Studies on 3-Amino-4-(1H-tetrazol-5-yl)-furazan:Crystal Structure,Thermal Behavior and Energetic Performance

The structure of 4-amino-3-(5-tetrazolate)-fiirazan(HAFT) was characterized by single crystal X-ray diffraction. The thermal decomposition process of HAFT was investigated by MS-FTIR-DSC-TG coupling technique. The result shows that the exothermic process occurs from 278.7-350℃, with a peak temperature of 324.7℃. The thennal decomposition gaseous products of HAFT are NO2, CO2, HCN, CO, NH3 and H2O. The detonation velocity and detonation pressure of HAFT were calculated by the nitrogen equivalent equation. The detonation velocity of HAFT is 7727.46 m/s, which is higher than that of TNT(7178 m/s). The detonation pressure of HAFT(25.27 GPa) is satisfactory. The sensitivity tests reveal HAFT possesses excellent insensitivities to impact and friction.     

Fatigue crack initiation life of fine grain brass H62

Fine grain alloys possess excellent properties entailing high strength and toughness. Fine brass H62 is made by re-crystallization with grain size ranging from 5 to 10 μm. Fatigue initiation life is investigated from specimens tested on Instron 1341 machine a frequency of 30 Hz. Furthermore fatigue crack initiation life of this fine brass H62 is predicted by the energetic approach. It is found that: (1) the finer the grain size, the longer the fatigue life, which is due to its higher toughness; (2) intergranular cracking is the main mechanism of fatigue failure. Concave pits were found in the zone of fatigue crack propagation; and (3) the energetic approach gave acceptable fatigue crack initiation life estimation.     

基于表面占位效应和合理动力学模型的电催化火山关系

电催化在水电解、燃料电池等能源和环境领域起着至关重要的作用.电催化火山关系是预测和理解催化剂活性趋势的通用和标准工具.N?rskov等提出的基于最大反应自由能(ΔG0max)的现代电催化火山关系理论,由于未充分考虑电极电位、中间体及毒物的表面占位以及溶液pH等对电催化动力学的影响,在高活性催化剂的准确预测方面存在局限....     

The Specific Impulse as an Important Parameter for Predicting Chemical High Explosives Performance

The plate dent test is one of the most useful tools used by experimenters for the determination of explosive performance. However, performing the test for every new composition is certainly tedious and time consuming. Hence, the aim of the present study was to introduce a model from which the plate dent performance output could be predicted. Using three set of variables namely, the loading density ρ, oxygen balance Ω and the specific impulse I_sp (calculated according to the [H₂O‐CO₂] arbitrary decomposition assumption), a correlation was derived, which is capable of reliable prediction of the dent depth δ produced on 1018 cold‐rolled steel by a detonating explosive cylinder. Furthermore, the calculated δ values and the well‐known Kamlet‐Jacobs and Keshavarz‐Pouretedal methods were used to estimate the detonation pressure P of CHNOClF‐containing explosives, and the results of each were then compared to experimental/thermochemical code data. The root‐mean square deviation (RMSD) analysis clearly shows that the proposed model is more reliable to predict P than the Kamlet‐Jacobs method especially for fluorine and chlorine‐containing compositions.     

Controlling the electrostatic discharge ignition sensitivity of composite energetic materials using carbon nanotube additives

Powder energetic materials are highly sensitive to electrostatic discharge (ESD) ignition. This study shows that small concentrations of carbon nanotubes (CNT) added to the highly reactive mixture of aluminum and copper oxide (Al + CuO) significantly reduces ESD ignition sensitivity. CNT act as a conduit for electric energy, bypassing energy buildup and desensitizing the mixture to ESD ignition. The lowest CNT concentration needed to desensitize ignition is 3.8 vol.% corresponding to percolation corresponding to an electrical conductivity of 0.04 S/cm. Conversely, added CNT increased Al + CuO thermal ignition sensitivity to a hot wire igniter.     

Energetic polymers as binders in composite propellants and explosives

The principles behind the use of polymeric binders in composite propellants and explosives are described with emphasis on the properties which they should possess in order to satisfy the requirements for inclusion in a composition. The desirability of using energetic polymers as binders in terms of both performance and safety, and the problems associated with their preparation and properties, are discussed. The contributions of chemical synthesis within DRA to overcome these problems will be shown. Preparation of energetic polymers both by polymer modification and by polymerization of an energetic monomer is described. We have developed three energetic polymers: poly-3-nitratomethyl-3-methyloxetane (polyNIMMO), polyglycidyl nitrate (polyG-LYN) and nitrated hydroxy-terminated polybutadiene (NHTPB). Two of these (polyNIMMO and polyGLYN) have shown excellent properties in propellant and explosive formulations and proved that low-vulnerability, high-performance compositions are possible. The properties of the products from our work are compared with those of other groups and a glimpse of the future in this area is given to show the potential for new energetic polymers.     

