Spark sensitivity and light signature mitigation of an Al/SnO2 nanothermite by the controlled addition of a conductive polymer

Abstract

The development of insensitive energetic composite materials is a research topic of growing interest. Nanothermites, which are described as a highly reactive mixture of metal and metal oxide, are the focus of this challenge.In this work, the conductive polymer polyaniline (PAni) was introduced into an Al/SnO2 energetic nanocomposite either via the preparation of a SnO2-PAni composite or as a powdered ternary compound. Both PAni-enriched Al/SnO2 nanothermites were characterized in terms of sensitivity (impact, friction, electrostatic discharge (ESD)) and reactive properties (combustion velocity). The two methods were compared to evaluate which one achieved the best compromise for the nanothermite in terms of performance (sensitivity/combustion properties). When the polymer is intimately structured with the oxide, it is possible to reduce the sensitivity of the energetic composition as a function of the additive amount. The polymer easily conducts the electrostatic charges through the energetic matter until the nanothermite presents no handling danger: ESD varied from 0.42 to 246.1 mJ for the safer composition (4.80 wt% of PAni). On the other hand, when PAni powder was added to the nanothermite, the ESD threshold did not vary because no continuous conductive phase was created within the material. Concerning the reactive properties of the Al/SnO2 energetic system, with the addition of PAni (2.04 wt%) as an SnO2-PAni hybrid matrix, the combustion velocity decreased from 800 to 500 m/s combined with a lower luminous signature.The use of a structured conductive polymer as a desensitizer within nanothermites, represents a significant step forward in the development of safer and reactive energetic compositions.