Curing kinetics and thermal property characterization of a bisphenol-F epoxy resin and DDO system

The curing kinetics of a bisphenol-F epoxy resin (BPFER)/4,4'-diaminodiphenyl oxide (DDO) system were studied with isothermal experiments via differential scanning calorimetry. Autocatalytic behavior was shown in the first stages of the cure for the system, which was well described by the model proposed by Kamal that includes two rate constants, k(1) and k(2), and two reaction orders, m and n. The curing reaction at the later stages was practically diffusion-controlled because of the onset of gelation and vitrification. For a more precise consideration of the diffusion effect, a diffusion factor, f(alpha), was introduced into Kamal's equation. In this way, the curing kinetics were predicted well over the entire range of conversion, covering both previtrification and postvitrification stages. The glass-transition temperatures (T-g's) of the BPFER/DDO system partially isothermally cured were determined by means of torsional braid analysis, and the results showed that T-g's increased with conversion up to a constant value. The highest T-g was 376.3 K. The thermal degradation kinetics of cured BPFER were investigated with thermogravimetric analysis, which revealed two decomposition steps. (C) 2002 John Wiley & Sons, Inc. J Appl Polym Sci 83: 1586-1595, 2002.