Abstract:Cyclotrimethylenetrinitramine (RDX), Cyclotetramethylenetetranitramine (HMX) and Hexanitrohexaazaisowurtzitane (CL-20) own abundant phase transition behavior and characteristics under high pressure/high-temperature and high-pressure. The phase transition routes of three high explosives under different conditions, part of the phase structures under high pressure and p-T phase diagrams were summarized. These researches have provided effective references for the study of detonation behavior and theoretical analysis of energetic materials. Based on current works, there still exist some problems in this area. For example, some divergences still exist about the study of the complex phase transitions, most of the new structures under high pressure are not confirmed and the p-T diagrams are incomplete. In addition, the profound theoretical mechanism of the phase transition has not been sufficiently revealed. Therefore, it will serve as a main tendency to explore the mechanism of transformation between different crystal phases and obtain more information of phase structures in the future research.

Abstract:The single crystal of hydrazinium 3，5-dinitroamino-1，2，4-triazole （HDNAT） was cultivated by slow evaporation from solvent of methanol/water， and its crystal structure was determined by X-ray singal-crystal diffractometer. The crystal structure analysis indicates that HDNAT belongs to monoclinic system with space group P2（1）， and the crystal parameters are a = 0.35976（12） nm，b = 0.9348（3） nm，c = 1.1833（4） nm，V = 0.393.9（2） nm³，Z = 2，D_c = 1.91 g·cm^-3，μ = 0.170 mm^-1，F（000）=230. The thermal behavior of HDNAT was studied by TG-DTG. The decomposition peak of HDNAT is 193.17℃ （DSC）， and it decomposes at solid state. The composite modified double-base （CMDB） propellant formulation based on HDNAT was designed and prepared， and its energy characteristics such as explosion， specific volume， density， characteristic velocity， and specific impulse and combustion performances were tested. For HDNAT-based CMDB propellant formulation， the tested explosion is 6042 kJ·kg^-1， specific volume is 638 L·kg^-1， density is 1.767 g·cm^-3， characteristic velocity is 1592.3 m·s^-1. The study of combustion performances of Φ50 mm engine show that it has stable performances at pressure of 15 MPa， the specific impulse is 250.91 s. Compared with RDX-CMDB propellant， the burning rate of HDNAT-based CMDB propellant increases by 18.8%， and the pressure exponent in partial pressure range is above 0.4.

Abstract:Triaminoguanidinium nitrate （TAGN） was obtained via amination of guanidinium nitrate， and its structure and properties were characterized by elemental analysis， fourier transform infrared spectroscopy （FT-IR）， differential scanning calorimetry （DSC） and scanning electron microscope （SEM）. Short block-like TAGN crystal particles were prepared by ultrasound assissted cooling crystallization in water. The influencing factors of crystal modifier， ultrasonic and cooling process for controlling crystal morphology and particle size， were analyzed by SEM and particle size analysis， and results revealed that ultrasound assissted process can lead to uniform crystalline morphology with narrow particle size distribution. The crystal morphology modifier and temperature control program have a significant effect on the particle size， particle size distribution and crystalline morphology of TAGN. Under the action of ultrasonic （750 W， 20 KHz）， two kinds of high-quality TAGN crystals with uniform crystalline morphology， smooth surface without sharp edge angle， high density and narrow particle size distribution were prepared by using suitable cooling process and PVP K30 （0.03%） as the crystal morphology modifier. Compared with present manufactured raw materials，the comprehensive performance of TAGN have been improved， the characteristic explosion percentage of two kinds of TAGN decreases from 20% to 8% and 4% apart， the characteristic drop height increases 5.9 cm and 3.4 cm apart， the density increases from 1.571 g·cm^-3 to 1.586 g·cm^-3 and 1.589 g·cm^-3 apart， the onset melt point increases from 224.8 ℃ to 227.7 ℃ and 228.2 ℃， respectively. Charging with the prepared product will significantly improve the charging process performance and solid content， so as to improve weapon performance.

