Abstract:In order to accurately understand the mechanical characteristic of 1，3，5-triamino-2，4，6-trinitrobenzene （TATB）-based polymer bonded explosive （PBX） under compressive loading， an in-situ measurement technique based on micro X-ray computed tomography （μ-CT） imaging and digital volume correlation （DVC） was proposed. The in-situ scanning for TATB based PBX sample under uniaxial compression was carried out by using μ-CT and the three-dimensional digital volume images of the samples under different loading were obtained. Then， two sets of digital volume images obtained before and after loading respectively were analyzed by using local DVC method based on the Inverse Compositional Gauss-Newton （IC-GN） algorithm and the three-dimensional internal displacement and strain fields with sub-voxel accuracy were obtained. The internal stress fields were finally rebuilt according to the elastic Hook’s rule. The results show that the generation and development process of the strain localization zone inside the sample could be directly revealed based on the internal measurement technique combining DVC and μ-CT. In addition， the Zero-mean Normalized Cross-Correlation （ZNCC） coefficients are commonly lower at the microcracks. In practical applications， the location of sub-voxel microcracks could be identified by the distribution of ZNCC coefficients.

Abstract:In order to study the law of crack initiation， growth and evolution of explosives under weak load. The numerical simulation of crack initiation and evolution of explosives was carried out by using the material model considering the phenomena of tensile and compressive anisotropy with strain rate effect. The numerical results are in good agreement with the test data， and the applicability of the numerical model is verified. The typical characteristic images of crack generation and evolution of explosives were obtained through a series of numerical simulations， and the effects of initial crack size， loading rate and loading position on the crack propagation process of explosives were also analyzed， which can provide reference for the analysis of damage and fracture process as well as the dynamic response of explosives.

Abstract:To study the relationship between shear band and brittle-ductile transition behavior of typical polymer bonded explosives（PBX） under the influence of temperature， the mechanical response of PBX at 323-363 K was tested by using DIC digital image technology， in-depth analysis of shear band evolution law and failure mode. At the same time， the brittle-ductile transition mechanism of PBX under temperature effect was analyzed based on the theoretical model of crack slip. And the critical conditions of wing crack development and plastic slip area were obtained by considering the effect of temperature. The results showed that at 323-363 K， the variation of the shear band width of the PBX depended on the competition mechanism of dilation and shrinkage. There are four main mechanisms： Ⅰ. Dilatation and shrinkage reach equilibrium； Ⅱ. Shrinkage is dominant； Ⅲ. Dilatation is the main controlling factor； Ⅳ. Dilatation dominates intermittently. Combined with the principle of Griffith energy release， it is found that the shear strength， cohesion and fracture toughness of the specimen are the key controlling factors of the brittle-ductile transition. Under the condition， the judging basis of PBX brittle-ductile transition was obtained. When the condition of wing crack instability was met， the macroscopic failure mode tends to split failure； and when the critical condition of the plastic slip area was achieved， the multiple slip zones are connected to each other to form a plastic slip surface， and the macroscopic failure mode was dominated by the ductile fracture of shear crack slip.

Abstract:In order to evaluate the output energy characteristics of the ignition cap， it was proposed to conduct the ignition cap firing test in an open burster container and use a high-speed mid-wave infrared thermal imager to capture the whole process of the ignition cap firing. Since it was difficult to measure the output flame temperature of ignition cap， the drop weight instrument was used to give the corresponding initial firing energy of ignition cap. At the same time， the infrared thermal imager was triggered to collect flame information. The experimental data and infrared images of ignition cap under three test conditions of normal（25 ℃）， heated（50 ℃） and frozen（-49 ℃） temperature were processed. The results show that the output flame maximum temperature can reach up to 1204 ℃， and the flame duration is about 3-4 ms. The whole process of the flame with time can be divided into four stages： firing， diffusion， forming and dissipation， and the temperature in the top and bottom area of flame is much higher than in other areas. Through calculation and software correction， the measurement error of this test is below 6.6%， which can prove the reliability of the method and provide a new way for evaluating the output energy characteristics of ignition cap.

