Preparation and combustion of laminated iodine containing aluminum/polyvinylidene fluoride composites

Abstract

Energetic materials with a high iodine content and tunable reactivity are desirable for application as a biocidal agent. In this paper, aluminum/polyvinylidene fluoride (Al/PVDF) composites with different iodine content were prepared by an electrospray deposition method. Most of the iodine in the films are found to be fixed by PVDF and aluminum, which is released at 250 °C and 450 °C respectively. The heat release and burning rate of the iodine-containing films decreases with the increase of iodine content. With an iodine content of ≥40 wt.%, the film did not propagate. However, when fabricated in a laminate structure the threshold for iodine loading to sustain propagation increased to 67 wt.%. Evaluation of several multi-layered structured films indicated that an optimum single layer thickness of ∼25 µm produced the fastest reaction velocity, with loadings of up to 67 wt.% iodine. The thermal decomposition and oxidation of the laminated Al/PVDF films are also investigated. It appears thus that iodine which acts as a reaction retardant can be loaded in higher concentrations if it is physically separated from the primary energetic. In so doing, the primary energetic can maintain a continuous ignition threshold to propagate and enable the heat released from reaction to evolve gas phase iodine.