The propellant charge first suggested for the Archer system was a bimodular charge system with two different propellants. This is a common solution that has several disadvantages in relation to a unimodular charge where all the modules are equal. To design a fully functioning unimodular system is however rather difficult; and numerous efforts has been made (by several manufacturers) to design such a system.
The use of new energetic fillers developed at FOI; makes it possible to tweak the burning characteristics in such a way that the design problem of a unimodular charge might be solved. A recent government funded project has addressed the possibility to develop a low sensitity unimodular charge system where several propellant components have been up-dated.
After a screening of possible filler and binder systems; a system based on nitrocellulose (NC); guanylurea dinitramid (FOX-12) and energetic plasticizers was selected. The reason to select NC was price and performance whereas FOX-12 and NENA were selected due to the low sensivity and good burning behaviours. Acardite II was the first choice of stabilizer and is considered among the best stabiliser for NC/energetic plasticizer systems. Acardite II is however; as many other well known stabilizers; known to form nitrosoamines when it reacts with the nitrous oxides formed in the decomposition of the propellant matrix. As nitrosoamines are infamous for their carcinogenity a new group of compounds was investigated; not previously used as stabilizers for NC; namely phenyl aliphatic ethers.
In this work; the preferred phenyl aliphatic ether was 1;4-dimethoxybensene. With this compound as a stabilizer; the propellant fulfils the storage stability test (STANAG4582) at 90 ¬įC; corresponding to 20 years of storage at 25¬į C. The new compound is considered as a replacement stabilizer for diphenylamine derivatives used in NC-containing propellants. The conclusion is that these new stabilizers have similar or better effect in stabilizing NC-based propellants than diphenylamine-derivatives and that they do not form carcinogenic nitrosamines.
* Uniflex 2 and Archer are both trademarks belonging to BAE-systems Bofors AB.