Fluorinated Polyphosphazenes for Insensitive Pyrotechnics

Fluorinated Polyphosphazenes for Insensitive Pyrotechnics

Author: ChemistryViews.org

Energetic polyphosphazenes constitute a class of high energy low sensitivity materials that are extremely versatile and which are currently considered as fillers for all kinds of munitions to make them insensitive. Insensitive Munitions (IM) typically react less fierce when accidentally exposed to fire, bullet impact or shaped charge jet impact. That is they do not detonate upon the above stimuli, but deflagrate or merely burn as is described in the NATO publication STANAG 4439.

Ernst-Christian Koch and Alessandro E. Contini, Centre for Defence Chemistry, Shrivenham, UK, have identified the non-energetic poly[bis(2,2,2-trifluoroethoxy)phosphazene] (PTFEP) (–N=P(OCH2CF3)2–), as an alternative oxidizer to both polytetrafluoroethylene (PTFE) (aka: Teflon®) and hexafluoropropene-vinylidene fluoride-copolymer (aka: Viton® A) in magnesium based pyrotechnics (MTV flares). These MTV pyrotechnics typically are used in vital infrared countermeasure flares for self-protecion of aerial platforms against infrared guided missiles and are used as high performance igniters for low vulnerability (LOVA) propellants.

Both theoretical calculations and experimental works showed that PTFEP is an ideal replacement of both Teflon® and Viton® A in MTV as it combines both the oxidational power and the binding efficiency. Moreover, PTFEP is a superior oxidizer in that it enhances the combustion plume over standard fluorocarbons through liberation of hydrogen and nitrogen gas. Preliminary testing indicates lower mechanical and thermal sensitivity of corresponding formulations compared to standard MTV payloads making these materials prospective insensitive flare and igniter materials for insensitive pyrotechnics to protect and serve tomorrow’s warfighters.

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