Abstract:Phonon spectra play an important role in studying the thermodynamic properties of solids and the microscopic process of initiating chemical decomposition reactions， which can help to reveal the microscopic physical mechanism of initial thermal decomposition mechanism， detonation performance and sensitivity. In this work， the density functional theory with dispersion correction was used to calculate the phonon spectra and thermodynamic properties of 2，4，6，8，10，12-hexanitrohexaazaiso-wurtzitane（CL-20）/1，4-dinitroimidazole（1，4-DNI） cocrystal and co-formers. Through analyzing the phonon density of states， the way in which the phonon mode stores and transfers energy was determined， the direction of thermal energy flow was proposed， and the trigger bond and impact sensitivity order were predicted. The results show that the initial bonds of ε-CL-20 and CL-20/1，4-DNI cocrystal are predicted to be N─NO₂ bonds on CL-20 molecules； the initial thermal decomposition of 1，4-DNI may be related to the ring-opening of imidazole. By comparing the phonon density of states of CL-20 and 1，4-DNI molecules in cocrystal and its pure components. It can be found that the thermal stability of both CL-20 and 1，4-DNI molecules were improved in cocrystal， so that the thermal stability of the cocrystal being superior to the co-formers. According to the "doorway" mode phonon number and characteristic vibration frequency Δω_d， the order of the impact sensitivity is predicted of to be ε-CL-20>CL-20/1，4-DNI>1，4-DNI， completely consistent with the experimental measurement results. The thermodynamic parameters of CL-20/1，4-DNI cocrystal and co-formers have been calculated by phonon spectra， at the same temperature， the order is CL-20/1，4-DNI>ε-CL-20>1，4-DNI. In addition， low-frequency phonons contribute the most to heat capacity（C_V）， and the chemical bond breakage caused by energy transfer may undergo a multi-phonon up-pumping process.

Abstract:In order to obtain the thermal cycling properties of octogen（HMX） and triaminotrinitrobenzene（TATB） based polymer bonded explosive （PBX） ， the thermal cycling tests of HMX- and TATB-based PBX were carried out under the condition of -40—75 ℃. P-wave and S-wave velocity of explosive specimens with 3N （N=0，1，2，…，9） cycles were measured by ultrasonic echo method. The dynamic elastic modulus （Young"s modulus， shear modulus） and dynamic Poisson"s ratio were calculated by ultrasonic measurement method. The static elastic modulus was measured directly through the tensile property test， while the ratio of dynamic and static elastic modulus was calculated. Results show that the density of HMX-based PBX decreases and later the decrease rate slows down with the increase of the cycle number during the thermal cycling test. The density of TATB-based PBX decreases first， then the decrease rate slows down， and finally has a slight upward trend. The change trend of P-wave velocity， S-wave velocity and dynamic elastic modulus of HMX- and TATB-based PBX are consistent with the change trend of their density respectively. Their corresponding dynamic Poisson"s ratio is basically unchanged. There is a positive linear relationship between P-wave ， S-wave velocity and its density. The static elastic modulus first decreases and then increases， the dynamic and static elastic modulus first increases and then decreases， where the inflexion point of HMX-based PBX is in its 15st thermal cycle， and that of TATB-based PBX is in its 21st thermal cycle. The results show that the damage quantity of PBX during thermal cycling is closely related to its density change and internal micro damage. All these phenomenon demonstrate that the ultrasonic longitudinal and shear wave velocities can be used to quantitatively evaluate the thermal fatigue damage of PBX in thermal cycling test. The change trend of the dynamic and static elastic modulus of PBX is related to its micro structure evolution including internal micro-cracks and binder flow in micro-pores.

