Azide-bearing polymer-based solid composite propellant prepared by a dual curing system consisting of a urethane-forming reaction and a dipolar addition reaction

• Azide-bearing polymer-based solid propellants were prepared by using the urethane, the triazole, or dual curing systems.
• The dual curing system offered the best mechanical properties as well as high burn rate and low pressure exponent.
• The dual curing system also produced excellent adhesion between the GAP-based solid propellant and the HTPB liner.

Solid composite propellants based on a polymer bearing azide pendent groups, glycidyl azide polymer (GAP), were prepared by urethane- or triazole-forming reactions and their combination. Dipolarophiles featuring diacetylenic groups, such as bispropargyl succinate (BPS) and 1,4-bis(1-hydroxypropargyl)benzene (BHPB), were used as the curatives in the triazole curing system. Among the three types of curing systems used for the preparation of GAP-based solid composite propellants, dual curing systems provided the best mechanical properties, regardless of the oxidizer type included in the solid composite propellant. The dual curing system produced GAP-based solid composite propellants that exhibited a higher burn rate and a lower pressure exponent compared to propellants obtained from a single triazole curing system. Finally, good adhesion to the hydroxyl-terminated polybutadiene (HTPB)-based liner was observed in the GAP-based solid propellants prepared from the dual curing system.