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Abstract:To study the effects of particle size and content of Al powders on the particle damping generated by nitrate ester plasticized polyether (NEPE) propellant combustion products, the condensed phase combustion products of NEPE propellant were collected by a sealed bomb method and the particle size analysis was performed. The particle damping of combustion products on acoustic instability was calculated according to the theory of Culick linear particle damping. Results show that the particle size and content of Al powders significantly affect the particle damping of NEPE propellant combustion products on acoustic instability combustion, which mainly is due to the particle size and content of Al powders affect the particle size distribution of condensed phase combustion products. For a certain frequency acoustic instability combustion, the higher the mass fraction of particle in [1/2D_opt, 2D_opt] particle size interval in the condensed phase combustion products is, the greater the efficiency coefficient of particle damping of combustion products is, the larger the produced particle damping is. The mass fraction of condensed phase combustion products in combustion products is one of the factors determining the scale of particle damping, and which is positively correlated with the content of Al powders in propellant.

Abstract:The reactions of 8 newly synthesized ionic liquids containing BH₃(CN)BH₂(CN)^- anion, (I.L.1～ I.L.8), with white fuming nitric acid (WFNA) and red fuming nitric acid (RFNA) respectively were tested by using the long focus microscope-high speed photography technique and droplet method test device, respectively. Results show that each test achieves stable hypergolic reaction and two different flame development processes were observed. Specifically, after the contact of I.L.8 with WFNA, the microexplosion is occurred and hypergolic ignition is occurred in a short time, while after the contact of I.L.8 with RFNA the aplashing of secondary droplet is occurred. Due to the effect of Leiden Frost effect, the foam like droplets after reaction is rebounded and a short combustion reaction is appeared, the hypergolic ignition is occurred after a long time. For the ionic liquid with same heterocyclic core, the ignition delay time of the ionic liquid containing the allyl group on the side chain is the shortest, followed by the ionic liquid containing ethyl, while the ignition delay time of the ionic liquid containing butyl and WFNA is the longest. For the ionic liquid with the same side chain, the ignition delay time of the ionic liquid containing the pyridine heterocyclic ring is the longest, followed by the imidazole heterocyclic ionic liquid, and the ignition delay time of the ionic liquid containing tetrahydropyrrole reacted with WFNA is the longest.The higher the enthalpy of formation is, the shorter the ignition delay time is.

Abstract:To study the thermal degradation mechanism of polyether polytriazole (PTPET) and polyether urethane (PET) elastomers, the thermal degradation kinetics, gas phase and condensed phase products of PTPET and PET elastomers were analyzed by thermogravimetric analysis (TG), FTIR (Fourier transform infrared), TG-FTIR combined technology. The results show that the thermal degradation of PET elastomer is divided into two stages. The section from 275-350 ℃ is the first stage, and the section above 350 ℃ is the second stage. The thermal degradation of PTPET elastomer is only one stage, and the initial degradation temperature is 341 ℃. The initial thermal degradation temperature of PTPET elastomer is significantly higher than that of PET elastomer. The change rule of thermal degradation activation energy with the extent of conversion for PET and PTPET elastomers is obtained by a kinetic analysis method. The average value of thermal degradation activation energy of PTPET elastomer is about 290 kJ·mol^-1, and the maximum value of thermal degradation activation energy for PET elastomer is about 150 kJ·mol^-1. The initial thermal degradation of PET elastomers starts with the cleavage of urethane bond. The thermal degradation of the triazole ring of PTPET elastomer starts with the cleavage of the C—N bond, its thermal stability is better than urethane bond.

