A Promising Fuel for Variable Thrust Motor: HTPB Propellant with High Pressure Exponent

In this paper, we developed a HTPB propellant containing energetic compound hydrated-tetra-(-amino-1,2,4-triazole) copper perchlorate (ACP) as the fuel for variable thrust motor with the purpose of controlling gas flow. Formulation of the propellant was designed and then various performances of this propellant were investigated. Results show that HTPB propellant containing 2 % ACP has a pressure exponent of 0.57 (static) or 0.56 (dynamic), suggesting an excellent capacity to control the burning rate. Thermal decomposition of ACP and the decomposition of ammonium perchlorate (AP) in high temperature are demonstrated to be sensitive to pressure by PDSC analysis, moreover, decomposition of AP in high temperature (around 400 degrees C) could be accelerated by ACP, phi 50 mm motors charged with this propellant work stably in the pressure range from 1.18 MPa to 21.72 MPa and less aluminum (Al) deposits in chambers and nozzles. Mechanical performance of the propellant in -40 degrees C and 20 degrees C turns out to be excellent with sigma(m)>= 0.96 MPa and epsilon(b)>= 20.92 %, and is better than that in 50 degrees C. Low impact sensitivity (H-50, 72 cm) and friction sensitivity (P, 31 %) of HTPB propellant containing 2 % ACP are found in the security tests, the propellant is also insensitive to shock wave (G(50), 23.8 mm).