Abstract:In order to study the effect of the crystal microscopic properties of elemental explosives on their macro-mechanical behavior and impact sensitivity of composite explosives， the micro-plastic characterization methods of TNT， RDX and HMX were studied. And the correlation analysis between the micro-plasticity of the explosive crystals and their impact sensitivities of the elemental explosive was carried out. Nano-indentation technology was used to test and calculate the micro-elasticity and micro-plasticity of TNT， RDX and HMX explosive crystals， and a calculation method based on the ratio of plastic energy and indentation energy （η_P） was proposed to quantify the micro-plastic properties of explosive crystals. The results showed that， compared with the micro-plasticity （δ_h） calculated by the indentation depth， the linear correlation coefficient between the micro-plastic properties （η_P） of the explosives crystals obtained in this research and impact sensitivities （P） of explosives in simple powders reached 95.8%， or micro-plastic properties of simple explosives were highly related to their impact sensitivities on the micro-characterization method of plastic properties of explosives crystals proposed in this paper. This research provided a micro- characterizing method for evaluating safety levels of explosives.

Abstract:The dynamic behavior of Al/Ni energetic structural materials under shock compression loading was investigated by mesoscale simulation. The influence of material composition and manufacturing technique on microstructures were analyzed against the scanning electron micrographs （SEMs） of three typical Al/Ni materials. Two types of mesoscale models were established based on the SEMs and the uniform particle morphologies of Al/Ni material， respectively. The shock responses of Al/Ni material， including particle deformation， pressure， temperature， and propagation of shock waves， were analyzed. The results show that， as for Al/Ni powder composites， Ni particles are the main components of the matrix， and the embedded Al particles gradually reunite with its volume fraction increasing. In contrast， Al layers are the main components of the matrix of Al/Ni multi-layered composites， and Ni particles parallelly distributed in the material. The mesoscale model with the uniform particles could not be used to predict the formations of local high pressure and hot spots， since that such processes are related to the heterogeneous microstructure of Al/Ni materials.

Abstract:The calculations of the crystal structures, in-crystal intermolecular interactions, physicochemical properties, crystal stability and detonation performance for 16 reported cocrystal explosives were carried out to explore their effect on crystal stability and detonation performance of cocrystal explosives. We show that the crystal stability of the cocrystal explosives is mainly determined by the hydrogen bonding (HB) amount when the HB strength is less than 21 kJ·mol^-1. When the HB strength is more than 21 kJ·mol^-1, the crystal stability of the cocrystal explosives is mainly determined by the HB strength. Compared to traditional single-component explosives, the reported 16 cocrystals exhibit better nitrogen content and oxygen balance, but their material densities and detonation performance are less competitive. Through the analysis of CL-20 cocrystal explosives, it is theoretically suggested that enhancing HB strength, instead of introducing more hydrogen atoms to increase HB amount, could be useful to improve crystal stability of cocrystal explosives. This strategy can simultaneously meet the requirement of oxygen balance and nitrogen content in resulting satisfactory detonation performance of cocrystal explosives.

Abstract:The microstructure of HMX (Octogen) crystal particles with average sizes of 5 and 20 μm was studied by in situ variable-temperature small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). The WAXS results showed that the initial β→δ phase transition temperature of HMX (5 μm) is 194 ℃, which is 8 ℃ higher than that of the HMX (20 μm). Guinier law modelling analysis of SAXS measurements revealed the presence of defects with gyration radii between 0.6~0.9 nm will occur in HMX when above 150 ℃. The volume ratio of the defects irreversibly increases with temperature. The number of defects in HMX (20 μm) was found to be higher than that of HMX (5 μm). SAXS, WAXS and scanning electron microscopy all indicate that the thermal stability of HMX (5 μm) is better than that of HMX (20 μm). Finally, the mechanism of defects formation and their effect on the structural integrity and sensitivity of HMX were discussed.

