Abstract:In order to develop a new energetic materials, nitrolysis of 3,5,9,11-tetraacetyl-14-oxo-1,3,5,7,9,11-hexaazapentacyclo［5.5.3. 0^2,6.0^4,10.0^8,12］pentadecane (Ⅰ) was studied in detail. Ⅰ was nitrolyzed selectively to 4-nitratomethyl-2,6,8,12-tetraacetyl- 10-nitro-2,4,6,8,10,12-hexaazaisowurtzitane (Ⅱ) with HNO3/Ac2O. While with mixture of nitric and sulfuric acids as nitration reagent, at 80 ℃ directly or at 15 ℃ 2 h firstly then 80 ℃ Ⅰ was nitrolyzed to CL-20 or 4-nitratomethyl-2,6,8,10,12-pentanitrohezaazaisowurtzitane (Ⅲ) respectively. Ⅱcan also be nitrated to Ⅲ. The structures of two new hexaazaisowurtzitane derivatives(Ⅱand Ⅲ) were confirmed by MS,IR,¹H NMR and ¹³C NMR.

Abstract:The synthesis technique of 2-methyl-6-nitroaniline was studied. In previous method, acetylation and nitration of 2-methylaniline were completed in one pot, but the nitration reaction temperature was difficult to be controled. To improve the method, the acetylation and nitration were detached into two parts. The structure of the product, its by-product and its intermediate were characterized by IR,NMR and MS. The results show that the temperature of nitration process can be controlled easily,and the yield is 59.4% and the purity is up to 99.68%.

Abstract:2,2′,5,5′-tetrachloro-1,1′-azo-1,3,4-triazole (1) was synthesized by reaction of 4-amino-1,2,4-triazole and sodium dichloroisocyanurate (SDCI). Its structure was determined by X-ray single crystal diffraction. It crystallizes in the triclinicspace groupP-1,with a=6.2824(13)A,b=7.7173(15)A,c=10.443(2)A,α =89.16(3)°, β=88.20(3)°, γ=89.10(3)°, V=505.94(18) A³,Z=2,M_r=301.92, D_C =1.982 mg·m ^-3,F(000) =296 and μ (MoKα)=1.152 mm^-1,the final R=0.0498 and wR =0.1139. X-ray analysis reveals that a stronger π interaction of the triazole units with the tetrazene moiety.

Abstract:Using 3,4-diaminofurazan (DAF) as starting materials,and lead tetracetate as oxidation reagent,macrocyclic compound of 3,4: 7,8: 11,12: 15,16-tetrafurazano-1,2,5,6,9,10,13,14-octaazacyclohexadeca-1,3,5,7,9,11,13,15-octaene (TATF) was obtained as intermediate. The 3,4: 7,8: 11,12: 15,16-tetrafurazano-1,2,5,6,9,10,13,14-octaazacyclohexadeca-1,3,5,7,9,11,13,15-octaene-1,5,9,11-tetraoxide (TOATF) was synthesized followed by oxidation reaction using Caro′s acid as oxidation reagent. The total yield is 35.3%. The structure of macrocyclic compounds was identified by NMR,FT-IR,MS and elemental analysis. TOATF was identified to be thermal stable by TG technique. The compatibility of TOATF with RDX and HMX was studied using DSC method,and the result show that TOATF is compatible with RDX.

Abstract:Dinitration of toluene by NO₂/O₂ in autoclave was studied. Effects of reaction conditions on the conversion of toluene,the yield of dinitrotoluene(DNT)and the ratio of 2,4-DNT to 2,6-DNT were investigated. The results show that Hβ presents good catalytic activity and regioselectivity in dinitration of toluene. The optimized temperature,pressure,time (for toluene dinitration) were 40 ℃,1.0 MPa,10 h respectively,and the molar ratio of NO₂ to toluene was 3.5 in the presence of Hβ-CH₃SO₃H. Thus the conversion of toluene is 99.3%,the yield of DNT is 89.4% and the ratio of 2,4-DNT to 2,6-DNT is 33. Hβ is recovered by simple phase separation and has almost same catalytic activity after being reused for 4 times.

