Bulletin of the American Physical Society
19th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 60, Number 8
Sunday–Friday, June 14–19, 2015; Tampa, Florida
Session H2: Energetic and Reactive Materials IV: Novel Materials |
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Chair: Timothy Weihs, Johns Hopkins University, Rebecca Wilson, Naval Surface Warfare Center, Indian Head Room: Grand F |
Tuesday, June 16, 2015 9:15AM - 9:30AM |
H2.00001: Searching for new energetic materials: Computational design of novel nitro-substituted heterocyclic explosives Roman Tsyshesvky, Philip Pagoria, Maija Kuklja The continuous search for safe and powerful energetic materials is an exciting research challenge that attracts experts in material science, chemistry, physics, and engineering. Elucidation of meaningful correlations between sensitivity and structures of explosives is a fundamental problem, which ought to be resolved to ensure successful design of new materials and improvements of existing energetics. In this report, quantum-chemical DFT study of thermal decomposition of a series of recently synthesized oxadiazole-based explosives, BNFF (3,4-bis(4-Nitro-1,2,5-oxadiazol-3-yl)-1,2,5-oxadiazole-N-oxide), BNFF-1 (3,4-bis(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,5-oxadiazole) and ANFF-1 (3-(4-amino-1,2,5-oxadiazol-3-yl)-4-(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,5-oxadiazole) is presented. We also show how the knowledge of discovered correlations between structures and thermal stability of these compounds is used to design several novel candidate heterocyclic energetic molecules, including DNBTT (2,7-dinitro-4H,9H-bis([1,2,4]triazolo)[1,5-b:1',5'-e][1,2,4,5]tetrazine), compound with high thermal stability, which is on par or better than that of TATB. [Preview Abstract] |
Tuesday, June 16, 2015 9:30AM - 9:45AM |
H2.00002: Cesium Pentazolate: a New Nitrogen Rich Energetic Material Brad Steele, Elissaios Stavrou, Harry Radousky, Joseph Zaug, Jonathan Crowhurst, Ivan Oleynik Nitrogen, which forms strong triple bonds in molecular diatomic nitrogen N$_{\mathrm{2}}$ at low pressures, was predicted to transform to single-bonded cubic-gauche crystal upon compression above 50 GPa. However, experimental realization of polymeric forms of nitrogen proved to be difficult. Here we report theoretical and experimental evidence for a new class of high-nitrogen content compounds consisting of molecular pentazoles, which are stabilized in the crystal phase upon introduction of elemental cesium. First-principles structural predictions show that the material with composition CsN$_{\mathrm{5}}$ is thermodynamically stable above 30 GPa. Indexing of the measured X-ray diffraction spectra indicate the synthesis of this material at 60 GPa as well its stability upon decompression down to 24 GPa. Their energetic capacity and stability make these alkali-metal pentazolates excellent candidates for high-energy density materials. [Preview Abstract] |
Tuesday, June 16, 2015 9:45AM - 10:15AM |
H2.00003: Synthesis, Chemical and Physical Characterization of TKX-50 Invited Speaker: Thomas Klapoetke TKX-50 (bis(hydroxylammonium) 5,5'-bis(tetrazolate-1$N$-oxide)) is one of the most promising ionic salts as a possible replacement for RDX. The thermal behavior of TKX-50 (bis(hydroxylammonium) 5,5'-(tetrazolate-1$N$-oxide)) and the kinetics of its thermal decomposition were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The calculated results of the detonation parameters and equations of state for the detonation products (EOS DP) of explosive materials TKX-50 and MAD-X1 and several of their derivatives were obtained using the computer program EXPLO5 V.6.01. These values were also calculated for standard explosive materials which are commonly used such as TNT, PETN, RDX, HMX as well as for the more powerful explosive material CL-20 to allow comparisons to be made. The determination of the detonation parameters and EOS DP was conducted both for explosive materials having the maximum crystalline density and for porous right up to 50{\%} in volume materials. The influence of the content of plastic binder polyisobutylene used (up to 20{\%} in volume) on all of the investigated properties was also examined. Calculated results on shock wave loading of different inert barriers in a wide range of their dynamic properties under explosion on their surfaces of concrete size charges of different explosive materials in various initial states were obtained with the use of the one-dimensional computer hydrocode EP. Barriers due to materials such as polystyrene, textolite, magnesium, aluminum, zinc, copper, tantalum or tungsten were examined (Fig. 1). Initial values of pressure and other parameters of loading on the interface explosive-barrier were determined in the process of conducted calculations. Phenomena of propagation and attenuation of shock waves in barrier materials were considered too for all possible situations. From these calculations, an essentially complete overview of the explosion properties and characteristics of shock wave action onto barriers was obtained for several new and also for several standard explosive materials as a comparison. [Preview Abstract] |
Tuesday, June 16, 2015 10:15AM - 10:30AM |
H2.00004: Photoactive energetic materials: linear and nonlinear photochemistry of chromophore linked energetic materials Margo Greenfield, Shawn McGrane, Cindy Bolme, David Chavez, Jacqueline Veauthier, Susan Hanson, Thomas Myers, Jason Scharff In general, conventional molecular explosives are white to off-white in color and only absorb ultraviolet light. A novel approach to synthetically link optically active energetic chromophores to existing molecular energetic materials has resulted in increased photoactivity in the visible (532 nm) region of the electromagnetic spectrum. Tetrazine, an energetic optically active chromophore, which absorbs around 532 nm, has been derivatized with various energetic materials including pentaeythritol tetranitrate (PETN), nitroglycerine (NG) and dinitroazetidine (DNAZ). We report the corresponding photochemistry and photochemical quantum yields of these new materials under various wavelength and intensity regimes. [Preview Abstract] |
Tuesday, June 16, 2015 10:30AM - 10:45AM |
H2.00005: Energetic Co-Crystal of Trinitrophloroglucinol-Melamine Patrick Bowden, Phil Leonard, Kyle Ramos, Hongzhao Tian We hope to harness the field of energetic co-crystals for development of insensitive, high-performing explosives. As demonstrated by other groups, co-crystals of energetic materials are diverse in their resultant properties versus the native materials. Herein, we discuss the synthesis, characterization, scale-up and testing of energetic co-crystals of trinitrophloroglucinol (a.k.a 1,3,5-trihydroxy-2,4,6-trinitrobenzene) and melamine. Although melamine is not an energetic material, high nitrogen content and insensitivity can be of benefit in a co-crystal. Currently, trinitrophloroglucinol (TNPG) and melamine have been found to exist as a co-crystal in a 2:1 and 1:1 ratio. Characterization by NMR, IR, LC-MS, sensitivity, thermal stability, calorimetry and powder X-ray diffraction have all been used to characterize the individual compounds as well as the co-crystals developed. Performance testing of pressed co-crystals has been achieved on 1'' (25.4 cm) diameter rate sticks. [Preview Abstract] |
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