Abstract:In order to study the formation mechanism of 2,4,6-trinitrotoluene (TNT)/ 1-nitronaphthalene (NNAP) cocrystal, powder XRD, FTIR and DSC were used to study the TNT / NNAP samples after grinding at 0 s, 10 s, 20 s, 30 s, 40 s, 50 s and 2 mins. The XRD patterns showed that the new diffraction peak, corresponded to (2 -1 1) plane of TNT/NNAP cocrystal, appeared at 2θ=25.8° and gradually increased its intensity. FTIR spectrum illuminated that the C—N—O bending vibration peak (716 cm^-1) of TNT had a blue-shift and became sharp. At the same time, due to π-π stacking, the C—C bending vibration peak (734 cm^-1) of TNT benzene ring exhibited a red-shift. The DSC curves indicated there were three endotherm peaks during the formation of cocrystal. These results showed that cocrystal packed at (2 -1 1)) plane firstly. H-bond and π-π stacking played important roles in the formation of TNT/NNAP cocrystal. TNT and NNAP firstly generated two eutectics, then transferred into TNT/NNAP cocrystal. The melting point of this cocrystal is 65 ℃.

Abstract:In order to study the crystal nucleation process of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), the CrystlScan multi-channel crystallizer was used to measure the crystallization nucleation induction period of LLM-105 in antisolvent system. The influence of supersaturation on the nucleation of LLM-105 was studied by using the induction period measurement method, and the important nucleation parameters were calculated by the classic nucleation theory. The results show that the induction period of anti-solvent crystallization of LLM-105 decreases with increasing supersaturation. When the supersaturation ratio S<2.53, heterogeneous nucleation was mainly observed, the interfacial tension γ value is 6.67717×10^-23 J·m^-2, and the surface entropy factor f value is 1.49; when S>2.53, the homogeneous nucleation was mainly achieved, the interfacial tension γ value is 9.89842×10^-23 J·m^-2 and the surface entropy factor f value is 2.23. The surface entropy factor values were all less than 3, indicating that the growth mode of LLM-105 in ethyl acetate as an anti-solvent crystal is a continuous growth mechanism, the nucleation rate increases as the supersaturation ratio increases, and the critical nucleus radius and the number of critical nucleation decrease as the supersaturation ratio increases.

Abstract:In order to study the effect of formic acid/water mixed solvent on the growth morphology of energetic ionic salt dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50), interaction energy between TKX-50 faces and formic acid/water mixed solvent was calculated using molecular dynamics method. The growth morphology of TKX-50 in formic acid/water mixed solvent with different volume ratios (1/4, 1/3, 1/2, 1/1 and 2/1) was predicted by modified attachment energy model, and the effect of temperature on the crystal morphology of TKX-50 was simulated. The results show that changing the volume ratio of formic acid/water in the mixed solvent can significantly change the crystal morphology of TKX-50. When the volume ratio of formic acid/water is 1/2 and the temperature is 298 K, the crystal morphology of TKX-50 is relatively closer to spherical shape. Radial distribution function analysis shows that hydrogen bonds, van der Waals forces and electrostatic forces exist between the (1 1 0) crystal face of TKX-50 and the mixed solvent molecules.

Abstract:The crystal data of dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50), dihydroxylammonium azotetrazole-1,1′-diolate (ATZO-1), and sodium 5,5′-azotetrazole-5-oxide pentahydrate (ATO-Na) were analyzed and compared. The effects of the introduction of ─N􀰗N─ and ─N􀰗N(O)─ into the structure of bis-tetrazolium molecules was summarized from the micro-level. Results show that the bistetrazole linked from two tetrazolium rings directly has the densest structure among three compounds, the symmetrical and compact structure further make it own the highest crystal density. Based on the Born-Haber cycle and the Hess law, the heat of formation for TKX-50, ATZO-1 and dihydroxylammonium 5,5′-azotetrazole-5-axide (ATO-1) were calculated. According to the Kamlet Jacobs formula (K-J equation), detonation parameters of these three compounds were also obtained. By comparison, it could be found that both the introduction of ─N􀰗N─ and ─N􀰗N(O)─ bonds can increase the enthalpy of formation for compounds to a certain extent. However, due to the apparent density difference in three crystals, TKX-50 still holds the highest detonation value.

