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Abstract:The derived ways of empiric-order autocatalytic reaction rate equation and its thirteen derived formulae were presented The equation of rate curve characteristics [α_max and (dα/dt)_max] and the equation of change in reaction extent (α) with time (t) and temperature (T) describing the autocatalytic reaction were derived. The computer program of calculating the kinetic parameters (E, A or E₁, A₁, E₂, A₂) and empiric-order (m, n, p) of autocatalytic reaction and the values of α_max and (dα/dt)_max was written. The rate equation describing the autocatalytic decomposition reaction of hexanitrohexaazaisowurtzitane (HNIW) and the kinetic parameters, catalytic coefficient K_cat, rate curve characteristic parameters and the equation of change in α with t describing the autocatalytic decomposition reaction of nitrocellulose (NC) (12.82%, 12.97%, 13.54%, 13.61%, 13.88%, 14.14% N) were presented.

Abstract:Basic properties of the thermal decomposition reaction of ammonium dinitramide (ADN) were introduced. Theoretical investigation results of ADN decomposition reactions were summarized. The effect of solvent on the decomposition behavior of AND in the DN^- model was analyzed. The advantage of path for decomposition of different proton transfer isomers in dinitramide acid (HDN), HDN₂ and ADN₂ cluster model and the effects of the double proton transfer process of the intramolecular and intermolecular on the formation and decomposition reaction of different isomers were compared. The reason of trace water in (H₂O)_n…NH₄⁺[ON(O)NNO₂]^-(n=1, 2, 3)and ADN₂ cluster model on the abnormal decomposition behavior of ADN was discussed. Different theoretical model reveals the essence of the decomposition reaction of ADN to a certain extent, the kinetic parameters obtained in the larger ADN_n clusters agree with the experimental results well. Study shows that the introduction of the QM-MM method, which is suitable for the larger ADN_n clusters and solvation model in the liquid phase and gas phase, will play an important role to obtain the relevant thermodynamic and kinetic parameters of ADN involved in the application process.

Abstract:The single crystal of 1-amino-biurea was obtained by slow evaporation method in solvent and its structure was determined using X-ray single crystal diffraction analysis. Based on the single crystal data of biurea and 1-amino-biurea, their charge distribution, natural bond orbit and molecular electrostatic potential were calculated to study their electronic structures and properties by DTF-B3LYP method with the cc-pVTZ basis set. Mulliken charge distribution data exhibits that O atoms have the most Mulliken charge of -0.3470e, followed by N(2A) and N(2) atoms (-0.2371e) in biurea, and O(1) atom (-0.3700e) has the most Mulliken charge, secondly O(2) atom (-0.3449e) and thirdly N(5) atom (-0.2399e) in 1-amino-biurea. Furthermore, the datas of NBO charge distribution and the molecular electrostatic potential show the same trend with that of Mulliken charge distribution. All the calculated results show that the O, N(2) and N(2A) atoms of biurea and O(1), O(2) and N(5) atoms of 1-amino-biurea are the most probable coordination site.

Abstract:Packing structures of the reported CL-20, HMX, BTF and TNT cocrystals were studied by Hirshfeld surface and fingerprint plot from densities, packing coefficients and molecular interaction contributions. Results show that the packing coefficients of most energetic cocrystals are between their conformers. Energetic molecules in different energetic cocrystals possess different intermolecular interactions with neighboring molecules. The total percentage of O…H and O…O in CL-20 cocrystals are more than 70%, indicating the two interactions making cocrystals stable. O…H in HMX cocrystals plays an dominant role with the amount of more than 50%. C…O and C…C in BTF cocrystals and TNT cocrystals are more than that in CL-20 cocrystals and HMX cocrystals, which proves π packing is obvious in BTF cocrystals and TNT cocrystals.

