Vacuum stability evaluation of pyrotechnic mixture - double-base propellant compatibility

Abstract. This study investigates the compatibility between a binder-free pyrotechnic mixture and a double-base rocket propellant containing a high nitroglycerin content. Under realistic application and service conditions, these components are separated by a very thin aluminum foil coated with a polymer layer, which serves as a physical barrier preventing direct interaction. The research specifically examines the significance of the presence and integrity of this physical barrier in mitigating hazardous interactions between the two energetic components. Prior to compatibility testing, comprehensive laboratory analyses were performed to assess the chemical stability of each individual component. Subsequently, compatibility was evaluated using the vacuum stability test in accordance with STANAG 4147, selected for its suitability in studying energetic material interactions and for the flexibility it offers in modifying test parameters. Two test regimes were applied: a 40 h test at 100 °C and an extended 240 h test at 80 °C. In the 100 °C test, the pyrotechnic mixture was treated as the energetic material and the propellant as the contact material, while the roles were reversed in the 80 °C test. The results reveal pronounced incompatibility between the two energetic components in the absence of an effective barrier. The findings clearly demonstrate that a solid, continuous, and durable physical barrier is essential to prevent premature or hazardous interactions. Any damage or degradation of this barrier prior to the intended ignition may lead to uncontrolled interaction initiated by combustion of the pyrotechnic mixture. Differential thermal analysis of the individual components and their mixture showed undesirable shifts of the recorded thermal peaks toward higher temperatures, indicating potential interactions between the components that may affect the thermal behavior and compatibility of the system.