Thermal decomposition studies on copolyurethanes based on hydroxyl terminated polybutadiene and poly(12-hydroxy stearic acid-co-TMP) ester polyol

Thermal degradation of copolyurethanes based on hydroxyl terminated polybutadiene (HTPB) and poly(12-hydroxy stearic acid-co-TMP) ester polyol (PEP) with varying compositions has been studied by thermo-gravimetric and pyrolysis–GC techniques. The copolyurethanes were found to decompose in multiple stages and the kinetic parameters were found to be dependent on the method of their evaluation. The activation energy for the initial stage of decomposition was found to increase, and for the main stage decreases with the increase in PEP content. The pyrolysis–GC studies on the ammonium perchlorate filled copolyurethanes (solid propellants) showed that the major products during the pyrolysis were C2, C3 hydrocarbons and butadiene. The amount of C2 fraction in the pyrolyslate increased with solid loading, as well as with the HTPB content in the copolyurethanes. A linear relationship apparently exists between the amount of C2 fraction and the burn rates of the solid propellants.