Abstract:The crystal morphologies of β-HMX (octahydro-1,3,5,7-tetranitro-1, 3, 5, 7-tetrazocine) in eight pure organic solvents were predicted based on the modified attachment energy (AE) model by using molecular dynamics (MD) method. Results demonstrate that the morphological dominant crystal faces of β-HMX in vacuum are: (0 1 1), (1 1 -1), (0 2 0), (1 0 0) and (1 0 -2), respectively. The (1 0 0) face is the most polar crystal face and has the largest interaction energy with the solvent molecules, which results in a slow growth rate and appears as dominant face in the final crystal morphology. The (1 0 -2) and (0 2 0) faces have the small interaction energies with the solvent molecules, which appear as small areas or even disappear in the final crystal morphology. The order of the aspect ratio of the crystal morphology is: cyclopentanone>cyclohexanone>N, N-dimethylacetamide (DMAC)>pyridine>acetone>triethyl phosphate>propylene carbonate>Dimethyl sulfoxide (DMSO), which indicates that DMSO and propylene carbonate are more favorable for the spheroidization of β-HMX in crystallization experiments. The experimental crystal morphologies of β-HMX in eight pure organic solvents were investigated using a natural cooling recrystallization method. Results show that the predicted morphologies are in good agreement with the experimental results. The attached energy (AE) model is suitable for predicting the crystal morphology of β-HMX, which may serve as a guide in β-HMX recrystallization experiments.

Abstract:Crystal density is an important parameter for predicting the detonation performance of energetic materials (EMs). Many studies have shown that the theoretical calculation methods are able to figure out accurate densities of CHNO contained EMs. In this work, we overview and categorize some reliable crystal density calculation methods, including isosurface of electron density method, group addition method, molecular surface electrostatic potentials method, crystal packing method and quantitative structure-property relationship method. Among these methods, the effectiveness of molecular volume-based methods depends on its capability to estimate inter- and intramolecular interactions. It is challenging to accurately describe the hydrogen bonding and van der Waals interactions. Due to the huge structure group spaces and highly complex potential energy surface, the crystal packing methods based on empirical forcefields are computationally expensive and lacking accuracy usually. The group addition approach cannot distinguish conformers and polymorphs, and may be unreliable for novel or special energetic materials, which are absent from accurate empirical parameters. The disadvantage of quantitative structure-property relationship method is that it is difficult to give the physical meaning of the equation. The bottleneck of insufficient experimental data and poor model accuracy needs to be solved. Nevertheless, numerous artificial intelligence methods, such as artificial neural networks, genetic algorithm, multiple linear regression, machine learning, have made great achievements in the relationship between properties and structure, facilitating the development of energetic materials based on the materials genome concept and serving as a main tendency in future.

Abstract:The polymorphic transformation （PT） and control technology of hexanitrohexaazaisowurtzitane （CL‍-20） has been a hot area of research in energetic materials， which is also the key issue must be addressed to promote its application. In order to further understand the PT characteristics and mechanism of ε‍-CL‍-20 with different crystallization characteristics， the PT laws and isothermal PT kinetics of ε‍-CL‍-20 were studied based on in‍-situ X‍-ray powder diffraction （XRD） technology. The effect of surface and internal defects on the ε→γ PT behavior of CL‍-20 was discussed. The isothermal PT kinetics of ε‍-CL‍-20 with different crystallization characteristics was analyzed and the related parameters were calculated. The results show that temperature is the dominant factor affecting the solid‍-solid PT of ε‍-CL‍-20. For the conventional particle ε‍-CL‍-20， with the increase of internal and surface defects in the crystal， the initial temperature of PT decreases and the PT rate increases. Compared with 100 μm CL‍-20， ultrafine （0.5-1 μm） ε‍-CL‍-20 has higher starting temperature of PT， but its PT rate is also faster. The abnormal PT behavior of ultrafine ε‍-CL‍-20 is explained from the two‍-sidedness of crystal defects. When CL‍-20 undergoes ε→γ PT under thermal stimulation， both the surface and internal defects of the crystal have an induction effect on the PT process， and the γ crystal preferentially nucleates at the defects such as vacancies， impurities or dislocations with low nucleation barrier on the ε‍-CL‍-20 crystal， and then gradually grows up at these positions.