Abstract:To clarify the reaction process of 3, 3-diazidomethyloxetane(BAMO)-tetrahydrofuran(THF) copolymer(PBT) binder with commonly used curing agents, the curing reaction kinetics at 50-80 ℃ of PBT/ polyisocyanate (N100), PBT/toluene diisocynate (TDI) and PBT/TDI/N100 systems under catalyzing of TPB were studied by FT-IR spectroscopy. Results show that the PBT/N100 system follows the second order reaction kinetic law during the whole curing process, its apparent activation energy is 63.10 kJ·mol^-1, and the pre-exponential factor A is 1.63×10⁷ h^-1. The whole curing process of systems containing TDI is divided into two stages, but their mechanism is different.The PBT/TDI system follows the second order reaction kinetic law during the whole curing process, but is clearly divided into two stages at the conversion ratio of 60%, the conversion ratio of the first stage is less than 60% and the conversion ratio of the second stage is higher than 60%, due to differences in the activity of NCO on TDI. The reaction rate of the first stage is faster than that of the second stage at the same temperature. For the first stage, the apparent activation energy is 54.71 kJ·mol^-1, and the pre-exponential factor A is 4.38×10⁷ h^-1. For the second stage, the apparent activation energy is 56.50 kJ·mol^-1, and the pre-exponential factor A equals 1.24×10⁷ h^-1. For the PBT/TDI/N100 system, whose curing process is also divided into two stages at the conversion ratio of 65% due to the differences in the activity of —NCO on TDI and N100. During the first stage, the conversion ratio of less than 65% occurs the expansion chain of TDI, and the curing process follows the second order reaction kinetics, the apparent activation energy is 71.17 kJ·mol^-1, and the pre-exponential factor A is 4.58×10⁸ h^-1, the conversion ratio of —NCO of more than 65% mainly occurs crosslinking reaction of N100, the reaction rate is controlled by diffusion. When TDI and N100 are mixed, the pre-exponential is 28, 10, 37 times larger than single N100 and the two stages of single TDI, respectively, indicating that the active sites increase after the combination of curing agents.

Abstract:Using self-synthetic 1, 4-diamino-3, 6-dinitropyrazolo[4, 3-c]pyrazole as raw material, a high energy material 1, 4-dinitramino-3, 6- dinitropyrazolo[4, 3-c]pyrazole(DNANP) was synthesized via the nitration. Its twelve organic energetic salts were prepared via the neutralization and metathesis reactions of DNANP and organic amine. The structures of target compounds were characterized by IR spectrometry, ¹H NMR, ¹³C NMR, elemental analyses, mass spectrometry etc. The single crystal of DNANP·CH₃COOH was obtained and the crystal structure was analyzed. The thermal performances of DNANP and its energetic salts were analyzed by DSC. The detonation performances of target compounds were predicted using CBS-4M method of Gaussian 09 program and Kamlet-Jacobs equations. Rsults show thate thermal decomposition peak temperatures of DNANP and its twelve energetic salts are 133.28, 176.66, 178.45, 155.52, 156.90, 144.78, 160.86, 155.60, 159.05, 198.90, 158.10, 173.06 ℃ and 157.41 ℃, respectively. Their densities are from 1.71 g·cm^-3 to 1.92 g·cm^-3, the detonation velocities are from 7.690 km·s^-1 to 9.463 km·s^-1 and the detonation pressures are from 25.9 GPa to 41.8 GPa, indicating that DNANP and its organic energetic salts are high energy density materials with good properties.

Abstract:3, 5, 7-Trinitro-1-azaadamantane was synthesized from 1, 3-dinitrobenzene via nitration, reduction, Henry reaction and condensation, the overall yield was 21.5%. The structures of intermediates and target compound were characterized by IR, NMR and melting point apparatus. The effects of molar ratio of HNO₃ to H₂SO₄, mixed acid dosages and charging ways on the nitration reaction were investigated. Intermediate product 1, 3, 5-trihydroxymethyl-1, 3, 5-trinitrocylohexane was synthesized by "stepwise" and "one-pot" process and the reaction time of Henry reaction was shortened by increasing the reaction temperature. The effects of acids and bases on condensation of 1, 3, 5-trihydroxymethyl-1, 3, 5-trinitrocylohexane with ammonia were studied, the reaction conditions and workup procedures were modified. The thermal stability of 3, 5, 7-trinitro-1-azaadamantane was studied by thermogravimetry (TG) and differential scanning calorimetry (DSC). Results show that the optimum process conditions of nitration are determined as: n(HNO₃): n(H₂SO₄)=1: 1.5, m(mixed acid): m(1, 3, -dinitrobenzene)=23 and the charging way is adding 2/3 mixed acid first followed by the other 1/3 after 24 h, with the yield of 70.7%. The time of Henry reaction is shorten by 12 h by increasing the reaction temperature, and the yields of "stepwise" and "one-pot" are 61.8% and 83.5%, respectively. The reaction time of improved condensation is shortened to 3 days, and the simplified workup procedures are filtration, decoloration and recrystallization successively, and both acids and bases reduce the yield of condensation. The decomposition of 3, 5, 7-trinitro-1-azaadamantane starts from about 225 ℃ and the exothermic peak temperature is 331 ℃, which demonstrates that the target compound possesses good thermal stability.