Abstract:To study the migration and diffusion phenomena of nitrates nitroglycerine(NG) and 1, 2, 4-butanetriol trinitrate (BTTN) as plasticizers in polyurethane elastomer under mesoscopic scale, the dissipative particle dynamics(DPD)simulation calculation was performed by molecular simulation software Materials Studio. A mesoscopic model of coarse graining was established. The diffusion coefficient of NG and BTTN in polyurethane elastomer was calculated by this model. Mesoscopic diffusion coefficient obtained by calculation is 1.80×10^-12 m²·s^-1 for NG, 0.21×10^-12 m²·s^-1 for BTTN, which is at the same level with microscopic results reported in literature, i.e. 0.65×10^-12-11.10×10^-12 m²·s^-1 for NG. After rising of molecular weight of prepolymer and temperature, the diffusion coefficients of nitrates increase. But the diffusion coefficient decreases with increasing the nitrate content. The diffusion coefficient of NG is bigger than that of BTTN under same conditions. The mesoscopic molecular simulation results agree with the reported values in literature and theoretical trend, indicating that the established coarse graining model of nitrate/ polyurethane can be used to investigate the diffusion case of the two nitrates in polyurethane.

Abstract:Under the standard condition (ratio of chamber pressure to exit pressure (p_c:p_e) is 70/1), the energy parameters of HTPB and CMDB propellants containing hydroxylammonium 2-dinitromethyl-5-nitrotetrazole (HADNMNT) were calculated by minimum free energy method. The density impulse of the HADNMNT monopropellant is 4936.4 N·s·cm^-3, which is higher to that of the RDX and lower to HMX and CL-20. Replacing AP with HADNMNT in HTPB propellant can increase specific impulse by 428.7 N·s·kg^-1. The iso-impulse trigonal figure of the HTPB propellant is drawn out, and the relationship between specific impulse and ingredients was discovered. The impulse of HTPB propellant is up to 2778.9 N·s·kg^-1, when the mass fractions of HTPB, HADNMNT, RDX and Al powder are 10%, 60%-62%, 14%-16% and 14%-15%, respectively. Replacing RDX with HADNMNT in smokeless CMDB propellant, the specific impulse increases to 2522.9 N·s·kg^-1. Moreover, the specific impulse of CMDB propellant can be remarkably improved through adjusting the mass fractions of HADNMNT and Al powder. The impulse of CMDB propellant reaches 2598.5 N·s·kg^-1, when the mass fractions of NC, NG, HADNMNT, Al, DINA and Al powder are 25%, 33%, 11%, 20%, 3.5% and 7.5%, respectively.

Abstract:To explore the effect of graphene on the reaction mechanism of nitromethane (NM), three kinds of initial reactions of NM on grapheme surface including the NM-methyl nitrite(MN) rearrangement reaction, the H-migration rearrangement reaction, and the C—N homolytic cleavage reaction were investigated by the ONIOM (our Own N-layer Integrated molecular Orbital and molecular Mechanics) method. Results show that the structures and energies of initial reaction transitions states of NM and reaction products are influenced by the graphene surface. The graphene surface makes the activation energy of three kinds of initial reactions decrease 13.4 kJ·mol^-1, increase 3.8 kJ·mol^-1 and 5.4 kJ·mol^-1 in the order. The orders of activation energies change from the C—N homolytic cleavage < the H-migration rearrangement < the NM-MN rearrangement to the NM-MN rearrangement < the C—N homolytic cleavage < the H-migration rearrangement. The reaction transition states and reaction products tend to form planar and eclipsed structures, respectively, leading to the maximization of interactions with graphene surface.

Abstract:2,2,6,6-Tetranitroadamantane was synthesized by direct oxidative nitration from adamantane-2,6-dionedioxime, which was prepared via oxidation and oximation of adamantane. The structures of the products were confirmed by ¹H NMR, ¹³C NMR, IR and elementary analysis. The reaction conditions of the oxidative nitrition were optimized as following: n(adamantane-2,6-dionedioxime):n(dinitrogen pentoxide)=1:6, reaction solvent CH₂Cl₂, reaction temperature 50 ℃ and reaction time 30 min, with the yield of 50%. The thermal properties of 2,2,6,6-tetranitroadamantane were analyzed by thermogravimetry (TG) and differential scanning calorimetric (DSC) measurements. Results show that its decomposition temperature is 275 ℃ and exothermic peak temperature is 298 ℃, which indicate that 2,2,6,6-tetranitroadamantane has good thermal stability.