Abstract:Bonding agent is functional component to improve mechanical properties of solid propellant. A new bonding agent,3-allyl-5,5-dimethylhydantoin(ADMH) was synthesized by the Gabriel method. The condition of the reaction was n(DMH): n (allylbromine): n (methyl alcohol solvent of KOH)=1: 1: 1,and water was used as solvent. The yield of ADMH is 50% and its purity is 99.97%. Chemical structure of ADMH was identified by TG-DTA,UV,NMR,FT-IR and MS etc. Melting point of ADMH is 65-66 ℃ and its decomposition temperature is 168.3 ℃.

Abstract:Hexahydro-1,3,5-trinitro-1,3,5-triazine/resorcinol-formaldehyde (RDX/RF) aerogel and xerogel were prepared by supercritical fluid drying method and freezing drying method. The structure of RDX/RF composites were characterized by scanning electron microscopy (SEM),BET method,X-ray power diffraction (XRD) and differential scanning calorimetry (DSC). The results show that supercritical fluid drying method can get RDX/RF aerogel of typical nano-pore structures and high surface areas. Freezing drying destroys the framework of gels and leads to the rapid decreasing of surface areas of gels. The mean crystal size of RDX in RDX/RF aerogels is between 34-38 nm,and in RDX/RF xerogels is between 50-100 nm. The thermal decomposition temperature of RDX/RF aerogels decreases by about 14-25 ℃,and of RDX/RF xerogels decreases by about 2-7 ℃.

Abstract:The numerical simulation of the detonation of a high explosive (HE) is difficult for traditional grid based methods due to the mesh distortion. Smoothed particle hydrodynamics (SPH) method,as a Lagrangian particle method,is a best candidate method to solve this kind of problem. Modified SPH method presented by the authors with fully variable smoothing length corrects the variable smoothing length effects of standard SPH method in essence,and improves the simulation precision and stability in the large density gradient problem. 1D TNT slab detonation and 3D TNT shaped charge were simulated with the new method and compared with the standard SPH method and theoretical value. The results show that the new SPH method improves the precision and computes the CJ value more correctly. With the numerical simulation for detonation process of the 3D TNT shaped charge,the properties and the rule of the gaseous detonation products were obtained. The results accord with the explosion theoretical value.

Abstract:The thermodynamic properties for some metal-containing(Cu,Fe,Pb,Cr,Sn,Ge) diatomic molecules were studied by density functional theory (DFT) method at B3LYP/6-311G(d,p) and B3LYP/SDD levels and statistical mechanical method based on Morse potential in 300K-5000K. Results show that the heat capacity and entropy obtained CuO,CuCl,FeO and CrO diatomic molecules are in a good agreement with reference data with the deviation of no more than 0.7(J·K^-1·mol^-1),and the entropy variations for GeX,SnX and PbX (X= S,Se,Te) are less than 0.75% in comparison with the reference data.

Abstract:To overcome the disadvantage of experimental methods,plasticizer diffusion in the bond system of hydroxyl terminated polybutadiene (HTPB) propellant was simulated by the molecular dynamics (MD) method. The molecular models of plasticizer and the bond system were constructed in the software of Materials Studio 4.3. The mixture system performed geometry optimization was simulated under the condensed-phase optimized molecular potentials for atomistic simulation studies (COMPASS) force field. The mean square displaces of plasticizer in the bond system were obtained by statistical average. The plasticizer diffusion was obtained by Einstein equation. The diffusion coefficients (10^-4 cm²·s^-1) of dioctyl sebacate (DOS) are respectively 0.0010,0.0020,0.0025,0.0031,0.0043 at the temperature of 273,298,310,323,348 K; and are respectively 0.0025,0.0020,0.0018,0.0015 at the content of 23%,37.5%,47%,60%. The results show that the diffusion coefficients gradually increase with increasing of environmental temperature and decrease a little with increasing of the DOS content.