Abstract:To investigate the effect of environmental temperature on the mechanical response and reaction characteristic of reaction material aluminum-polytetrafluoroethylene (Al-PTFE) under the quasi-static compression. Al-PTFE specimens with a size of Φ10 mm×10 mm (the mass ratio of Al and PTFE was 26.5:73.5) were fabricated by cold pressing and sintering process. The quasi-static compression of specimens at different temperatures were conducted by a CMT5105 microcomputer controlled electronic universal testing machine and the stress-strain curves of materials at corresponding temperature were obtained. Results show that the mechanical properties and reaction characteristic of the material are affected by environmental temperature. When the temperature is low (-18, 0, 16 ℃), the material shows a brittleness, and its yield strrength is higher than 28.3 MPa, the failure strain is 1.31-1.49, the specimen is shear failure. With the rise of environmental temperature (22, 35, 80 ℃) the ductility of the material increases, the yield strrength is lower than 20.26 MPa, while the failure strain increases to 1.84-2.08. When the specimen is failed, the increase of deformation capacity makes the energy absorbed by the specimen release instantly along the opening crack formed by tranverse tensile stress, causing the severe reaction of the specimen.

Abstract:To study the mechanical properties of Al/Fe₂O₃/polytetrafluoroethylene(Al/Fe₂O₃/PTFE)material under quasi-static compression and the reaction characteristics under drop-weight impact conditions, Al/Fe₂O₃/PTFE multifunctional structural energetic materials were prepared by adding different volume fractions of PTFE as binder on the basis of Al/Fe₂O₃. Scanning electron microscope (SEM), energy dispersive spectrometer(EDS), and X-ray diffractometer (XRD) were used to characterize the composites. The results show that, under quasi-static compression, the compressive strength, strain hardening modulus, yield strength, density and maximum real strain of the composites increase with the increase of PTFE content. When the volume fraction of PTFE increases from 40% to 80%, the strength of the composites gradually increases from 16 MPa to 87 MPa. Under drop-weight impact conditions, the Al/Fe₂O₃/PTFE composites with 40% and 60% PTFE can both explode and burn severely under the impact of drop weight, while the reactions of composites with 80% PTFE are very weak, only faint slight is observed by high speed photography. With the increase of PTFE, the sensitivities of the composites decrease gradually, and the characteristic drop height is 55, 58 cm and 85 cm respectively. In addition, the ignition time delay was 50, 100 μs and 200 μs respectively.The reaction products of Al/Fe₂O₃/PTFE composites with 40% PTFE after drop-weight impact are AlF₃, Al₂O₃, FeF₂ and C, confirming the occurrence of the thermite reaction. FeF₂ is not the product of the reaction of PTFE with Fe₂O₃, but is produce by the reaction between Fe produced by the thermite reaction and the decomposition products of PTFE.

Abstract:To evaluate the compressibility of modeling powders and determine the pressing process parameters economically and efficiently, a study on the density evolution law of modeling powder during loading was conducted. Firstly, two kinds of TATB based PBX-A and PBX-B modeling powders were taken as the research objects. Based on the normal temperature load-displacement data obtained under the three pressures, their respective pressure-density curves were obtained via transformation. Then, the loading curve equations for the two kinds of modeling powders were constructed by the Kawakita equation and Gerdemann-Jablonski equation used in powder metallurgy, respectively. Finally, the accuracy of the description of the two equations was evaluated, and their suitability for describing the density evolution law in the PBX molding powder pressing process was analyzed. The results show that both the Kawakita equation and the Gerdemann-Jablonski equation can all describe the density evolution cgaracteristics of PBX-A and PBX-B modeling powders in high accuracy. But in contrast, the Gerdemann-Jablonski equation is better than the Kawakita equation, the average relative error of two equations for the PBX-A modeling powder is 1.23% and 1.79% respectively, the average relative error of two equations for the PBX-B modeling powder is 0.95% and 1.57% respectively. Since the description accuracy of the Gerdemann-Jablonski equation is higher than that of the Kawakita equation, and the equation parameters can reflect the flow, rearrangement, and deformation characteristics during loading process, the physical meaning is more clear, therefore, it is more worthy of popularization and application.

Abstract:To improve the experimental efficiency of creep behavior research of polymer bonded explosive (PBX) for the further study of the long-term service performance, the adaptability of Chen′s method in the experimental study of PBX creep behavior was investigated and analyzed. The uniaxial compression creep experiments of a TATB-based PBX material under the stress levels of 5.5, 11, 16.5 MPa and 22 MPa were carried out by Chen′s multistep loading method and separate loading method, respectively. Chen′s data processing method is applied to deal with the creep test results of multistep loading, the creep curves under different loading were obtained, and compared with the creep curves obtained by separate loading method. Results show that creep curves obtained by both methods under the stress levels of 5.5 MPa and 11 MPa are coincident, but the ones obtained by Chen′s method are lower than the ones obtained by separate loading method under the stress levels of 16.5 MPa and 22 MPa, which indicates that Chen′s method can be well applied to the creep experimental study of the material under low stress level, and can be applied to the study of long-term service properties further. While under high stress level, obvious creep hardening effect is observed so that creep curves from Chen method are only in accord with the real separate ones at creep deformation stage but discount occurs in the stage of instantaneous elastic deformation.

