KINETIC-STUDY AND TIME-TEMPERATURE-TRANSFORMATION CURE DIAGRAM FOR ANEPOXY-DIAMINE SYSTEM

The different steps involved in the curing reaction of a purified ethe r of bisphenol A (BADGE n = 0) and 1,2-diamine cyclohexane (DCH) were studied with the objective to calculate a time-temperature-transformat ion (TTT) isothermal cure diagram for this system. A kinetic model pro posed by Horie et al.(6) was used and compared to the experimental dat a. Gelation times and conversions were measured using two different me thods: solubility test and dynamic mechanical analysis (DMA). Results obtained by both methods show a reasonable agreement. Differential sca nning calorimetry (DSC) data show a one-to-one relationship between T- g and fractional conversion, ct, independent of cure temperature. As a consequence, T-g can be used as a measure of conversion. Using the mo del parameters and the relationship between T-g and conversion, T-g ve rsus In time are calculated and found to agree with DSC experimental r esults for isothermal cure temperatures from 60 to 100 degrees C. A ki netically controlled master curve for isothermal cure is obtained by s hifting T-g versus In time data to a reference temperature, T-r = 80 d egrees C. The apparent activation energy was calculated from gel times measurements (12.63 kcal mol(-1) = 52.88 kJ mol(-1) from solubility t est and 12.28 kcal mol(-1) = 51.42 kJ mol(-1) from DMA measurements). Isoconversion contours were calculated by numerical integration of the kinetic model. (C) 1997 John Wiley & Sons, Inc.