation, which was more negative for the nth‐order path, whereas the activation heat of the reaction was more negative for the autocatalytic path. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1540–1547, 2005