Synthesis and Characterization of Novel Stabilizers for Nitrocellulose-Based Propellants

Propellants containing nitrocellulose (NC) continuously decompose. The decomposition products released in the process increase the rate of the decomposition and a self-accelerating behavior is obtained. To prevent the autocatalysis, stabilizers are added to NC/NG-based propellants. The action of the stabilizers is to trap the nitrous decomposition products and form stable compounds, which prevent or delay further decomposition. The most common stabilizers are aniline derivatives, which can form potentially toxic and/or carcinogenic nitrosamine derivatives during prolonged storage in propellants. This work is the joint effort between the Swedish Defence Research Agency (FOI) and Eurenco Bofors (EuB) to find new stabilizers without any amine moiety to avoid nitrosamine formation, which has resulted in a new class of stabilizers with plasticizing properties. The paper describes the concept of this class of plasticizing stabilizers, the synthesis of these compounds and characterization of their performance as stabilizers. The most promising stabilizer was found to be bis(2,6-dimethoxyphenyl)triethyleneglycol (Stab-5). Kilogram scale production of this substance at FOI allowed evaluation of its stabilizing effect in real propellants and its effect on the burning rate in a double-base rocket motor at EuB. Accelerated ageing of a double-base propellant stabilized with Stab-5 was applied in order to identify the compounds that were obtained in the reaction between the stabilizer and the decomposition products.