Abstract:The surface deformation and elasticity recovery of two polymer bonded explosives (PBXs) coded P1 and P2 and two coats named C1 and C2 during “load-unload-recovery” process were measured by nanoindention technology. The results show that the ability of deformation resistance of the four materials above is P1>P2>C1>C2,however the sequence of elasticity recovery is reverse. There is only tiny difference between C1 and P1,P2,but the difference between C2 and P1,P2 is obvious. That means comparatively C1 matches P1 and P2 better from point view of mechanical property. At the same time,the curves of four materials′ surface deformation and elasticity recovery were fitted based on Boltzmann non-linear function,whose relative coefficients were all over 0.99. These indicate that the function can well describe the relationship between the surface deformation,the elasticity recovery and time.

Abstract:A cook-off model of explosive was established to investigate the characteristics of explosive thermal reaction at different heating rates. The numerical simulation was employed to model the cook-off process for GHL explosive at different heating rates by computational fluid dynamics(CFD) software. The decomposition reaction of explosive was described by Arrhenius-equation. According to T-t curves of cook-off test at heating rate of 1 K·min^-1,the activation energy and frequency factor were confirmed. The calculations were conducted to simulate the cook-off tests for GHL explosive at heating rates of 3.3 K·h^-1,1 K·min^-1,3 K·min^-1 and 10 K·min^-1,respectively. The results show that the external heating rate has much influence on the ignition time and ignition location. The ignition time of explosive decreases and ignition location removes from the interior to the edge of explosive cylinder with increasing of the heating rate. The ignition temperature is slightly affected by the heating rate. The environment temperature at igniting in slow cook-off test is lower than that in fast cook-off test.

Abstract:Steven test for PBX-2 explosive was made by using little blunt warhead,pin shape warhead and plane projectiles of 2.0 kg. The pressure change was measured by manganin pressure gauges and poly vinylidena fluoride(PVDF) piezofilm stress gauge. Ignition process was analyzed by high-speed motion pictures. The reaction overpressure of explosive was obtained by blast pressure gauges. Reaction for explosive was analyzed under different shape warhead impacts in Steven test. The results show that explosive reaction is more intensive because of strong shear band under plane impact in Steven test,and reaction degree for PBX-2 explosive is higher under plane warhead.

Abstract:The thermal behaviors of three NTO-based PBXs and their compatibilities with aluminum,copper and stainless steel were investigated using TG-DSC and vacuum stability test(VST). Results show that: (1) A small amount of gases are produced from the three PBXs,suggesting their good thermal stability. When the PBXs contact with aluminum,copper and stainless steel,the additional amount of gas is less than 3.0 mL·(5 g) ^-1,and the decreasing values of peak temperatures are less than 2.0 ℃,showing their good compatibilities. (2) The peak temperatures of the decomposition of NTO and HMX in PBXs are lower than that of the pure explosives,indicating that the coexisting of these explosive can mutually accelerate their decomposition at high temperature.

Abstract:Surface micro-morphology and roughness are considered as the important indexes of PBX turning surface quality. They affect the interface friction in assembly and transportation processes,and affect the adhesive strength of complicated structural PBX components. Different turning manners,such as dry turning and with cutting fluid,and different technological parameters were employed to make samples,which is a type of HMX based PBX. Observation tests of turning surface were established through 3D video optical microscopy and scanning electron microscopy (SEM). The results show that the turning surface consists of continual spiral barred regions,which include knifepoint-extrusion stripes and non- knifepoint-extrusion stripes. The former are planar,and the micro-cracks and cracked explosive particles can be discovered in the latter stripes. All these phenomena are obvious especially in the manner of turning with cutting fluid. Stylus profiler was used to detect the surface roughness. The results indicate the roughness increases with cutting depth,feed and revolutions of machine spindle. A surface roughness empirical formula was deducted based on experiments,which can forecast practical roughness under different cutting parameters.

