Low air pressure combustion of Al/CuO/PVDF electrospun films: design guidance for energetic encapsulation of microthruster arrays

Energetic interfacial films represent a promising encapsulation material for micro- thruster arrays in near-Earth orbit, where their combustion performance under low- pressure or vacuum conditions is critical for practical application. Herein, a uniformly dispersed layered energetic composite film suitable for scalable array encapsulation has been designed via electrospinning technology. The ternary composite energetic film consists of interwoven polyvinylidene fluoride/aluminum/copper oxide (PVDF/Al/CuO) nanofibers. Morphological analysis confirms the effective loading of nanoparticles (Al and CuO) onto the fibers. Energetic films fabricated by this method significantly suppress particle agglomeration. Thermal analysis reveals atmosphere-dependent exothermic pathways. Constant-volume combustion experiments demonstrate that energy release is modulated by film thickness. The evolution of the film ablation flow field has been investigated. Crucially, transient resistance thermometry has for the first time reported the phenomenon of increasing ignition temperature of energetic materials with decreasing pressure under low-pressure conditions. At 1 kPa, the ignition temperature is significantly elevated compared to that at atmospheric pressure. Propagation velocity characterization uncovered a counterintuitive phenomenon: below 10 kPa, 610 μm-thick films exhibit a 42% lower propagation velocity than 270 μm-thick films, a phenomenon termed the thickness-compensation failure effect. An asymmetric heat transfer-dissipation theory is proposed to explain this inversion through geometric thermal management. This work provides crucial experimental evidence and a theoretical foundation for guiding the design of energetic films for vacuum-operating micro-thruster array encapsulation.