Abstract:

Abstract:To study the rheological properties and to cure the reaction process of branched polyglycidyl azide （B-GAP）-based propellent， the slurries were tested by rheological research methods， and the changes of viscosity with shear rate and modulus with time at 50， 55， 60 ℃ and 65 ℃ were studied. The results indicate： B-GAP propellant slurry has a shear thinning properties and belongs to pseudoplastic non-Newtonian fluid； The curing reaction rate of the propellant slurry increases as the curing reaction progresses， reaching a maximum value when the curing degree is 0.3， and then the reaction rate begins to decrease until zero； Temperature has a great influence on the kinetics of propellant curing reaction. Within a certain temperature range， the peak value of the curing reaction rate increases with the increase of temperature， and the maximum value of storage modulus decreases with the increase of temperature； Based on the power law equation and Arrhenius equation， the constitutive equation and curing kinetic reaction equation of B-GAP slurry was obtained.

Abstract:Aiming at the problem that the cohesive zone model parameters， describing the mechanical properties of the adhesive interface， which can′t be obtained by traditional experimental method accurately，the inversion research on the relevant parameters of bilinear cohesive zone model used for the adhesive interface is carried out by using the digital image correlation method and Hooke-Jeeves optimization algorithm based on the tensile test results of solid rocket motor rectangular adhesive specimens. The inversion results show that the maximum adhesive strength， modulus and failure fracture energy are 0.55 MPa， 0.57 MPa and 2.26 kJ·m^-2， respectively， when the tensile rate is 5 mm·min^-1. The relative error of simulated and measured stress-strain curves is corrected from 44.7% to 4.3%. When the tensile strain is 0.05 and 0.08， the maximum displacement errors of simulated and measured region of interest is 0.64 mm and 1.76 mm， respectively， and the average displacement errors of simulated and measured region of interest is 0.38 mm and 0.45 mm， respectively. The validation results indicate that the accuracy of the inversion identification method is high enough and the established cohesive zone model can be used to characterize the mechanical properties of the adhesive interface.

Abstract:To improve the hazard classification of anhydrous hydrazine， the extremely insensitive detonating substance （EIDS） gap test and external fire test were conducted for the standard packaging anhydrous hydrazine （18 kg and 120 kg） in accordance with the United Nations “Recommendations on the Transport of Dangerous Goods， Manual of Tests and Criteria”. The deflagration process， the highest temperature of the fireball surface and shock wave effect of samples were obtained by a high-speed camera， an infrared thermal imaging and a shock wave pressure acquisition system. The experimental results show that， under external fire conditions， the TNT equivalence of the anhydrous hydrazine-18 kg was 0.724， which was 1930.67 times that of anhydrous hydrazine-120 kg. Under certain conditions， anhydrous hydrazine has obvious explosive properties and can be assigned to Division 1.1 C or Division 1.3 C for different packaging design pressures. The hazard class of anhydrous hydrazine is closely related to the standard packaging design pressure. For safety purposes， the design pressure of packaged anhydrous hydrazine should be properly reduced within the allowable range to effectively reduce its hazard.

Abstract:The new challenge to the existing coating layer process was put forward by the development of solid rocket motor technology. In recent years， thermosetting resin as the matrix was used， combined with continuous automatic coating technology， the popular coating production method of coating layer lies in whether complete molding and excellent performance can be obtained quickly. The flow properties and casting condition of unsaturated polyester （UPR） coating layer were studied. The chemical rheological model of the UPR coating layer during continuous automatic manufacturing is obtained by introducing exponential function based on Kinua-Fontana model. The functional relationship of viscosity versus time and temperature of cured UPR is established. The suitable temperature for casting operation was obtained. The filling volume fraction distribution， flow rate distribution and weld line position of coating layer were predicted by introducing of POLYFLOW simulation software， which the constitutive equations is established on the base of Bird-Carrea power-law equation. The casting process was simulated at the constant rate and pressure， respectively. The results show that the casting temperature is below 35 ℃， the casting pressure is more than 1 MPa， and the inlet flow rate is more than 150 mm³·s^-1 and less than 175 mm³·s^-1 in the coating layer casting process.

