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A New Method for Predicting the Friction Sensitivity of Nitramines

Keshavarz M. H., Hayati M., Ghariban-Lavasani S., Zohari N.

Central European Journal of Energetic Materials

2015

Vol. 12, no. 2

215--227

This study presents a new simple correlation between friction sensitivity of nitramines and their molecular structures. This novel correlation can help chemists and chemical engineers to predict the friction sensitivity of new nitramines without using any experimental data, which is important for safety in industrial processes. The new correlation can also help to elucidate the mechanism of initiation of energetic materials by frictional stimuli. This new method assumes that friction sensitivity of a nitramine of general formula CaHbNcOd can be expressed as a function of the optimized elemental composition and the contributions of specific molecular structural parameters. The new correlation has root mean square and average deviations of 7.64 and 6.44 J, respectively, for 20 nitramines with different molecular structures. The proposed new method was also tested for 11 nitramines containing complex molecular structures.

Study of TATP: Mass Loss and Friction Sensitivity During Ageing

Matyáš R., Šelešovský J., Musil T.

Central European Journal of Energetic Materials

2012

Vol. 9, nr 3

251-260

Triacetone triperoxide (3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-hexoxonane; TATP) is one of the most frequently used improvised explosives, often misused worldwide. In our previous studies, we had observed that the kind of acid used to catalyse its formation has a significant influence on TATP's properties. TATP was prepared using five different acids that are often used in improvised conditions. All of the samples were subjected to natural ageing in both open and closed vials at laboratory temperature. During ageing, TATP sublimes and decomposes. The changes in crystal size and shape after ageing were documented by optical microscopy. The mass loss was monitored about every third day during ageing. Samples prepared using sulphuric and perchloric acids lose weight more quickly than the others due to chemical decomposition. The friction sensitivity was determined for all samples before and after ageing. Neither the type of acid used nor the influence of closing the vials had any significant influence on the friction sensitivity after ageing. The friction sensitivity of all tested samples of TATP was about the same ? between that of lead azide and that of mercury fulminate.

Friction Sensitivity of the ε-CL-20 Crystals Obtained in Precipitation Process

Szczygielska J., Chlebna S., Maksimowski P., Skupiński W.

Central European Journal of Energetic Materials

2011

Vol. 8, nr 2

117-130

The purpose of this work was to obtain samples of CL-20 by precipitation process in a solvent/nonsolvent system, under variable process parameters such as: antisolvent kind, time of nonsolvent addition, stirrer speed, mass of seeded crystals of ε-CL-20. Received samples were studied in the aspect of their sensitivity to friction. As the results of the crystallization processes were prepared crystals of different sizes and shapes depend on applied parameters. It was affirmed, that applied antisolvent has essential influence on type of received crystals. CL-20 crystals of cuboid shape and sizes of 80-200 μm were obtained by recrystallization from ethyl acetate/chloroform. As the result of the recrystallization from ethyl acetate/xylene crystals with rounded edges were obtained. Crystals, from both samples, were mostly single and showed the lowest sensitivity to friction. Also, the crystals of irregular shape and sharp-edged agglomerates were obtained from systems with n-heptane, isooctane, cyclohexane and toluene, which revealed the highest friction sensitivities.