Tailoring Structural Energetics for Enhanced Reactivity of Nano-Aluminum Particles Based Microspheres

Porous nano-aluminum@polymer microspheres with a narrow size range are fabricated to exploit the energy advantages of nano-aluminum (nAl). Nitrocellulose (NC) and glycidyl azide polymer (GAP) act as functional binders and adhere tightly to the surface of nAl particles and aggregate them into spheres. The formed holes on the microsphere surface are considered gas diffusion channels to the microsphere interior. Confined combustion results show that nAl@GAP microspheres generate the highest peak pressure, and maximum pressurization rate of nAl@NC microspheres is comparatively higher than that of others. Given the microsphere structure, thermal behavior in air shows that the oxidation-reaction mechanism of the microspheres is close to that of nAl particles. Interfacial reactions between nAl particles and gases produced by polymer decomposition enhance microsphere reactivity. The heat released by polymer decomposition maintains the structure, activates nAl particles, and accelerates combustion propagation, which are positively correlated with the energy content of the polymer. The unconfined test results showed that nAl@GAP microsphere combustion propagates faster than that of nAl@NC microspheres.