Energy evolution mechanism of a PVDF activated nano-aluminum based metastable intermixed composites

Abstract

The preparation and energy release mechanism of highly reactive n-Al/F-polymer metastable intermixed composites are both desirable and challenging. In this study, we employed an optimized electrospray sampling strategy to significantly enhance the reaction activity of aluminum-based MICs, as well as their combustion performance. It is evident that the optimization of the sampling strategy yielded remarkable results. Compared to the physical mixture, MICs-1 exhibited a 7.2-fold and 9.9-fold increase in Pmax and Pmax/Δt, respectively. The combustion rate experienced an 8.5-fold improvement, and the energy release efficiency rose from 52.18 % to 68.11 %. An analysis of the energy evolution mechanism reveals a mitigation of the reactive sintering phenomenon observed in MICs-1. The presence of PVDF facilitates the reactivity of aluminum powders by selectively corroding the alumina shell. The reaction kinetics parameters indicate that MICs-1 demonstrates characteristic three-step reaction behavior and exhibits a lower reaction energy barrier. Furthermore, ReaxFF molecular dynamics simulations demonstrate the adsorption and dissociation of PVDF on the surface of aluminum powders, leading to erosion defects in the alumina crystal structure. These defects, in turn, induce the ignition reaction.