Hydroxyl‐terminated Polybutadiene Curing by 1,3‐dipolar Cycloaddition of Energetic Nitrile N‐Oxides: Room Temperature Curing Property, Kinetics, Thermodynamics, and Propellant Combustion Characteristics

Abstract

Abstract5‐nitro‐1,3‐benzenedichloroaldehyde oxime was designed and synthesized to achieve room temperature curing of HTPB binders, and its structures were characterized. A new kind of 1,3‐dipolar cycloaddition reaction system was formed by HTPB as main resin, 5‐nitro‐1,3‐benzenedichloroaldehyde oxime and triethylamine as curing agent. The results revealed that the formation of isoxazoline ring in cured HTPB elastomers mainly derived form the reaction of Nitrile N‐Oxide with cis alkene of HTPB, and the cured HTPB elastomers underwent three stages decomposition. The kinetic parameters and thermodynamic parameters for the 14 % curing agent's sample were obtained from the DSC data. The activation energy was computed to be 204.75 kJ mol−1 and pre‐exponential factor was 1.38×1023 s−1.The burning rate of the propellant showed that the propellant with HTPB cured by containing −NO2 Nitrile N‐Oxides (100 % HTPB, 14 % Nitrile N‐Oxides, 2 % Aluminum and 77 % Ammonium perchlorate, Curing at 25 °C for 5 days ) had a higher burning rate and pressure exponent compared to conventional HTPB propellant (100 % HTPB, 14 % toluene diisocyanate, Nitrile N‐Oxides, 2 % Aluminum and 77 % Ammonium perchlorate, Curing at 60 °C for 5 days). Therefore, the containing −NO2 Nitrile N‐Oxides curing system could be used as a novel promising curing system for HTPB‐based solid composite propellants.