Abstract:Ultrafine calcium carbonate particles prepared by micro-latex method were determined by means of X-ray diffraction (XRD) and scan electron microscopy (SEM). HTPB propellants with different kinds of calcium carbonate particles were studied. They included ordinary calcium carbonate,cubic ultrafine calcium carbonate,spherical ultrafine calcium carbonate and spherical ultrafine calcium carbonate treated by emulsifying agent. The results show that shapes of ultrafine calcium carbonate particles include clava,spindle,ellipsoid,bamboo-like,sphere,arborization,coral-like,conglutinate,cube and flake. The crystal forms of ultrafine calcium carbonate particles are calcite and aragonite and particle size is less than 1 μm. The experimental condition affects the shapes of ultrafine calcium carbonate particles. The burning rates of HTPB propellant decrease by 29.6%,39.3%,46.2% and 48.6% at 7 MPa,respectively,when 3% ordinary calcium carbonate,cubic ultrafine calcium carbonate,spherical ultrafine calcium carbonate and spherical ultrafine calcium carbonate treated by emulsifying agent were added to HTPB propellant. Different kinds of calcium carbonate particles may decrease the burning rate of HTPB propellant. The burning rate of HTPB propellant with ultrafine calcium carbonate decreases more than that with ordinary calcium carbonate. Ultrafine calcium carbonate particles treated by different methods affect the burning rate of HTPB propellant little.

Abstract:The study of the effects of nano-carbonate burning rate catalysts on the pressure exponent,heat of explosion and mechanical properties of the AP/Al/HTPB propellants were conducted. The results show that the catalyst can reduce the burning rate pressure exponent of the propellants to 0.20 in the pressure ranges of 4-10 MPa and 10-18 MPa. The combustion efficiency and the heat of explosion of the propellants increase as the increasing of the content of the nano-catalyst. It also shows the nano-catalyst has some effects on the mechanical properties and processing properties of the propellants. It has found that the suitable weight fraction of nano-carbonate catalyst in the propellants is 0.5%-1%.

Abstract:The effects of ammonium perchlorate (AP),hexahydro-1,3,5-trinitro-s-triazine (RDX),aluminum powder (Al) and ammonium dinitramide (ADN) used as solid fillers on energy characteristics of composite PBT (BAMO and tetrahydrofuran (BAMO-THF) copolymers) propellants plasticized with A3 (bis(2,2-dinitropropyl)acetal/bis(2,2-dinitropropyl)formal) and NG/DEGDN (glyceryl trinitrate/diethyleneglycol dinitrate) respectively were investigated using least free energy method. Calculated results indicate that the variation curves of the specific impulse of propellants are characteristics of a parabola with the increasing of RDX content,and there exist optimum content ratios of solid fillers in respective systems. Compared with those plasticized with A3,propellants plasticized with NG/DEGDN show higher specific impulses. The specific impulses are evidently enhanced due to the decreasing in average relative molecular mass of combustion products,caused by the addition of 15% ADN instead of AP into the formulations.

Abstract:The energy parameters of the propellant containing 3,3′-dinitro-4,4′-oxazafurazan(DNOAF) were calculated under standard condition(p_c/p_o=70: 1). Replacing ammonium perchlorate(AP) with DNOAF in HTPB propellant increases the specific impulse for 120 N·s·kg^-1,and NC/NG/DNOAF smokeless CMDB propellant has a specific impulse of 2558 N·s·kg^-1,and replacing HMX with DNOAF in PET/NG/DEGDN/HMX propellant increases the specific impulse for 194 N·s·kg^-1.

Abstract:Curing processes of HTPB/TDI and Al/HTPB/TDI composites were measured by non-isothermal differential heating calorimetry at different scanning rates. Results show that the values of apparent activation energy,reaction order and frequency factor of HTPB/TDI system are 51.826 kJ·mol^-1,0.926,2.412×105 min^-1,respectively. After adding aluminum powder,the peak temperature of the curing process is decreased. The values of apparent activation energy,reaction order and frequency factor are increased to be 76.402 kJ·mol^-1,0.944,2.53×108 min^-1,respectively. The curing reaction mechanism of HTPB/TDI meets Avrami-Erofeev Equation G(α)=［-ln(1-α)］ⁿ. The addition of aluminum powder into HTPB/TDI curing system only makes little change on index n. The curing reaction of HTPB/TDI can be accelerated by aluminum powder for the initial 18% of reaction extent and aluminum powder slows down the curing reaction for the latter 82% of reaction extent.

