Journal of Applied Polymer Science, Vol.66, No.7, 1377-1388, 1997
Kinetic-Study and Time-Temperature-Transformation Cure Diagram for an Epoxy-Diamine System
The different steps involved in the curing reaction of a purified ether of bisphenol A (BADGE n = 0) and 1,2-diamine cyclohexane (DCH) were studied with the objective to calculate a time-temperature-transformation (TTT) isothermal cure diagram for this system. A kinetic model proposed by Horie et al.(6) was used and compared to the experimental data. Gelation times and conversions were measured using two different methods : solubility test and dynamic mechanical analysis (DMA). Results obtained by both methods show a reasonable agreement. Differential scanning 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 model parameters and the relationship between T-g and conversion, T-g versus In time are calculated and found to agree with DSC experimental results for isothermal cure temperatures from 60 to 100 degrees C. A kinetically controlled master curve for isothermal cure is obtained by shifting T-g versus In time data to a reference temperature, T-r = 80 degrees C. The apparent activation energy was calculated from gel times measurements (12.63 kcal mol(-1) = 52.88 kJ mol(-1) from solubility test 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. : solubility test and dynamic mechanical analysis (DMA). Results obtained by both methods show a reasonable agreement. Differential scanning 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 model parameters and the relationship between T-g and conversion, T-g versus In time are calculated and found to agree with DSC experimental results for isothermal cure temperatures from 60 to 100 degrees C. A kinetically controlled master curve for isothermal cure is obtained by shifting T-g versus In time data to a reference temperature, T-r = 80 degrees C. The apparent activation energy was calculated from gel times measurements (12.63 kcal mol(-1) = 52.88 kJ mol(-1) from solubility test 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.