Abstract:Using 3, 4-bis(3′-aminofurazan -4′-yl) furazan (BATF) as starting material, a novel energetic compound 3, 3′-azobis(3-amino-trifurazan) (ABATF) was synthesized by oxidation reaction, with the yield of 82%. The structure of ABATF was characterized by NMR, IR, MS and elemental analysis. The optimized conditions of oxidation reaction were obtained as follows: reaction time 20-30 min, molar ratio of BATF to KMnO₄ 1:1, reaction temperature 50 ℃. Thermal properties of ABATF were studied by differential scanning calorimetry and thermogravimetry-differential thermogravimetric. The detonation performances were calculated by Gaussian 09 and VLW equation of state for detonation. Results show that the maximum decomposition point is 295.5 ℃. The computed density is 1.765 g·cm^-3, explosion velocity is 8250 m·s^-1, enthalpy of formation is 1626.6 kJ·mol^-1, detonation pressure is 28.4 GPa and explosion heat is 6350 J·g^-1, indicating that the performance of ABATF is better than BATF.

Abstract:Dihydroxylammonium 1, 1′-diolate-5, 5′-bistetrazole (TKX-50) was synthesized with a total yield of 63% via the reactions of oximation, chloration, azidation-cyclization and neutralization using glyoxal as starting material, and its structure was characterized by NMR, MS, IR. The effects of solvent, temperature and reaction time of azidation-cyclization reaction to synthesize an important intermediate 5, 5′-bistetrazole-1, 1′-diol dihydrate were optimized, as well as the neutralization reaction from 5, 5′-bistetrazole-1, 1′-diol dehydrate to TKX-50. Results show that the optimal conditions for azidation-cyclization are determined as: mixed solvent of acetone-water at 0 ℃ for 1.5 h and then extracted by diethyl ether, and the extract liquor directly into hydrogen chloride gas with the yield up to 88%. And for the neutralization reaction, the optimal conditions are as following: solvent of acetic ether at 50 ℃ for 2 h, with the yield of 94%.

Abstract:When electron-deficient nitro-compounds interact with electron-rich fluorescent compounds of alkynyl substituted triphenylamines, it will cause the changes of the conjugate degree and the charge distribution of the fluorescent compounds, resulting in the change of fluorescence. Alkynyl substituted triphenylamines were designed and synthesized via sonogashira coupling reaction using alkynes and halogenated triphenylamines as raw materials. The effects of molecular structure, solvent polarity, and addition of nitro-explosives on the fluorescent properties of alkynyl substituted triphenylamine solution were studied by fluorescence analysis technique. Results show that with the increase of TNT concentration, the fluorescence intensity of the alkynyl substituted triphenylamines weakens gradually. When adding 2.5×10^-4 mol·L^-1 of TNT into 1×10^-5 mol·L^-1 of alkynyl substituted triphenylamine solution, the obvious fluorescence quenching effect occurs and when the concentration of TNT rises up to 1×10^-2 mol·L^-1, the fluorescence disappears completely. The quenching abilities of the alkynyl substituted triphenylamines to different nitro-explosive are different, so the alkynyl substituted triphenylamines are expected to become the sensitive materials for the detection of nitro-explosives.

Abstract:To improve mechanical properties of RDX based aluminized explosives, the RDX based aluminum fiber explosive was prepared by replacing aluminum powder in aluminized explosive with aluminum fiber. The fitting calculation of the elastic modulus and uniaxial compression strength of aluminum fiber explosive with different content of aluminum fiber obtained by quasi-static compression mechanical experiment was carried out. The relation expression of the elastic modulus and compression strength with aluminum fiber volume content for aluminum fiber explosive was obtained. Results show that the reinforcement coefficient of aluminum fiber obtained by fitting experimental data of elastic modulus is 8.19. The aluminum fiber can significantly enhance the mechanical properties of aluminum fiber explosive. With increasing the aluminum fiber content, its elastic modulus, compression strength and residual strength of aluminum fiber explosive increase When aluminum fiber volume content is 0%-30%, the critical strain of aluminum fiber explosive increases. When aluminum fiber volume content is higher than 30%, the critical strain of aluminum fiber explosive does not change The fitting of the engineering stress-strain curves of aluminum fiber explosive with aluminum fiber volume content of 10%-40% is performed by a normal distribution function, its fitting correction coefficient of determination is 0.987-0.998. The uniaxial compression strength of aluminum fiber explosive with specific aluminum fiber content of less than 38.1% for volume fraction can be calculated by the proposed relation.