Abstract:The aim of this study is to explore the effect of absorption coefficient on propulsion performance of the laser ablated ammonium dinitramide （ADN）-acetone based liquid propellant. ADN and absorbent were mixed with different proportions in the range of 0-80% and a proportional distance of 10% to form ADN-acetone based liquid propellants. The absorption coefficients of propellants with different proportions were measured and calculated using a near-infrared spectrometer. Under the laser energy of 60 mJ and liquid film thickness of 300 μm condition， the impulses generated by laser ablation of propellants with different proportions were measured using a high-precision torsion pendulum. Results show that the absorption coefficient decreased with the increase of ADN content. In addition， the impulse decreased after peaking at ADN content of 30%， but increased again at ADN content of 80% sharply. The decrease of impulse in the ADN content range of 30%-70% is mainly caused by the decrease of absorption coefficient which leads to the decrease of laser energy deposited by the propellant. The impulse increase at ADN content of 80% is caused by the propellant whose absorption coefficient approaches to 0 and constitutes a “water cannon target” with the container. After the container is ablated by the laser， the propellant will act as a constraint， and result in the increase of impulse.

Abstract:High purity 2，4，6-trinitro-5-ethoxy-1，3-phenylenediamine （DATNEB） can be used as an internal standard in high performance liquid chromatography （HPLC） to accurately analyze the purity of TATB synthesized by the chlorine-containing method. To study the synthesis and energetic properties of DATNEB， high purity DATNEB was prepared from picric acid by aminating with 4-amino-1，2，4-triazole （ATA） and then ethylating with triethyl orthoformate. The overall yield was 32.5% and the purity was over 99.8%. The structure of the product was characterized by IR， ¹H NMR， ¹³C NMR， MS and X-ray single crystal diffraction. The mechanisms of amination and ethylation were discussed， the thermal and detonation properties of DATNEB were also studied. The results show that DATNEB crystallizes in a monoclinic system， space group P2₁/c with a=1.21261（7） nm， b=0.89654（4） nm， c=1.12310（6） nm， V=1.17675（11） nm³， Z=4， ρ=1.62 g·cm^-3. DATNEB exhibits an endothermic peak at 193.9 ℃ and exothermic peak at 236.0 ℃， indicating a good thermal stability. It has a detonation velocity of 7.05 km·s^-1 and detonation pressure of 21.14 GPa，which is comparable to TNT， while the sensitivityis much lower than that of TNT and RDX. Therefore， the synthesized high-purity DATNEB can not only be used as an internal standard， but also an auxiliary component of molten-cast explosives.

Abstract:In order to explore the infrared extinction properties of three-dimensional graphene， three-dimensional （3D） graphene powders were prepared by thermochemical deposition method. The morphological and structural characteristics of the three-dimensional graphene powder were confirmed by electron microscopy and X-ray diffractometer， and the dispersion properties were tested by using a comprehensive powder characteristic tester. Then the infrared extinction properties of three-dimensional graphene were tested by using smoke chamber test， and compared with the extinction properties of composite graphite and carbon fiber under the same test conditions. The results show that the infrared extinction performance of three-dimensional graphene is excellent. The average mass extinction coefficients are about 1.32 m²·g^-1 and 1.09 m²·g^-1 in the infrared wavelength range of 3-5 μm and 8-14 μm， respectively. Compared with composite graphite and carbon fiber， the average mass extinction coefficients of 3-5 μm are improved by 57% and 132%， respectively. And the average mass extinction coefficients of 8-14 μm are improved by 35 % and 102 %， respectively. It can be seen that 3D graphene shows better infrared extinction ability.

Abstract:In order to improve the activity of hydrogenolytic debenzylation catalyst and reduce the dosage of noble metal palladium during the synthesis of hexanitrohexaazaisowurtzitane（CL-20）， carbon supports were prepared by ball-milling/carbonization method using sodium gluconate as a raw material. The effects of carbonization temperature， heating rate and additive addition of sodium gluconate on the support structure and the catalytic activity of the corresponding Pd（OH）₂/C catalysts in the hydrogenolytic debenzylation of hexabenzylhexaazaisowurtzitane（HBIW） and tetraacetyldibenzylhexaazaisowutzitane（TADB） were explored. The pore structure， particle morphology， crystal phase structure， chemical composition and surface chemical properties of carbon supports were characterized by nitrogen sorption isotherm measurement（BET）， scanning electron microscope（SEM）， transmission electron microscopy（TEM）， powder X-ray diffraction（XRD）， element analysis and temperature programmed desorption （TPD）. The results show that the optimized carbonization condition of sodium gluconate was calcination at 700 ℃ with a heating rate of 10 ℃·min^-1 in the presence of additive， NaHCO₃， which could adjust the puffing carbonization of sodium gluconate. The received carbon supports have rich hierarchical pore structure and appropriate amount of surface oxygen containing groups， and the corresponding Pd（OH）₂/C catalysts exhibit high activities in the hydrogenolytic debenzylation reaction of HBIW and TADB.

