To support expected lifetime determination efforts of polymer bonded explosives, understanding degradation mechanisms governing aging behavior of eutectic bis-2,2-dinitropropyl acetal and bis-2,2-dinitropropyl formal [called nitroplasticizer (NP) herein] under various environmental conditions is crucial. To this end, NP degradation has been studied extensively and this study continues a long running effort among the DOE complex and greater energetic materials community. Much of this past work contributes to a foundational hypothesis wherein NP degradation initiation primarily starts through HONO elimination (including HONO formation-decomposition, i.e., NP → NP’ + NO + NO2 + H2O). Depending on aging conditions, generation of NOx and H2O results in a series of cascading reactions further degrading NP and NP’. However, many of the byproducts from this proposed mechanism lack direct condensed phase identification by high-resolution mass spectrometry, particularly so from a variety of environmental conditions at moderate temperatures. Therefore, 240 samples of NP were prepared under three environments, at four temperatures, and aged over 44 months. The aged samples were analyzed using a suite of thermal, chemical, and spectroscopic methods. Here, the results from liquid chromatography tandem quadrupole time of flight mass spectrometry (LC-QTOF) will be discussed. The findings of this work continue to support HONO elimination as the primary step in the initiation of NP degradation at moderate temperatures.

Identification of nitroplasticizer degradation products: HONO elimination mechanism verification by liquid chromatography tandem quadrupole time of flight mass spectrometry

ACS Fall 2021

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