Viscous Reaction Growth Mechanism for High-energy Propellant Containing Energetic Binders Under Shock Wave Loading

The shock initiation of high explosives has been widely studied under shock-wave loading. However, the reaction growth of propellants containing high-energy oxidants and energetic binders has not been explored. Such exploration is crucial for extending the use of propellants under extremely unexpected stimuli. A one-dimensional Lagrangian testing system based on an embedded pressure gauge was established to capture the reaction growth history of glycidyl azide polymer/cyclotrimethylene trinitramine/triethylene glycol dinitrate propellant (GRT propellant). We found that the initiation threshold and reaction growth depend on the initial microstructure and composition. Compared to high explosives, GRT propellants' higher initiation threshold (4.4–14.5 GPa) is attributed to energy absorption by the binder matrix and fewer initial micro defects. Before the binder's potential chemical energy is liberated, the additional energy absorption of the binder causes part of the energy consumed near the wavefront, forming an arched pressure wave. This energy is usually used to form the chasing compression wave that supports the detonation formation. An effective chasing compression wave can be formed when high enough frontier pressure (>9.0 GPa), thereby leading to a viscous reaction growth on the wavefront. Also, the relatively low mechanical sensitivity of ammonium perchlorate increases the initiation threshold, delaying the detonation establishment (the run to detonation: 15–20 mm). Although the addition of cyclotrimethylene trinitramine crystal allows GRT propellant to detonate, the relatively slow explosive decomposition of other components makes it have a wide chemical reaction zone of 240 ns.