Nonisothermal Cure Kinetics of DGEBA with 2,7-Diaminofluorene

Cure kinetics of diglycidyl ether of a bisphenol A-based epoxy resin (DGEBA) with 2,7-diaminofluorene (DAF) as curing agent have been studied by using nonisothermal differential scanning calorimeter (DSC). The values of apparent activation energy (E,) of nonisothermal cure reaction were calculated by using isoconversional and nonisoconversional methods. The E, values of the samples containing stoichiometric amount of 26 phr DAF revealed a dependence on the conversion (a) by the isoconversional method of Flynn-Wall-Ozawa (FWO). The E, values by nonisoconversional methods of Ozawa and Kissinger-Aahira-Sunose (KAS) were 58.27 and 55.68 kJ/mol, respectively. The Cure process showed that the autocatalytic behavior dominates the mechanism in the initial stages where the rate-controlling steps are located, but becomes diffusion-controlled in the final stage. Techniques of predicting isothermal cure time from nonisothermal kinetic parameters by ASTM and Vyazovkin methods were used for the cure reaction of DGEBA/DAF system. Thermal stability of the cured resin was also determined by using thermogravimetry analysis (TGA). (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 1311-1318, 2009