Abstract:The fluorescence properties and fluorescence stability of 2，4，8，10-tetrabroitro-benzopyrido-1，3a，6，6a-tetraazapentylene （BPTAP） were comprehensively investigated. The spectral properties of BPTAP in different solvents （acetonitrile， methanol， tetrahydrofuran， acetone， trichloromethane， ethyl acetate， N"-N"-dimethylformamide， dimethyl sulfone）， content of water （0-100%）， pH （2.0-12.0） were studied in detail. The effects of light， temperature and pH value on the fluorescence stability of BPTAP solution were investigated， and the mechanism of fluorescence decay of BPTAP solution was analyzed by ultra performance liquid chromatography-high resolution mass spectrometry （UPLC-HRMS）. The results show that although BPTAP has four nitro groups， it exhibits strong green fluorescence in some organic solvents. The fluorescence intensity of BPTAP in acetonitrile is the highest， and its maximum absorption/emission wavelength is 460 nm/508 nm. Low content of water （≤10%） can increase fluorescence intensity of BPTAP， while high content of water （>10%） decrease the fluorescence of BPTAP sharply. BPTAP has higher fluorescence in acidic， neutral and weak alkaline conditions. When the pH value is above 9.0， the fluorescence of BPTAP decreases rapidly with the increase of pH value. BPTAP shows good stability in room temperature and natural light. The closer the light wavelength is to the maximum absorption wavelength of BPTAP and the higher the temperature， the worse the fluorescence stability of BPTAP. The increase of pH value not only reduces the fluorescence intensity of BPTAP， but also accelerates the decline of BPTAP fluorescence. The mechanism of fluorescence decay of BPTAP under alkaline condition is based on nucleophilic substitution. The nitro group at para site of pyridine ring is replaced by the hydroxyl group in alkaline solution to form a new compound 1 （the elemental composition ［M-H］^- is C₁₁H₃N₈O₇）.

Abstract:Boron-based hypergolic ionic liquids， which exhibited low viscosity， short ignition delay time and low cost， were considered as the powerful candidate for conventional liquid propellants. Here， the research progress of design， synthesis and physical chemical properties on boronium-anion-based HILs were systematically reviewed. The theoretical and applied studies including thermal decomposition， hypergolic reaction， combustion mechanism and relationship between structure and performance were briefly summarized. The practical application and development tendency of boronium-anion-based HILs were also discussed．

Abstract:High-energy-density hydrocarbon fuels are important aerospace power source， which mainly developing direction is high-energy and green， especially under the requirements of low carbon and sustainable development， the green synthesis of high-energy-density hydrocarbon fuel becomes essential. The green synthesis technology of high-energy-density hydrocarbon fuel has been reviewed. Compared with traditional synthesis of JP-10 （exo-THDCPD） and Adamantane， the advanced synthesis for fuel is improved by changing the synthesis route or using green catalysts such as solid acids and ionic liquids. Using biomass as feedstock is another strategy for green synthesis， covering terpenoids and lignocellulose-derived platform molecules such as cyclic ketones/alcohols， furanic aldehydes/alcohols， etc.， and the alternative fuels such as bio-based RJ-4（endo-THDMCPD and exo-THDMCPD） and JP-10 have been synthesized. In addition， the photocatalytic technology is used to synthesis of fuel with high tension and polycyclic structures from the perspective of green synthesis process view point， an outlook on further development of high-energy-density hydrocarbon fuel is also given. This review article will be helpful to explore and develop better approach and process for the synthesis of high-energy-density hydrocarbon fuel and upgrade for advanced aerospace vehicles.

Abstract:Bridged nitrogen-rich heterocyclic energetic compounds are of the rich diversity， good thermal stability and excellent energy density. They are potential materials with high energy density and have been widely studied and reported by scholars all over the world. Among them， the imino group （—NH—）， which acts as bridged unit， can not only improve the enthalpy of formation and energy density， but also reduce the sensitivity by the formation of hydrogen bonds through the bridged imino group， thereby constructing high-energy and low-sensitivity energetic materials. This paper introduces the research progress of imino-bridged nitrogen-rich heterocyclic energetic molecules and their salts， and reviews the preparation methods， physicochemical properties and detonation properties of these energetic compounds， the future development potential and research trend of imino-bridged nitrogen-rich heterocyclic compounds are prospected， so as to provide a reference for the design and synthesis of imino-bridged energetic compounds.