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: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:In order to verify the applicability of time-temperature-stress principle in tensile creep of TATB-based PBX and realize the evaluation calculation of long-term uniaxial tensile creep deformation， the conventional tensile creep experiment under constant stress but different temperatures and multistep tensile creep experiment under constant temperature of a TATB-based PBX were carried out. The tensile creep curves under constant temperature but different stresses were obtained by decomposing the multistep creep curve following Chen"s method. The coupled creep compliance master curves under reference temperature and stress （30 ℃ and 3.0 MPa） and parameters of Willianms-Landel-Ferry equation considering temperature and stress were obtained by translating and assembling the creep compliance curves using dichotomy calculation program based on the time-temperature-stress equivalence of nonlinear viscoelastic materials. The results show that the tensile creep behavior of TATB-based PBX is well described by the time-temperature-stress equivalent principle in the analyzed temperature range from 30 ℃ to 50 ℃ and stress range from 1.0 MPa to 5.5 MPa， which could be used to predict the long-term tensile creep deformation under low temperature and low stress through the short-term tensile creep tests at high temperature and stress.

Abstract:In order to improve the stability of α-AlH₃， acidic and organic solutions were used as modifiers to treat α-AlH₃. Through structural characterization， stability test， and mechanical sensitivity test， the properties of samples before and after the treatment were compared and analyzed. The performance on hydrogen release and the corresponding modification mechanisms were compared， and the modifier with a better stabilizing effect was obtained. The experimental results show that the proposed modification methods are effective and have a negligible effect on the hydrogen release properties of the studied samples. The weight loss associated with hydrogen release observed for the modified α-AlH₃ does not exceed by 1%， and the changes in initial temperature and peak temperature of hydrogen release are less than ±3 ℃， the maximum hydrogen release rate is not affected by more than 20%. Treatment by hydrobromic acid solution exhibited the best effect on enhancing the storage stability of α-AlH₃， and the amount of hydrogen release for the studied samples during the storage was found to decrease from 0.87% to 0.02%. It suggests that the acidic and organic solution treatment can reduce the impurities and defects on the surface of α-AlH₃ sample， and the amorphous alumina or aluminum hydroxide are likely to be formed on the surface of α-AlH₃ after the acidic solution treatment which enhances the stability of α-AlH₃. Compared with organic solutions， the acidic solution treatment shows a better ability to maintain the hydrogen release properties of α-AlH₃， enhance its storage stability， and reduce mechanical sensitivity， which can be used as a promising modifier in practical applications.

Abstract:In order to study the uniaxial tensile mechanical properties of hydroxyl tetrade propellant under wide temperature and confining pressure， the mechanical properties of propellants under different temperatures（-50 ℃， 20 ℃ and 70 ℃）， confining pressures（0.1， 2 MPa and 8 MPa） and tensile rates（100， 1000 mm·min^-1 and 4200 mm·min^-1） experiments were conducted by using a wide-temperature-confining pressure gas test system. The internal microscopic reasons for the development of macroscopic mechanical properties were analyzed by means of scanning electron microscopy （SEM） and micron CT， with the main of revealing the influence mechanism of external load on mechanical properties of high solid content propellants. The results show that the damage of propellant is mainly attribute to“de-wetting” at room temperature and high temperature. At low temperature and atmospheric pressure， the particles suffer the "de-wetting" and ductile fracture. When the confining pressure increasing， it would change to brittle fracture of particles. Nevertheless， the elongation still increases with the increase of confining pressure. Under high confining pressure and different tensile rates， the mechanical properties of the propellant at room temperature and high temperature are similar. Because at this conditions， high temperature weakens the interaction between binder matrix and solid filler， and the “de-wetting” of the propellant are more seriously， but high confining pressure inhibits the “de-wetting” and weakens the influence of temperature. When the time-pressure equivalent superposition principle （TPSP） is used to carry out the fitting analysis of the principal curve of the maximum tensile strength， at low of -50 ℃， the relationship between the time-pressure displacement factor and the corresponding confining pressure does not conform to the standard form， and the superposition principle of TPSP has certain limitations for the use of high solid content propellants.

