TTT cure diagram for an epoxy system diglycidyl ether of bisphenol A/1,2 diamine cyclohexane/calcium carbonate filler

Curing reactions of the epoxy system consisting of a diglycidyl ether of bisphenol A (BADGE n=0); 1,2 diaminecyclohexane (DCH); and calcium carbonate filler were studied to calculate a time–temperature-transformation (TTT) isothermal cure diagram for this system. Gel times were measured as a function of temperature using two experimental methods: solubility test and dynamic mechanical analysis (DMA). The results obtained are in fair agreement with that obtained for the two component system BADGE n=0/1,2 DCH. Vitrification times for the three component system was higher than those obtained for the system BADGE n=0/1,2 DCH and the conversions achieved were very close to maximum values. The activation energy for the overall polymerization reaction was calculated from the gel times obtained using the two above mentioned methods: solubility test (57.12 kJ/mol) and DMA (54.12 kJ/mol). These values are of the same order than those obtained for the two component epoxy system. It was established that the addition of calcium carbonate filler avoids the appearance of physical aging, thus making easier both the determination of glass transition temperatures, and the calculation of the TTT diagram.