Abstract:According to the composition and structure properties of the NEPE propellants,the finite element calculation model of the NEPE solid propellants was established by the ANSYS 10.0 finite element calculation software. The damage trend and variation regularity of the NEPE propellants under unilateral tensile was simulated. Effects of the solid particle content,bonding agent content,composition and particle diameter of the oxidant on the damage trend of NEPE propellants were discussed by comparing the stress concentration factor α and the debond angle θ. The results show that the mechanical performance simulated by the established finite element model of the NEPE solid propellants is in good agreement with the experimental regularity.

Abstract:The non-isothermal crystallization behaviors of poly(3,3-bis-azidomethyl oxetane) (PBAMO) were studied during cooling with different constant cooling rates by using differential scanning calorimeter (DSC). Results show that the relationship of peak temperature of crystallization process and cooling rate is expressed well via exponential decay equation,and the crystallinity reaches the maximum value when cooling rate equals 2 ℃·min^-1,while the fastest crystallization rate appears when cooling rate equals 5 ℃·min^-1. Ozawa exponent m obtained by using Ozawa equation increases with temperature increasing and can be divided into three regions: (1) T＜14 ℃,m＜3; (2) T=14-18 ℃,m=3-4.12; (3) T＞18 ℃,m approaches 5. The crystallization activation energy calculated from Kissinger equation is 59.37 kJ·mol^-1.

Abstract:The interactions of double-base component mixture of nitroglycerin and nitrocellulose (NC/NG) with ammonium dinitramide (ADN) were investigated by pressure differential scanning calorimetry (PDSC),thermogravimetry-derivative thermogravimetry (TG-DTG) and vacuum stability test (VST). The results show that the decomposition exothermic peak temperature of NG in the NC/NG is 207.0 ℃,but drops down to 159.8 ℃ in the (NC/NG)/ADN system. The peak temperature drops down further to 153.6 ℃ at high pressure. The decomposition peak temperature of NC/ADN is a drop in 4.8 ℃ by comparison with NG/ADN. The greater part of ADN is not accelerated to promote decomposition by NG. It is shown that the effect of NC to ADN is strongly than NG to ADN. Besides,the compatibility between NC/NG and ADN was evaluated by VST. The increaser volume of gas products for mixed system is more than 11 mL,and is of “excessive” rating. It is proved that a strong interaction of NC/NG with ADN occurs also at 90 ℃.

Abstract:The electrical conductivity of combustion products of composite propellant containing Cs salt which used in magneto-hydro-dynamic (MHD) generator were calculated through Sahe equation and model of electrical conductivity. The basic thermodynamic parameters used in the model of electrical conductivity were calculated by applying thermodynamic equilibrium constant equation. Through theoretical calculation,the change of electrical conductivity along with the Cs salt content and aluminum content was obtained. The results show that for the given aluminum content,the optimal range of Cs salt content(mass percent) is 5%-10%; the higher combustion temperature and lower pressure of combustion chamber promote higher electrical conductivity.