Abstract:In order to study the effect of Mg（BH₄）₂ on thermal stability of nitramine explosives， the thermal decomposition properties of Mg（BH₄）₂/RDX， Mg（BH₄）₂/HMX and Mg（BH₄）₂/CL-20 were investigated by differential scanning calorimetry （DSC）. Thermal decomposition products of three mixtures were analyzed by Thermogravimetric analysis-Fourier transform infrared spectroscopy coupling technique （TG-FTIR）. Results show that Mg（BH₄）₂ has different effects on the thermal decomposition and apparent activation energy of three kinds of nitramine explosives， in which the heat release of RDX and CL-20 increases by 14.7% and 32.1% respectively， and but that of HMX decreases by 45.8%. The apparent activation energies of RDX decreases by 15.8 kJ·mol^-1， while that of HMX and CL-20 increases by 19.7 kJ·mol^-1 and 11.5 kJ·mol^-1， respectively. The thermal decomposition products of three kinds of nitramine explosives are the same （mainly NO₂ and N₂O） whether there is Mg（BH₄）₂ or not. Mg（BH₄）₂ has little effects on the thermal decomposition products and the contents of HMX and RDX， but caused the apparent water peak of CL-20. The concentration ratio of NO₂ to N₂O decreased by 89.2%， indicating that Mg（BH₄）₂ promotes the thermal decomposition of RDX and CL-20， and inhibits the thermal decomposition of HMX.

Abstract:The development of new combustion catalysts plays a key role in high performance propellants. Herein， the metal-organic complexes Mg（Salen） and Pb（Salen） were synthesized and characterized using X-ray diffraction， fourier transform infrared， and scanning electron microscope. Their catalytic effects on the thermal decomposition of 1，3，5，7-tetranitro-1，3，5，7-tetrazolidine （HMX） were further investigated by differential scanning calorimetry. The results indicate that the thermal decomposition of HMX is evidently enhanced by the introduction of Mg（Salen） and Pb（Salen）. Compared with HMX， the decomposition peak temperatures of HMX/Mg（Salen） and HMX/Pb（Salen） dropped by 3.0 ℃ and 34.0 ℃， and theoretical apparent activation energies decreased by 7.7 kJ·mol^-1 and 34.4 kJ·mol^-1， respectively. The catalytic decomposition mechanisms of Mg（Salen） and Pb（Salen） are also elucidated by exploring the decomposition kinetics and the reaction function models.

Abstract:To prevent the agglomeration of cobalt ferrite （CoFe₂O₄） nanoparticles and improve their catalytic decomposition performance for Octogen （HMX） and HATO （TKX-50）， graphitic carbon nitride （g-C₃N₄） was applied as CoFe₂O₄ nanoparticles dispersant carrier. The in suit preparation of CoFe₂O₄/g-C₃N₄ binary nanocomposites were achieved through solvothermal method. Corresponding composition， structure morphology and catalytic decomposition performance of CoFe₂O₄/g-C₃N₄ were investigated through X-ray powder diffractometer， scanning electron microscopy， fourier transform infrared spectrometer and differential scanning calorimeter. The results showed that the morphology of CoFe₂O₄/g-C₃N₄ composites is uniform and dense， which reduces the thermal decomposition peak temperature of HMX and TKX-50 by 7.0 ℃ and 41.3 ℃， respectively， and the apparent activation energy by 341.1 kJ·mol^-1 and 21.0 kJ·mol^-1， respectively. Moreover， the introduction of g-C₃N₄ increases the heat release amount. The results of residue analysis showed that the catalytic decomposition of HMX was very complete， while TKX-50 presents incomplete catalytic decomposition， and its residua formed micron bulk mixtures with CoFe₂O₄/g-C₃N₄.

