Kinetic study and time-temperature-transformation cure diagram for an epoxy-diamine system

✍ Scribed by Lisardo Núñez; J. Taboada; F. Fraga; M. R. Núñez

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 295 KB
• Volume: 66
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19971114)66:7<1377::aid-app16>3.0.co;2-#

✦ Synopsis

The different steps involved in the curing reaction of a purified ether of bisphenol A (BADGE n Å 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, a, 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 ln time are calculated and found to agree with DSC experimental results for isothermal cure temperatures from 60 to 100ЊC.

A kinetically controlled master curve for isothermal cure is obtained by shifting T g versus ln time data to a reference temperature, T r Å 80ЊC. The apparent activation energy was calculated from gel times measurements (12.63 kcal mol 01 Å 52.88 kJ mol 01 from solubility test and 12.28 kcal mol 01 Å 51.42 kJ mol 01 from DMA measurements).

Isoconversion contours were calculated by numerical integration of the kinetic model.