Abstract:The polymer bonded explosive （PBX） model containing different coating structures is established based on the peridynamics theory and Voronoi method. The dynamic damage behaviors of PBX under different impact speeds are simulated. The simulation results indicate that double-layer coating structure can better protect HMX crystal compared to single-layer coating structure. For single-layer coating structure， the damage mode is mainly transgranular fracture. By contrast， the damage is dominated by intergranular fracture in the case of double-layer coating structure. Moreover， for double-layer coating structure， the quantitative results on damage ratio of HMX is obtained and the performance of different coating structures is ordered. By analyzing the stress state of HMX， it is found that the coating structure can greatly impact the stress distribution. This study can help better design the coating structures in PBX.

Abstract:Aiming at the problems that the crystallization methods （evaporation， antisolvent and cooling， etc.） of the conventional explosive are difficult to accurately control the uniformity of supersaturation and the low solvent recovery rate， an organic solvent nanofiltration（OSN） membrane crystallization apparatus based on pressure-driven and cross-flow filtration was designed and used to study the membrane crystallization process of 1，3，5，7-tetranitro-1，3，5，7-tetrazacyclooctane（HMX）. The effects of key process parameters （temperature and pressure） on the crystal morphology and particle size were discussed， and the crystal morphology and structure were compared with those of evaporative crystallization. The HMX crystals after recrystallization by both methods were characterized by scanning electron microscopy（SEM），X-ray powder diffractometer（XRD） and thermogravimetric-differential scanning calorimeter（TG-DSC）. The long-term operational stability of the nanofiltration membrane was further investigated， and the solvent recovered by permeation was used to re-crystallize. Results show that by the optimal control of temperature and pressure， the membrane crystallization process can obtain β-phase HMX with narrow particle size distribution （coefficient of variation < 46%）， high crystal density （ρ_avg=1.8997-1.9004 g·cm^-3） and excellent thermal stability. Compared with evaporation crystallization， the supersaturation control in the membrane crystallization process is easier to operate， and the prepared crystal morphology is more uniform. After repeated use， the rejection of HMX molecules in the solvent still remained above 92%， showing a good permeation selectivity stability. The β-phase HMX crystals with an median particle size of 34.92 μm and a coefficient of variation of 37.22% can still be prepared by membrane crystallization using permeation-recovered solvent， indicating that this technology can realize the efficient recovery and reuse of the crystallization solvent.

Abstract:In order to study thermal shock damage characteristics of small-size polymer bonded explosive （PBX） hemispheres， 0-100 ℃ water-bathed thermal shock test was carried out for Φ10 mm TATB based and HNS based PBX hemispheres. 3D morphology and distribution characteristics of the damages in the PBX hemisphere were studied by X-ray micro-computed tomography，and the thermal conduction and thermal stress of the sample during the thermal shock process were simulated and analyzed by using the 2D axisymmetric thermal elastoplastic model. The CT results show that the two kinds of samples both started to crack from hemisphere corner， in which the cracks in TATB based PBX hemisphere propagate in a circumferential direction along the edge， with tortuous shape and characteristics of tearing and brittle fracture； The cracks in HNS based PBX hemispheres basically penetrate along the axial direction， with the morphology of straight and characteristics of brittle fracture. The simulation results show that strong tensile stress is generated in the in the hemisphere of TATB based PBX during temperature. And the tensile stress from hemisphere corner to hemisphere center region successively exceeds tensile strength， resulting in the initiation of the main cracks from the edge of hemisphere and propagated inward. The damage characteristics of the sample is consistent with the stress distribution characteristics and the temperature characteristics of the binder under temperature shock. This study lays a foundation for the analysis of temperature shock damage mechanism of TATB-based and HNS-based PBX.