Abstract:A coaxial binary composite charge was prepared by 3, 4-dinitrofurazanfuroxan (DNTF) based explosives with two kinds of different aluminum content. The charge was composed of aluminum contents of 5% for inner layer and 20% for outer layer, and the detonation wave-shape characteristics of the composite charge were studied by high speed scanning method. A single charge with same size was prepared by DNTF based explosive with aluminum content of 12.5%. The difference of driving performances of the composite charge and single charge with aluminum contents of 12.5% were compared by cylinder test. Results show that the detonation wave-shape of the inner layer charge will produce a convergence effect when the detonation velocity of outer layer charge is higher, meanwhile, the side interference of the outer layer charge is enhanced, making the wave-shape reveal diverging characteristics obviously. The complex wave-shape of the composite charge not only affects the detonation reaction zone width of the inner and outer layer charge, but also makes the specific kinetic energy and pressure of detonation products in the early stage lower than that of the single charge significantly. With the expansion of detonation products, the specific kinetic energy of the composite charge and single charge is gradually clouse and after the relative specific volume of detonation products is up to 2.69, the pressure of detonation products of the composite charge will be significantly larger than that of single charge.

Abstract:To quantitatively determine the critical diameter and critical thickness of commercial explosives, a continuous resistance wire probe used to measure the velocity of detonation wave and shock wave was developed by ourselves. Using powdery ammonium nitrate/fuel oil (ANFO) as the test object, two kinds of charge forms of unconstrained cone-shaped charge and semi-constraint wedge-shaped charge were designed. The change curves in detonation velocity of the powdery ANFO under the two kinds of constrained conditions were measured and obtained by single experiment, then the corresponding critical diameter and critical thickness could be calculated. Results show that the critical size of powdery ANFO raises with the increase of explosive density. The average critical diameter of the explosive with the density of 0.67 g·cm^-3 under unconstrained condition is 17.52 mm, and the critical thickness is 7.06 mm when the bottom steel plate is constrained.

Abstract:Aiming at the problems about high cost, less sample size and low confidence during the reliability test of programming control device for ready-to-fire of terminally guided projectile performed by the dynamic simulation method using gas gun in industry at present, a new test method was put forward based on the test requirements of electrical parameter detection and structural characteristics of the tested objects. That is, the structural modification to the programming control device for ready-to-fire was carried out to realize the manual release of the setback arming device and complete the relevant electrical parameter detection in the laboratory. Reliability tests to 95 Russian-made and homemade programming control devices for ready-to-fire of terminally guided projectile in all were carried out. The electrical pulse signals of meeting the requirements were collected from pulse generators. The factors affecting the test results were analyzed and the solution measures were put forward. Results show that the tightness of manually start hole is an important factor affecting the action reliability of programming control device for ready-to-fire. After the fuze is started, the manually start hole should be reliably sealed by a special wooden plug to prevent the leakage of the flame energy. The experiment proves the feasibility and economy of this method. This method can be extended and applied to the detection of the electrical parameters of the sabot inductor of a gun-launched missile.

Abstract:A new energetic plasticizer 1, 3-diazido-2-azido-propyl acetate (PCPAA) was synthesized via. azide substitution, hydrolysis, esterification etc reaction using ethylchloroacetate as primary substance. Its structure was identified by IR spectrometry, nuclear magnetic resonance spectrometry and elemental analysis. The esterification reaction conditions were optimized. The factors affecting the esterification reaction yield, including 1, 3-diazido-propan-2-ol (DAG)/ 2-azido-acetic acid (AAE) molar ratio, catalyst, and reaction time were investigated. The thermal properties, friction sensitivity and impact sensitivity of PCPAA were measured by DSC and sensitivity tester. Results show that under the determined optimal reaction conditions of esterification reaction: molar ratio of DAG/AAE is 1.4, catalyst is H₂SO₄, reaction time is 9 h, the yield is 71.4% and the purity is 99.1%. For PCPAA, ρ=1.32 g·cm^-3, glass transition temperature as T_g (DSC) < -80 ℃, decomposition peak temperature T_p(DSC)=240.7 ℃, friction sensitivity as 0%, impact sensitivity as 37.2 cm.

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