Abstract:3，3′-Diamino-4，4′-azofurazan （DAAzF） is one of the main impurities that produced during the synthesis of 3，3′-diamino-4，4′-azoxyfurazan （DAAF）. However， the effect of DAAzF on the thermal performance of DAAF remains unclear in the past. To this end， a doping strategy based on the dissolution-precipitation method was developed to prepare DAAF@DAAzF explosives by uniformly doping 0.5%-10% DAAzF into DAAF， and the effect of DAAzF on the thermal performance of DAAF@DAAzF explosives was investigated by using simultaneous thermogravimetry and differential scanning calorimetry. The doping of DAAzF decreases the melting point of DAAF-based explosives， with the greatest decrease from 246.4 ℃ to 239.3 ℃ occurring at 10% DAAzF content. For the first time， it is found that the eutectic mixture can be formed when the mass ratio of DAAzF/DAAF is 5/95. Further， the presence of DAAzF decreases the activation energies and pre-exponential factors of DAAF-based explosives during the initial decomposition. Therefore， DAAzF as an impurity accelerates the thermal decomposition of DAAF@DAAzF explosives and reduces their thermal stability.

Abstract:To investigate the effect of deuteration on the vibrational properties of chemical bonds of triacetone triperoxide （TATP） and its thermal decomposition behavior， TATP and deuterated triacetone triperoxide （TATP-d₁₈） were prepared by using acetone and acetone-d₆ as raw materials， respectively， with hydrogen peroxide acting as the oxidant source and sulfuric acid as the catalyst. TATP and TATP-d₁₈ were characterized by nuclear magnetic resonance spectroscopy （NMR）， Fourier transform infrared spectroscopy （FTIR） and differential scanning calorimetry （DSC）. The non-isothermal reaction kinetic parameters of TATP and TATP-d₁₈ were calculated with Kissinger， Ozawa， and Friedman methods. The results show that the deuteration of TATP results in an evident red-shift phenomenon， and the ratio of the stretching frequencies of C—H（D） bonds （ν_C—H/ν_C—D） is about 1.36. The apparent activation energy of TATP-d₁₈ （E_K=80.54 kJ·mol^-1， E_O=83.56 kJ·mol^-1， E_F=72.27 kJ mol^-1） is higher than that of TATP （E_K=67.91 kJ·mol^-1， E_O=71.01 kJ·mol^-1， E_F=63.79 kJ·mol^-1）， indicating that TATP-d₁₈ has higher thermal stability. The calculated thermal explosion critical temperatures for TATP （T_b=402.37 K） and TATP-d₁₈ （T_b=423.46 K） also confirm that deuteration improves the thermal stability of TATP-d₁₈. Finally， the calculated thermodynamic parameters for the non-isothermal decomposition processes of TATP and TATP-d₁₈ indicate that TATP and TATP-d₁₈ would not spontaneously undergo thermal explosions.

Abstract:To explore the detailed thermal decomposition properties of the mixture system consists of ammonium perchlorate-based molecular perovskite energetic material （H₂dabco）（NH₄）（ClO₄）₃ （DAP-4， where H₂dabco²⁺ refers to 1，4-diazabicyclo［2.2.2］octane-1，4-dianiumion） and dihydroxylammonium 5，5"-bistetrazole-1，1"-diolate （TKX-50）， the thermal decomposition characteristics and gas products of DAP-4 and DAP-4/TKX-50 mixtures were comparatively analyzed by using differential scanning calorimetry-thermogravimetry/mass spectrometry/fourier infrared spectroscopy； meanwhile， the changes of characteristic groups in the condensed phase of DAP-4 and DAP-4/TKX-50 mixtures with temperature were investigated by in-situ FTIR. Based on the explorations the thermal decomposition mechanism of DAP-4/TKX-50 mixture was proposed. The results showed that after mixing DAP-4 with TKX-50， DAP-4 had little effect on the thermal decomposition of TKX-50， while the heat generated by the thermal decomposition of TKX-50 made the reversible phase transition endothermic peak of DAP-4 disappeared， but hardly affected DAP-4′s thermal decomposition at high temperature. The thermal mass loss of DAP-4/TKX-50 mixture was divided into two stages. The mass loss of the first stage was 43.4% and the mass loss of the second stage was 52.4%， leaving 4.2% of the decomposition residue. The main gas products produced by thermal decomposition of DAP-4 and DAP-4/TKX-50 mixture were NH₃/H₂O/HNCO/HCN/CO/HCl/CO₂ and H₂O/NO/N₂O/HCl/NH₃/N₂/HNCO/HCN/CO/CO₂， respectively. The thermal decomposition mechanism of the DAP-4/TKX-50 mixture was proposed as follows： the reversible transfer of hydrogen ions occurs first in the molecule of TKX-50 to generate hydroxylamine and 1，1"-dihydroxy-5，5"-bitetrazole （BTO）， then hydroxylamine decomposed into small molecular gases at high temperature while the fragments generated by BTO decomposition partially polymerized into coupling products. Finally， the ionic bond of DAP-4 was broken， leading to instantaneous collapse of the cage-like skeleton. The strongly reducing and strongly oxidizing gas components underwent violent redox reactions at high temperatures and release a large amount of heat.