Abstract:The structural integrity evaluation of the metal-explosive bonding interface is of great importance and engineering value. To realize high sensitivity detection of interfacial debonding defects in the metal-explosive structure， the ultrasonic detection and imaging methods based on multiple pulse-echoes was proposed. The acoustic impedance and reflection characteristics at bonding interface of aluminum， shellac， and RDX were calculated and analyzed. For specimens with different adhesive layer thickness and artificial prefabricated debonding defects， debonding information were extracted from the captured multiple echoes. The influence of adhesive layer with different thickness on the amplitude of multiple echoes was discussed and analyzed. Results show that dramatical amplitude difference exists in the reflected waves between the aluminum-adhesive and the aluminum-water interface. Both the first echo and multiple echoes could effectively distinguish the area with and without adhesive layer. The acoustic attenuation caused by the aluminum-adhesive interface keeps accumulating in high order echoes. As the thickness of the adhesive layer increases， the cumulative effect of the acoustic attenuation difference in the multiple ultrasonic echoes between aluminum-adhesive and aluminum-water interfaces gradually weakens. Experimental results show that the minimum debonding defects with Φ1.5 mm circular and 1 mm wide rectangular shape could be detected using multiple ultrasonic echoes method.

Abstract:To improve the yield and purity of 2，6-dimethyl-4-hydroxyphenylpentazole， the preparation method of 2，6-dimethyl-4-hydroxyphenylpentazole （DMAPH） crystal， the raw material of arylpentazole， was investigated through three steps including nitrification， reduction and salification from 2，6-dimethylphenol （DMP）. The structure， crystal morphology and stability were characterized with infrared spectroscopy （IR）， single crystal X-ray diffraction （SCXRD）， scanning electron microscopy （SEM）， powder X-ray diffraction （PXRD）， differential scanning calorimetry （DSC） and theoretical calculation. The results reveal that the yield of 2，6-dimethyl-4-nitrosophenol is up to 90% in the presence of glacial acetic acid and sodium nitrite. The different shapes of DMAPH crystal including sheet， needle， block and plate morphology can be obtained by changing the solvent， while the temperature only affect the particle size of precipitated crystals. The （400） face is the main crystal face of DMAPH crystal from methanol， while in other solvents it is the （214） face. The DMAPH crystals exhibit good thermal stability with decomposition peak temperature ranging from 220-240 ℃. In contrast to amorphous DMAPH powders， the crystalline DMAPH solids have better stability in air， and are more suitable for long-term storage.

Abstract:In order to decrease the acidity of insensitive explosive 3-nitro-1，2，4-triazol-5-one （NTO）， NTO·（3，5-DATr） energetic ionic salt （Ⅰ） and NTO/IMZ energetic co-crystal （Ⅱ） were prepared by the reactions of NTO with 3，5-diamino-1，2，4-triazole （3，5-DATr） and imidazole（IMZ）. The single crystals were obtained by solvent volatilization， and the crystal structures were measured by single crystal X-ray diffraction. Crystal Ⅰ belongs to monoclinic crystal system， space group P2₁/c， with M_r=229.19，a=3.5687（7） Å，b=17.245（3） Å，c=14.655（3） Å，β=93.79（3）°，V=899.9（3） ų，Z=4，D_c=1.692 g·cm^-3；Crystal Ⅱ belongs to orthorhombic crystal system，space group Pbcn，with M_r=207.17，a=16.9398（16） Å，b=5.6802（5） Å，c=17.9111（19） Å， V=1723.4（3） ų， Z=8， D_c=1.597 g·cm^-3. Differential scanning calorimetry （DSC） and thermal weight loss method （TG） were used to test their thermal decomposition properties， and the results show that both Ⅰ and Ⅱ have good thermal stability. The Gaussian 09 program was used to optimize the molecular structures and calculate their enthalpy of formation. Software EXPLO 5 was used to calculate the detonation velocity and pressure of Ⅰ（D=7662.3 m·s^-1，p=21.0 GPa） and Ⅱ（D=6490.2 m·s^-1，p=14.6 GPa）. The mechanical sensitivity was tested by the BAM method. Results show that both of them are insensitive towards impact and friction （IS > 40 J， FS > 360 N）. The pH value of standard samples were measured by pH meter. The pH values of NTO， Ⅰ， and Ⅱ in 0.01 mol·L^-1 standard solution are 2.92 （22.8 ℃）， 4.10 （22.7 ℃）， and 4.98 （22.8 ℃）， respectively， indicating that the formation of salt and co-crystal significantly decrease the acidity of NTO.

