Thermal degradation of bisphenol a type novolac epoxy resin cured with 4,4′-diaminodiphenyl sulfone

The curing reaction of bisphenol A type novolac epoxy resin (bis-ANER) with 4,4'-diaminodiphenyl sulfone (DDS) was investigated with Fourier-transform infrared (FTIR) spectroscopy. It was found that the obvious structure changes involve the disappearance of epoxide groups and increase of hydroxyls. Thermal degradation of the bis-ANER/DDS network was studied with thermogravimetry in both dynamic air and nitrogen atmospheres. The degradation takes place in two steps in air but in only one step in nitrogen. FTIR measurement was carried out to identify the changes in the structure during the degradation at different steps. In addition, the thermal degradation reaction mechanism of bis-ANER/DDS with the Coats-Redfern method showed that the kinetic model function of the thermal degradation obeys the Avrami-Erofeev model equation, that is, g (alpha) = [-ln(1 - alpha)](2/3) .