Abstract:（C₆H₁₄N₂）［Na（ClO₄）₃］ is a representative of energetic perovskite compounds. It is necessary to clarify the corresponding thermal decomposition behavior， thermal decomposition mechanism and sensitivity characteristics in order to promote the application in formulations. Thermal decomposition parameters， including heat release amount and decomposition temperatures， were obtained by simultaneous differential scanning calorimetric and thermogravimetric analyses methods. The relevant decomposition mechanism was analyzed by kinetic simulation calculations. The decomposition products and decomposition processes of （C₆H₁₄N₂）［Na（ClO₄）₃］ were explored by DSC/TG-FTIR-MS coupled technique combined with in-situ infrared technology. The parameters of thermal sensitivity， friction sensitivity and impact sensitivity were obtained by national military standard methods. The results show that the heat of decomposition of （C₆H₁₄N₂）［Na（ClO₄）₃］ is 4227 J·g^-1 at the heating rate of 10 ℃·min^-1 and the decomposition temperature reaches 345 ℃， which is higher than that of most active energetic materials， including Hexogen （RDX）， ogen （HMX） and hexanitrohexaazoisowuzane （CL-20）， indicating an outstanding thermal stability. The decomposition products analysis shows that the cubic cage-like skeleton effectively stabilizes the internal organic molecule， resulting in the high thermal stability of （C₆H₁₄N₂）［Na（ClO₄）₃］. In addition， the outgassing amount of （C₆H₁₄N₂）［Na（ClO₄）₃］ heated at 100 ℃ for 48 h is about 0.04 mL·g^-1， and the impact sensitivity and mechanical sensitivity are 32% and 80%， respectively， which are better than RDX and HMX.

Abstract:To promote the stable production and wide application of silver acetylide-silver nitrate （Ag₂C₂·AgNO₃）， the structural morphology and thermal decomposition characteristics were systematically studied by X-ray powder diffractometry， Fourier tranform infrared spectrometer， scanning electron microscopy， differential scanning calorimeter and thermogravimetric-mass-infrar- ed spectrometry techniques. The results indicate that the prepared Ag₂C₂·AgNO₃ sample is in the form of nanospheres with particle sizes ranging from 400 to 500 nm. There is only one exothermal decomposition process of Ag₂C₂·AgNO₃ with a peak temperature of 234.9 ℃， a weight loss of 8.72%， and a heat release of 1449 J·g^-1，at a heating rate of 10 ℃·min^-1. The apparent activation energy and pre-exponential constant of decomposition process are obtained as 108.9 kJ·mol^-1 and10^8.94 s^-1， respectively. Moreover， the gaseous decomposition products of Ag₂C₂·AgNO₃ were NO， NO₂ and CO₂.

Abstract:To determine the purity of 1，3-dichloro-2，4，6-trinitrobenzene （DCTNB） product accurately， a high-performance liquid chromatography （HPLC） real-time （or in-situ）method for the determination of DCTNB and its impurities， 1，5-dichloro-2，4-dinitrobenzene （DCDNB） and 2，3，4-trichloro-1，5-dinitrobenzene （TCDNB） was established.. The effect of different mobile phase system， mobile phase ratio， flow rate and injection volume etc. conditions on the separation of high performance liquid chromatography for DCTNB was discussed. The quantitative analysis method was carried out by an external standard method. Results show that The optimal chromatographic conditions obtained are as follows： hypersil ODS2 chromatographic column （250 mm×4.6 mm， 5 μm）， UV detection wavelength 240 nm， acetonitrile /water with a volume ratio of 55∶45 as mobile phase， flow rate 1.2 mL·min^-1， column temperature 25 ℃， injection volume 10 μL. Under the above chromatographic conditions， the retention times of DCDNB， DCTNB and TCDNB are 9.20， 10.50， and 14.17 min in sequence with good resolution of all peaks（greater than 3.70）. DCDNB， DCTNB and TCDNB show a good linear relationships in the concentration ranges of 5-250， 5-500 and 5-250 mg·L^-1， respectively， and the linear correlation coefficient R² is greater than 0.999. The detection limits of DCDNB， DCTNB and TCDNB are 0.47， 0.68， 0.85 mg·L^-1， the quantification limits are 1.58， 2.28， 2.82 mg·L^-1， respectively， the relative standard deviation of 1.01%-1.27%， and the standard recovery rates are 98.82%-102.13%．

