Thermooxidative degradation of compositions based on an epoxy oligomer

The work is devoted to studying the nonisothermal thermooxidative degradation of the composition of an epoxy oligomer cured with 4,4-diaminodiphenyl sulfone in a stoichiometric ratio of 30 wt % hardener per 70 wt % oligomer. The relationship between the structure of the composition and the kinetic parameters of the thermooxidation is established. The network structure was varied by changing the temperature and curing time. Specific features of the mechanism and kinetics of the nonisothermal degradation epoxyamine polymer are determined using the thermoanalytical method, namely, differential scanning calorimetry, and analysis of the oxidation products. The composition of the products, the values of the activation energy and preexponential factor for the reactions occurring in the nonisothermal mode at different rates of heating of samples with different structures of the network, showed that their mechanism is controlled by a time-temperature superposition. The rate of heating of the sample determines the participation of bonds of internodal links and network nodes at different stages of the overall process. An increase in the density of the network leads to a decrease in the rate of the thermooxidative degradation of internodal chains and an increase in the rate of decay of network nodes.