No abstract

The aim of this work was to desensitize keto‐RDX, respectively 2‐oxo‐1,3,5‐trinitro‐1,3,5‐triazacyclohexane (K6). For this purpose, two different methods were employed. First, nano‐K6 was produced by means of the Spray Flash Evaporation process. Particles with a median size of 74 nm were obtained. Sensitivity to friction and electrostatic discharge were reduced by downscaling particle size of K6. Second, due to their molecular analogy, the mixing of K6 and RDX was studied. For that reason, a physical nanometric mixture of K6 and RDX was produced by the same technique. In the latter case, an inter‐particular synergy between both compounds was noticed but without forming a cocrystal. The median particle size of the mixture is about 82 nm, and its sensitivity is between the ones of raw nano‐materials concerning friction and electrostatic discharge. Moreover, the mixture is less sensitive to impact (3.03 J) than nano‐K6 (<1.56 J) and nano‐RDX (threshold is 2.0 J).

During the degradation of the propellant stabilizer Centralite I the 2‐nitro‐N‐nitroso‐N‐ethylaniline 2N‐NO‐EA is formed showing two signals in the chromatographic analysis (HPLC) with a 2 : 1 ratio, while the 4‐nitro isomer presents only one signal. This completely unexpected behaviour which interferes with the qualitative and quantitative determination was supposed to be due to the presence of two isomeric forms; however, the existence of two rotameric forms cannot be excluded. A detailed parameter study of the analytical conditions showed that at temperatures of 5 °C the isolation of the two forms should be possible. Preparative chromatography on a RP‐18 column at 5 °C indeed gave fractions with differing percentages of both forms; at room temperature a re‐equilibration to the starting ratio of 2 : 1 was observed.

This study deals with the crystallization behaviour of several dinitramines with plasticizing abilities in a nitrocellulose‐based gel. The tendency of these compounds to interact with nitrocellulose is an important parameter for the development of new propellants, especially for those which should have a temperature‐independent combustion. It is shown that, on the basis of their crystallization behaviour, the nine studied dinitramines form three different groups. Whereas the first one (large symmetrical molecules) exhibits a strong crystallization tendency, the second group (asymmetric compounds) has low crystalline contents and shows a good interaction capacity with nitrocellulose. At last, DNDA6 (2,4‐dinitro‐2,4‐diazahexane) with 3.3 noncrystallizing molecules per anhydroglucosidic unit of nitrocellulose, presents the most pronounced interaction with nitrocellulose, due to its lowest content of crystalline plasticizer.

This work contributes to the growing interest in predictions linked with energetic salts. A reliable method to accurately compute the heat of formation of triazole-based salts was investigated. Calculations were based on Born-Haber energy cycles: gas-phase enthalpy of ions and lattice enthalpy were calculated separately. Ten triazole-based salts were synthesized and fully characterized. Their heat of combustion was measured by bomb calorimeter. Gas-phase heat of formation of cations and anions were computed at four different levels of theory: B3LYP 6-31G(d,p), CBS-4M, CBS-QB3, and G4. Ionic volumes were calculated at the B3LYP 6-31G(d,p) level with and without corrections. Lattice enthalpy estimations, based on calculated ionic volumes, were performed with the help of Jenkins and Gutowski methods. Combinations of the obtained results (gas-phase enthalpy of ions and lattice enthalpy) were used in the Born-Haber approach to predict solid phase enthalpy of formation of studied energetic salts. Direct comparison with experimental measurements enabled the identification of the most reliable path for energetic salt standard enthalpy of formation prediction.