Carbon black-containing interpenetrating polymer networks based on unsaturated polyester/epoxy II. Thermal degradation behavior and kinetic analysis

Carbon black flame retardants were chosen to improve the flame resistance of interpenetrating polymer networks based on unsaturated polyester/epoxy due to the expansion of carbon black at elevated temperatures. Thermal degradation behaviour and kinetic parameters of this system were analysed by conventional and modulated thermogravimetric analysis (MTGA). It was found that the epoxy and polyester components decomposed individually in the polymer network. Furthermore, the activation energy calculated from the Ozawa method is somewhat lower than that of MTGA method. This implies that the decomposition reaction is not a single reaction. Moreover, the activation energy of decomposition increased as carbon black flame retardants were added. The curves of activation energy versus residual mass varied in shape and position as the carbon black flame retardants were added. This indicates that the decomposition mechanism of carbon black-containing IPNs was different from that of the pristine IPNs. (C) 2002 Elsevier Science Ltd. All rights reserved.