Abstract:To evaluate the aging performance of acrolein-pentaerythritol resins （123 resins）-RDX based casting polymer bonded explosive （PBX）， accelerated aging tests were performed according to MIL-STD-1751. The microstructure and aging mechanism of casting PBX during aging were investigated by in-situ Infrared Spectroscopy （IR）， 3D-Super Depth of Field Digital Microscope and Scanning Electron Microscope （SEM）. After aging 260 days at 65 ℃， the mass and size change rates of the casting PBX columns are both within 0.25%， which is better than the standards （<1%） of U.S. military standard MIL-STD-1751. The results indicate that PBX columns are stabilization at an acceptable level after aging tests. In addition， no obvious variations on both surface and corss-sectional morphology are observed， except for color changes. The interface between RDX particles and the binder is still well bonded， and the cross section is mainly transgranular fracture. The mechanical properties including both compressive strength and tensile strength of 123 resins-based casting PBX increases obviously with the increase of aging time. After aging 60 and 150 days at 65 ℃， the compressive strengths increase by 6.42 MPa and 13.69 MPa with the increasement of 8.46% and 18.05%， respectively. After aging 90 and 180 days at 65 ℃， the tensile strengths increase by 0.78 MPa and 1.13 MPa with the increasement of 6.34% and 9.19%， respectively. The mechanism of the mechanical properties’ increase was studied by in-situ IR method and the post-casting behavior during aging process was considered as the main reason.

Abstract:The phase transition behavior of HMX-based polymer-bonded explosives （PBX） and pure HMX pellet， prepared by compression molding， was studied by variable temperature wide-angle X-ray scattering （WAXS） and differential scanning calorimetry （DSC）. The HMX-based PBX contained polyester polyurethane （HMX-Estane）， fluororubber （HMX-F₂₃₁₄）， as well as nitrocellulose （HMX-F₂₃₁₄-NC）. The initial β→δ phase transition temperatures （T_i）， as determined by WAXS， were found to be 186 ℃ for HMX-Estane（95∶5）， 188 ℃ for HMX pellet， 192 ℃ for HMX-F₂₃₁₄（95∶5）， and 198 ℃ for HMX-F₂₃₁₄-NC（95∶3∶2）. The addition of the small amount of nitrocellulose （2%） to the binder increased the T_i by about 10 ℃， compared with HMX pellet. All samples retained the δ-phase when cooled from the high temperature phase to 100 ℃ and kept in vacuum for 12 h， except HMX-Estane which went through a reversible phase transition and changed β phase completely after kept at 100 ℃ for 3.5 h. Among the three types of binders only Estane promoted the β→δ phase transition and the reversed δ→β transition of HMX. This result was attributed to the dissolution （on heating） and the precipitation （on cooling） of β-HMX at the HMX-Estane interface.

Abstract:Rapid detection of unsymmetrical dimethylhydrazine （UDMH） and its transformation products in water is of great significance for its pollution control. This paper reviewsthe research progress of chromatographic methods （including gas chromatography， high performance liquid chromatography， and ion chromatography） and non-chromatographic methods （including the electrochemical method， spectrophotometry and chemiluminescence） in the detection of UDMH in water. Then， application of chromatography in in the detection of UDMH conversion products in water was briefly introduced. The advantages and disadvantages of different detection methods in the detection concentration range， sample pretreatment and anti-interference ability， etc.，were pointed out. It was suggested that the design of efficient automatic chromatographic pretreatment device and the combination of various separation and detection technologies would be the future development direction to solve the detection problem of UDMH and its transformation products in water.

