Thermal degradation of nadic methyl anhydride‐crosslinked novolac epoxy resin

The physicochemical high-temperature reactions of a nadic methyl anhydride-cross-linked novolac epoxy resin were investigated by means of differential thermal analysis, thermogravimetric analysis, and by other analytical procedures. The thermogravimetric study revealed that decomposition involving weight loss occurred in two stages. Chemical analysis showed that the major gaseous products formed during weight loss were 2-methylcyclopentadiene, carbon dioxide, and carbon monoxide. The formation of a fine mist of solid particles was observed during the second stage of degradation. Changing various experimental parameters affected the degradation processes. The kinetics of degradation were also investigated. The method of Freeman and Carroll was used to find that a zero-order rate law was followed at the beginning of both first and second stages of reaction. The activation energy associated with the major portion of the first stage of weight loss was 15 kcal/mole. There was good agreement between the observed reaction rates and the reaction rates calculated from a theoretical model which depended on desorption as the rate-controlling step. The activation energy for the beginning of the second stage of weight loss was 24 kcal/mole. By using DTA, the heat of exothermal reaction during this latter phase of decomposition was evaluated as 65 cal/g.