Composite propellant based on a new nitrate ester

Abstract

Composite propellants based on the solid nitrate ester 2,3-hydroxymethyl-2,3-dinitro-1,4-butanediol tetranitrate (SMX) were theoretically and experimentally examined and compared to formulations based on ammonium perchlorate (AP). Thermochemical equilibrium calculations show that aluminized SMX-based formulations can achieve theoretical sea level specific impulse values upwards of 260 s. Both ignition sensitivity (tested via drop weight impact, electrostatic discharge, and BAM friction) and physical properties (hardness and thermal properties) are comparable to those of the AP-based formulations. However, the SMX-based formulation could be detonated using a high explosive donor charge in contact with the propellant. Differential scanning calorimetry of the SMX-based propellant indicated an exotherm onset of 140°C, which corresponds to the known decomposition temperature of SMX. The propellant has a high burning rate of 1.57 cms-1 at 6.89 MPa, with a pressure exponent of 0.85. This high pressure sensitivity might be addressed using various energetic and/or stabilizing additives. With good performance and high density, SMX-based composite propellants may offer a promising perchlorate-free alternative to existing AP-based formulations.