Assessing chemical inter-reactivity of high explosives. An outline for an adequate way

Abstract. Assessing chemical stability and compatibility of energetic materials is already a long lasting task. At present, mostly traditional materials have been tested and evaluated. For them the established methods work mostly well, this also because of the already long and extensive experience with them. Newer materials as FOX-12, ADN, new organic oxidizers based on the nitro formate group, new energetics based on nitrogen-rich molecular groups as triazol and tetrazol are entering into the development and formulation departments and may reach or in part have reached demonstrator level and even in-service level. In part, some newer materials show good chemical stability, another part has to be evaluated with care. Both groups have in common that the experience with introduced and known material is not transferable directly. A more adapted assessment is necessary. Often the assessment is based only on methods like DSC and TGA, which provide results with small amounts of material in a short time, which is addressed as great advantage. With some evaluation software programs and some measurements a thorough evaluation and comparison is propagated. However, such fast determinations are by far not sufficient to get a correct information about thermo-chemical stability and compatibility. This paper will clarify how assessments of thermo-chemical decomposition should be performed in order to obtain reasonable results. The often overseen effect of the temperature weighting caused by activation energy will be demonstrated and the consequences by this effect discussed. Next is the necessity to make the experimental determinations in such a way to reach enough conversion of the decomposition reaction. It is shown that the typical DSC measurements are not suitable to be used for sentencing the decomposition for lower temperature ranges at in-service conditions. The next question is the about the limit values allowable with methods as gas generation, heat generation and mass loss. Until now, this question is not satisfactorily answered, especially with heat generation and gas generation, which are determined by heat flow microcalorimetry and vacuum stability test apparatus, respectively. A way to come to conclusive values will be outlined and discussed.