Bulletin of the American Physical Society
20th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 62, Number 9
Sunday–Friday, July 9–14, 2017; St. Louis, Missouri
Session C2: Energetic and Reactive Materials: Synthesis and New Molecules I |
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Chair: Jesse Sabatini, Army Research Laboratory Room: Grand Ballroom AB |
Monday, July 10, 2017 11:15AM - 11:45AM |
C2.00001: Manipulating explosive sensitivity through structural modifications in a nitrate ester system Invited Speaker: Virginia Manner Understanding how condensed phase effects influence sensitivity is essential for developing next generation insensitive high explosives. However, the ability to predictably manipulate explosive sensitivity remains an elusive goal. Explosive sensitivity has been suggested to be governed by multiple factors, from intramolecular effects such as bond dissociation energy, oxygen balance, and the electrostatic potential of reactive functional groups, to larger scale effects, such as crystal structure and hot spot formation. We have developed derivatives of the explosive pentaerythritol tetranitrate (PETN) and examined them experimentally and theoretically, in order to better understand which properties influence sensitivity. With this molecular framework, we can evaluate how small changes to the structure of the molecule influence qualities such as oxygen balance, heat of formation, heat capacity, compressibility, crystal packing, and hydrogen bonding, through techniques such as differential scanning calorimetry, x-ray crystallography, and atomistic simulation. We have also used small-scale sensitivity testing as an initial tool to screen for large and consistent differences in handling sensitivity. We will discuss the many factors that contribute to sensitivity in this series of systematically-modified molecules as well as in existing well-studied explosive systems, such as triaminotrinitrobenzene (TATB) and nitroglycerin (NG).\\ \\In collaboration with: Thomas Myers, Marc Cawkwell, Edward Kober, Bryce Tappan, Geoffrey Brown, Mary Sandstrom, LOS ALAMOS NATL LAB. [Preview Abstract] |
Monday, July 10, 2017 11:45AM - 12:00PM |
C2.00002: Small-scale Detonation Velocity Measurement of Select CL-20 Cocrystals Vasant Vuppuluri, I. Emre Gunduz, Steven F. Son The challenge of developing novel energetic materials makes cocrystallization using existing energetic molecules useful. Cocrystallization of CL-20 with other high explosives such as HMX has been demonstrated previously to yield novel energetic materials and may have favorable detonation performance. However, detonation performance characterization of these cocrystals is challenging due to limited availability of material. Also, the contribution of bonding energy between coformers contained within the cocrystal is not well-understood. We present the comparison of steady detonation velocities of CL-20 cocrystals to their corresponding physical mixtures using microwave interferometry. With less than 1.5 g of the cocrystal material contained within 6.52 mm diameter charges, shot-to-shot variation in detonation velocity of only about 100 m/s are achievable with this technique. This variation is adequate to resolve relatively small differences between physical mixed explosive molecules and cocrystals. [Preview Abstract] |
Monday, July 10, 2017 12:00PM - 12:15PM |
C2.00003: Properties of the pressure-induced extended-solid carbon monoxide under different synthesis and processing conditions Nhan Dang, Jennifer Ciezak-Jenkins The discovery of the high-energy-density pressure-induced extended-solid/polymeric carbon monoxide (poly-CO) has opened a new paradigm of energetic materials. Considerable studies have been made to understand properties of poly-CO. However factors which control the morphology and meta-stability of recovered samples at ambient conditions have not been identified. In this presentation, we report the variations of morphology and meta-stability of poly-CO synthesized under different conditions in the GPa range. It has been found that the morphology and meta-stability of poly-CO depend on sample volume, rate of polymeric phase transition and additives. Poly-CO synthesized with a faster compression rate appears to be more structurally disordered and have higher rates of decomposition. Samples synthesized in a larger volume require either a longer time at elevated pressure or a higher pressure for the polymeric phase transitions to occur. Also, results of kinetic studies of photochemical reaction of CO at 4.5 GPa in presence of traces of H$_{\mathrm{2}}$O, HCl (1M), and concentrated H$_{\mathrm{2}}$SO$_{\mathrm{4}}$ will be presented and influences of these additives on the morphology and meta-stability of polymeric CO will be discussed. [Preview Abstract] |
Monday, July 10, 2017 12:15PM - 12:30PM |
C2.00004: Heterocyclic energetic materials: Synthesis, characterization and computational design Roman Tsyshevsky, Philip Pagoria, Aleksander Smirnov, Maija Kuklja Achievement of the tailored properties (high performance, low sensitivity, etc.) in targeted new energetic materials (EM) remains a great challenge. Recently, attention of researchers has shifted from conventional nitroester-, nitramine-, and nitroaromatic-based explosives to new heterocyclic EM with oxygen- and nitrogen- rich molecular structures. They have increased densities and formation enthalpies complemented by attractive performance and high stability to external stimuli. We will demonstrate that oxadiazol-containing heterocycles offer a convenient playground to probe specific chemical functional groups as building blocks for design of EM. We discuss a joint experimental and computational approach for design, characterization, synthesis, and modeling of novel heterocyclic EM. Combinatorically, we comprehensively analyzed how overall stability and performance of each material in the family (BNFF, LLM-172, LLM-175, LLM-191, LLM-192, LLM-200) depends upon their chemical composition and details of the molecular structure (such as a substitution of a nitro group by an amino group and 1,2,5-oxadiazole fragment by 1,2,3- or 1,2,4-oxadiazol ring). We will also discuss proposed new EM with predicted superior chemical and physical properties. -/abstract- P. Pagoria, R. Tsyshevsky, A. Smirnov, [Preview Abstract] |
Monday, July 10, 2017 12:30PM - 12:45PM |
C2.00005: Synthesis, Formulation and Evaluation of New Less Sensitive Explosives Bryce Tappan, Patrick Bowden, Robert Lebrun, Marvin Shorty, Philip Leonard, Joseph Lichthardt, Matthew Schmitt, Virginia Manner, Larry Hill The search for insensitive high-explosive (IHE) materials has been on-going for numerous decades at LANL, with numerous advances made in synthesis of new molecules with promising properties. In this study, we have evaluated novel formulations of existing explosives with the intention of developing high explosives with small critical diameters and low shock sensitivities while maintaining high performance. Specifically, 1,1-diamino-2,2-dinitroethene (DADNE or FOX-7) or 3,3'-diamino-4,4'-azoxyfurazan (DAAF) was formulated with 3-nitro-1,2,4-triazole-5-one (NTO) to determine what weight percentage of added DADNE or DAAF yielded steady detonation near predicted values at 12.7 mm diameter. Preparation, purification and characterization have been performed for two mono-molecular explosives, 5,7-diamino-4,6-dinitrobenzofuroxan (CL-14) and 1-nitroso-3,5-dinitro-1,3,5-triazacyclohexane (m-RDX or mononitroso-RDX). A new, one-pot synthesis of m-RDX has produced a 59{\%} yield with limited RDX contamination. Results from small-scale sensitivity tests on CL-14, m-RDX and NTO-based formulations, and rate sticks will be discussed. [Preview Abstract] |
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