Abstract:JO-8 and Composition B were investigated by low-speed impact loading test using the small hammer of 30 kg, and their impacting courses were studied by the high speed photography, and the residue after impacting were analyzed by the scanning electric microscopy(SEM). Results show that the ignition threshold of JO-8 is 360 N and that of Composition B is 300 N, which indicate that JO-8 has better anti-impact property than Composition B. Two explosives exercise shocking, plastic flowing, flying and reacting, and the reacting happens after the explosive is damaged with the residual explosive. The damage pattern of Composition B is focused on the interface debond and rupture across the crystal, and the JO-8 explosive is on the shear distort and rupture through the crystal. Because of the preparation process of Composition B, RDX is surrounded by TNT, and the lower mechanical properties of TNT cause the Composition B rupture under impact loading before that of JO-8. While the addition binder improves the brittle characteristics of the explosive HMX and made its damage pattern different from the composition B. The good compressed strength makes JO-8 explosive ignition delay.

Abstract:Ignition characteristics of Al micro-powders, Al nanopowders, Ti nanopowder and amine perchlorate(AP)/ hydroxyl-terminated polybutadiene(HTPB) composite solid propellants containing metal powders were studied by CO₂ laser ignition method with a wavelength of 10.6 μm at different heat fluxes, and the effects of Al size on ignition characteristics of Al powders and the effect of the different metal powders on ignition characteristics of AP/HTPB composite solid propellants containing metal powders were discussed under heat fluxes from 77.6 W·cm^-2 to 365.1 W·cm^-2. Results show that the ignition delay times of Al powders gradually decrease with the increasing of heat fluxes. The ignition delay time is shorter and the ignition energy is lower ( t_Jal-50 < t_N-Al < t_Jal-150 < t_Jal-200 < t_5μm and E_Jal-50 < E_N-Al < E_Jal-150 < E_Jal-200 < E_5μm)when the size of Al powder is smaller. The ignition energy and delay time of Ti powder is smaller than the Al powder when their size is 150nm and their ignition process are obviously different. The ignition of AP/HTPB composite solid propellants containing metal powders appears on the surface of the sample first, and the order of the ignition delay time is t_RX-0 > t _HT-5A > t _HT-1A > t _HT-4A > t _HT-3T and the order of the ignition energy is E_RX-0 > E _HT-5A > E _HT-1A > E _HT-4A > E_HT-3T, which is in accordance with the order of the ignition time of the corresponding metal powders(t_5μm > t _Jal-200 > t _N-Al > t _Jal-50 > t _Ti-150).

Abstract:3, 3′-Dinitroamino-4, 4′-azoxyfurazan (NOF) was prepared via nitration of 3, 3′-diamino-4, 4′-azoxyfurazan (AOF)as raw material using pure nitric acid. New two kinds of energetic ion salts, carbohydrazide 3, 3′-dinitroamino-4, 4′-azoxyfurazan (NOF-CBH) and aminoguanidine 3, 3′-dinitroamino-4, 4′-azoxyfurazan (NOF-AG), were synthesized via metathesis reaction with nitrogen-rich cation (CBH and AG). Their structures were characterized via NMR, IR and elemental analysis. The thermal behaviors of the compounds were studies by TG-DTG. The geometric configuration of NOF and its anion (NOF^2-) were compared and studied by quantum chemistry calculations. The detonation performances of NOF-CBH and NOF-AG were predicted. Results show that the initial decomposition temperatures of NOF-CBH and NOF-AG are 144.9 ℃ and 151.6 ℃ respectively, which are higher than 90 ℃ of NOF. The standard molar enthalpy of formation and density are 515.86 kJ·mol^-1 and 1.82 g·cm^-3 for NOF-CBH and 815.96 kJ·mol^-1 and 1.75 g·cm^-3 for NOF-AG. Their values of calculated detonation velocities are greater than 8500 m·s^-1.

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