Adsorption of propane andn-butane on polystyrene adsorbents

Summary The adsorption isotherms of propane andn-butane adsorbed on two polystyrene adsorbents with high and low specific surface areas were measured in the concentration range from 500 ppm to 10 800 ppm in a helium carrier gas at 273, 298, 303, and 313K. The isotherms can be represented by either a Freundlich or a Langmuir-Freundlich type equation. The energetic heterogeneities of the two adsorbents were characterized in terms of the dispersion of the adsorption energy. Also, the isosteric heats were calculated from the dimensionless adsorption capacities.

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Adsorption von Propan undn-Butan auf Polystyrol-Adsorbentien

Zusammenfassung Es wurden die Adsorptionsisothermen von Propan undn-Butan an zwei Polystyrol-Adsorbentien mit hohen und niederen spezifischen Oberflächen im Konzentrationsbereich von 500 bis 10 800 ppm in einem Helium-Trägergas bei 273, 298, 303 und 313 K gemessen. Die Isothermen können entweder mittels Gleichungen vom Freundlich- oder Langmuir-Freundlich-Typ dargestellt werden. Die energetische Heterogenität der zwei Adsorbentien wurde in Termen der Dispersion der Adsorptionsenergie charakterisiert. Es wurden auch die isosterischen Adsorptionswärmen aus den dimensionslosen Adsorptionskapazitäten berechnet.

     

Thermal ageing of rocket propellant formulations containing ε-HNIW (ε-CL20) investigated by heat generation rate and mass loss

New types of rocket propellant batches have been formulated with the objective of achieving higher burning rates. The main ingredients are (1) the energetic plasticizers glycidyl azide polymer-α,ω-diazide (GAP)-A (short chain GAP with azide end groups), trimethylolethane trinitrate (TMETN) and 1,2,4-butanetriol trinitrate (BTTN), (2) the energetic substances ammonium perchlorate (AP) and ε-CL20 (ε-HNIW, hexanitrohexazaisowurtzitane, crystallised in ε-phase). The binder is GAP (glycidyl azide polymer, diol component) cured with the polyisocyanate Desmodur™ N100. From the point of view of stability and ageing, the interesting fact is that the formulations contain none of the typical stabilisers for the nitric acid ester components TMETN and BTTN, although their contents range up to 21 mass%. One reason for doing so is to increase the content of the high energy ingredients. Seven formulations were examined in more detail. To assess basic stability the autoignition temperature test, Dutch mass loss test and vacuum stability test were used. To investigate ageing, two measurement quantities are applied: heat generation rate (heat flow) as function of time at 70, 80 and 89 °C and mass loss as function of time at the temperatures of 70, 80 and 90 °C. The evaluation of the measurements was done with reaction kinetic models. One batch (#189) containing BTTN shows significantly lower activation energy and pre-exponential factor. From mass loss one gets as activation energy for #189 of 101 kJ mol⁻¹ in comparison to the range of 126-135 kJ mol⁻¹ for the six other batches. But, based on the ageing caused by chemical decomposition reactions, all seven batches showed a good ageing behaviour. A use time period of up to 20 years of use seems realistic.     

用多声子迁移模型理论研究硝基甲烷的分解机理

基于多声子迁移模型理论分析了撞击诱导硝基甲烷单分子分解反应可能存在的合理的反应路径。发现：对最低三态和基态的分子选择门模式分别为407cm-1,436cm-1和482cm-1, 616cm-1时,计算得到的相同时间长度上的能量迁移参数分别为5.43×105 J/mol*K ,5.82×105 J/mol*K 和8.22×105 J/mol*K,6.43×105 J/mol*K。而理论计算CH3NO2分子从基态跃迁致最低三态所需能量为2.39×105 J/mol,最低三态分子从C-N键断裂分解为硝基和甲基所需活化能为3.69×105 J/mol;基态的CH3NO2分子从C-N键断裂生成硝基和甲基所需能量为2.24×105 J/mol。因此,能量迁移能够提供足够的能量使CH3NO2分子在基态或者在跃迁至最低三态后从C-N键断裂生成硝基和甲基。这个结论与实验报道的结论基本一致。     

含能配合物[Pb(AZTZ)(bpy)(H2O)·2H2O]n合成、结构及燃烧催化性能

设计合成了含能配合物[Pb(AZTZ)(bpy)(H2O)·2H2O]n(1)(AZTZ=5,5’-偶氮四唑阴离子, bpy=2,2’-联吡啶), 用X射线单晶衍射法测定了其分子结构. 该晶体属三斜晶系, P1空间群, a=0.7341(6) nm, b=1.0050(8) nm, c=1.3367(1) nm, α=95.354(1)°, β=101.450(1)°, γ=101.233(1)°, V=0.8927(1) nm3, Z=2, S=1.030. 利用元素分析、红外光谱以及热重分析等手段对标题化合物进行了表征, 并研究了配合物(1)对固体双基推进剂的燃烧催化作用. 结果表明, 配合物(1)可以有效地提高固体双基推进剂的燃速.