Effect of propellant components on degradation of polyether-urethane binder (1). Effect of nitrate esters

The effect of two nitrate esters (NG, BTTN) on the degradation of EO/THF copolyether/urethane binder was studied by structural analysis of degradation products with FT-IR and NMR methods. Alcohols are the main degradation products of these two nitrate esters. Structural confirmation proves that these alcohols are mainly generated from the hydrolysis of nitrate esters and subsequently undergo the repolymerization with isocyanates to form carbamates. It was also surprisingly found that nitrate esters show some stabilizing effect on the polyurethane binder but result in high proportion of formates and tertiary carbons in the degradation products of polyurethane and that no efficient absorption of nitric free radicals by centralite II was found on the current experimental conditions. To explain these observations, a mechanism was suggested that the nitric free radicals derived from the decomposition of nitric esters react with peroxides to form nitric acid, which accelerate the hydrolysis of nitrate esters.