Abstract:A cyclo-pentazolate anion-based energetic cocrystal （NH₃OH⁺N₅^-）₂·NH₃OH⁺Cl^-·H₂O was designed and synthesized by AgN₅ （or NH₃OH⁺N₅^-） and hydroxylamine hydrochloride（NH₃OH⁺Cl^-） as raw materials. The structure of the compound was characterized by X-ray single crystal diffraction， infrared spectroscopy and elemental analysis. The structure belongs to the monoclinic crystal system，the P2₁/n space group， a=3.8390（6）Å， b=14.665（2）Å， c=21.975（3）Å， V=1236.4（3）ų， α=γ=90°， β=92.034（3）°， Z=1， D_c=1.589 g·cm^-3. In addition， the thermal stability of （NH₃OH⁺N₅^-）₂·NH₃OH⁺Cl^-·H₂O was studied using DSC and TG， and the results showed that its initial decomposition temperature was about 95.6 ℃. Its detonation velocity and detonation pressure were calculated by EXPLO5 to be 8260 m·s^-1 and 23.79 GPa. （NH₃OH⁺N₅^-）₂·NH₃OH⁺Cl^-·H₂O has low impact and friction sensitivities （IS>40 J； FS>360 N）， as the cocrystal of hydroxylamine hydrochloride can greatly reduce the mechanical sensitivity of NH₃OH⁺N₅^-.

Abstract:In order to realize the non-destructive measurement when predicting the storage life of nitrate ester plasticized polyether （NEPE） propellant， the high temperature accelerated aging， gas content monitoring and uniaxial tensile mechanical property experiment were carried out on NEPE propellant with 10% constant compression strain . The non-destructive storage life prediction model based on characteristic gas contents was proposed through correlation analysis and remaining life prediction model. The results show that during the storage and aging processes， the total amount of CO gas is the largest， reaching more than 1300 mg at different temperatures. The generating rates of NO and CO are growing slowly in the early aging period， and growing faster in the late period. The generating rate of HCl increases rapidly during the eraly and late aging period and slowly in the middle. Maximum tensile strength σ_m and maximum elongation ε_m increase slightly in the early aging period， the former oscillates slightly and the latter gradually increases in the middle period， and both of them decrease sharply in the late period. The correlation between the contents of CO and the maximum tensile strength is largest and there is a single correlation between them at different temperatures. The maximum correlation value reaches about 0.93-0.95. Four life prediction methods of NEPE propellant are established based on traditional and improved aging life prediction model， tensile strength and CO content. The maximum correlation coefficient and estimation results show that the improved prediction model based on the content of CO gas release is most effective.

Abstract:Explosive TNT is the most important weapon energy source in military activities. It not only has a powerful damaging effect， but also has chemical toxicity. Even a trace amount of TNT will pose a serious threat to the natural environment and human health. Therefore， the development of trace explosive detection technology with high sensitivity， high accuracy and fast response has far-reaching research significance for protecting the ecological environment and maintaining human health. Among many trace detection technologies， biosensing technology has the advantages of good selectivity， simple synthesis， fast response and high sensitivity， and has good application prospects. This paper reviews the research progress of biosensor technology in the detection of trace explosives in recent years， focusing on the advantages and limitations of five types of biosensors： antibody immunity， peptides， aptamers， enzymes and multi-parameter loading. Among them， the sensor prepared based on aptamer has good affinity and specificity for explosive molecules， the detection limit is 1000 times lower than other types of sensors， and has good stability， easy modification and modification， and strong structural expansion ability. Future research will focus on the construction of high-throughput trace explosives sensing systems based on bioreceptor components such as aptamers， combined with neural network algorithms and machine learning to construct biosensors with multiple detection and bionic remote sensing properties.