Abstract:The specific heat capacity of carbohydrazide perchloric acid energetic coordination compounds was studied by differential scanning calorimetry (DSC). The specific heat capacity of ［Co(CHZ) ₃］(ClO₄)₂ was mensurated at 50-140 ℃ and the specific heat capacity of ［Mn(CHZ) ₃］(ClO₄)₂,［Zn(CHZ) ₃］(ClO₄)₂ and ［Ni(CHZ) ₃］(ClO₄)₂ was mensurated at 50-200 ℃. The equations of the specific heat capacity changing with the temperature are fitted by the least square method,i.e.R≥0.985,SD≤0.060. The equations of the specific heat capacity of ［Mn(CHZ) ₃］(ClO₄)₂ and ［Zn(CHZ) ₃］(ClO₄)₂ are functions of second degree at 50.1-131.2 ℃ and that of ［Ni(CHZ) ₃］(ClO₄)₂ is the function of four degree at 50.1-142.9 ℃,however that of ［Mn(CHZ) ₃］(ClO₄)₂,［Zn(CHZ) ₃］(ClO₄)₂ and ［Ni(CHZ) ₃］(ClO₄)₂ are functions of three degree at the other temperature,and that of ［Co(CHZ) ₃］(ClO₄)₂ is the function of three degree. ［Co(CHZ) ₃］(ClO₄)₂ and ［Ni(CHZ) ₃］(ClO₄)₂ were analyzed by method of TG and FTIR. TG curves show that only ［Co(CHZ) ₃］(ClO₄)₂ loses weight after 140 ℃. FTIR spetra of two samples heated are different from that of the originals.

Abstract:Aiming at the problems (low efficiency,lacking processing safety,and so on) of traditional dehydration method,the mechanism of pervaporation (PV) technology was analyzed. The types and performances of the membranes and their applications in dehydration of ethanol/water mixtures were retrospected. The development of dehydration of hydrazine fuels by PV was reviewed. The results show that PV can overcome the shortages of traditional dehydration method of hydrazine fuels. According to the particular properties of hydrazine fuels,chitosan,ceramic and zeolite are used for suitable membrane materials for dehydration of hydrazine fuels by PV. Multi-level PV set in series can improve the dehydration efficiency. The key fields about dehydration of hydrazine fuels by PV include: recovery of hydrazine fuels from diluted aqueous solutions; dehydration of high concentration hydrazine fuels; and development of high-performance membrane materials.

Abstract:The tautomerization and decomposition channels of amino-tetrazoles,mainly 5-amino-tetrzole and 1,5-diamino-tetrzole,were reviewed. The up-to-date study shows that 1-substitute-amino-tetrazoles,2-substitute-amino-tetrazole and 1-substitute-imino-tetrazoles are the most common isomers of amino-tetrazoles. There are basically two mechanisms for the decomposition of amino-tetrazoles. In the first mechanism the two bonds of the tetrazole ring break off,resulting in RN ₃ and NH ₂CN. The second decomposition channel comprises two steps. Firstly the N—N bond is cleaved,leading to RN ₃. Then the produced RN3 loses one molecule N ₂. In this paper,the tautomerization mechanisms of amino-tetrazoles represented by 5-amino-tetrazole and 1,5-diamino-tetrazole were investigated by using high level quantum chemistry calculations,the results show that the active energy of the first decomposition path way is lower than that of other paths,so it is the most probable reaction path.

Abstract:Polymer bonded explosives are particulate composites containing elastic particles in a viscoelastic binder. The particles occupy an extremely high fraction of the volume,often greater than 85%. Under low strain rate loading and at about room temperature,the elastic modulus of the particles can be four order of magnitude higher than that of the binder. These two characteristics make effective elastic properties predict more difficultly. As a result,PBXs provide unique challenges for micromechanical modeling. Some micromechanical-based methods for the determination of mechanical properties of PBX were introduced,the advantages/disadvantages and the prospects of these methods were reviewed briefly. Three-dimensional models with damage,using computed tomography images and simulating manufacturing process are suggested to be the key point of future work.

Abstract:An unsymmetrical nitrofurazanyl polynitrobenzene ether was synthesized via Williamson reaction and the structure was confirmed by NMR,FTIR and elemental analysis. Some properties of the compound,such as density,heat of formation,oxygen balance,detonation velocities and detonation pressures were calculated.

Abstract:Reduced-sensitivity CL-20 were prepared by special crystallization technique. Impact sensitivity and crystal properties including particle sizes and distribution,particle shape and internal porosity were compared between normal CL-20 and reduced-sensitivity CL-20. The results show that reduced-sensitivity CL-20 has better crystal quality and lower impact sensitivity.

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