Abstract:In order to study the thermal decomposition properties of the characteristic groups of 3，4-Dinitrofurazanylfuroxan （DNTF）， differential scanning calorimetry （DSC） and fast scanning Fourier transform infrared spectroscopy （FTIR）were adopted to study the thermal decomposition properties of DNTF in condensed phase. The changes of characteristic groups of DNTF were studied by using FTIR technology at three different heating rates of 2.5， 5.0， 10 ℃·min^-1. The thermal decomposition kinetic parameters of C─NO₂， furazan ring， and furoxan ring of DNTF were calculated by the Coats-Redfern method. The thermal decomposition mechanism of DNTF was inferred based on the thermal decomposition properties of the characteristic group of DNTF. The results show that the thermal decomposition of DNTF is controlled by the three-dimensional diffusion mechanism. The reactivity of groups in DNTF molecule is nitro>furoxan ring>furazan ring. With the increase of heating rate， the reactivity of each group shows an increasing trend. It is speculated that the thermal decomposition process is that C─NO₂ breaks first， and then the C─C bond connecting furuzan and furoxan ring breaks， and finally the N─O bond in furazan ring and furoxan ring breaks. The furoxan ring decomposes faster than furazan ring.

Abstract:ReaxFF molecular dynamics （ReaxFF MD） simulations were adopted to identify the main intermediate products， final products and chemical reactions during 3，4-dinitro-1H-pyrazole （DNP） thermal decomposition. Accelerating rate calorimeter （ARC）-mass spectrometer （MS） technique was adopted to study DNP thermal decomposition properties and identify the gaseous products. The simulated results illustrate that C₃HO₄N₄， C₃HO₃N₄， C₃HO₂N₃， C₃HNO₂， NO₂ are the main intermediate products， and H₂O， CO₂， N₂ are the main final products. MS detected main gaseous products are H₂O， CO₂， N₂ as well. According to the simulation results， the produced time and abundance of the products are obtained as well. Among which C₃HO₃N₄ is the first generated intermediate product， and H₂O is the first generated final product. C₃HO₃N₄ and N₂ are the intermediate and final products with the largest amount， respectively. Additionally， the main chemical reactions in DNP thermal decomposition process are also acquired by molecular dynamics simulations. According to the generation time and abundance of products， the decomposition path of DNP was obtained.

Abstract:In order to explore the thermal decomposition behavior of 3，5-dimethyl-4-hydroxyphenylpentazole， UV-visible light absorption spectrum combined with quantum chemical calculation was adopted. The thermal decomposition of 3，5-dimethyl-4-hydroxyphenylpentazole （HMPP） with increasing temperature was tracked. The thermal stability of HMPP was tested by differential scanning calorimeter. The results show that the initial decomposition temperature of HMPP is -14 ℃， and the characteristic absorption peak produced by the pentazole ring is at 284 nm in the UV-visible region. The characteristic absorption peak of 3，5-dimethyl-4-hydroxyphenyl azide （HMPA） is 258 nm. With the increase of temperature， the absorption peak of the whole system decreases gradually at 284 nm. In order to explore the specific reasons for the change of HMPP ultraviolet-visible light absorption spectrum， the decomposition products of HMPP were separated by column chromatography. The main decomposition products of HMPP were 2，6-dimethyl-p-benzoquinone and 4-（4-hydroxy-3，5-dimethylphenyl） amino）-2，6-dimethylcyclohexa-2，5-diene-1-one. After the thermal decomposition of HMPP， the uV-visible absorption of the whole system was determined to be caused by the superposition of uV-visible absorption of compounds 4 and 5.

Abstract:To investigate the thermal hazards of the synthetic reaction process of FOX-7， the heat flow curve of the hydrolysisinvolved therein has been measured by using Reaction Calorimeter （RC1）. The n^th-order kinetic models were applied to different temperature systems and the apparent kinetic parameters of these processes were obtained. The results indicated that the exothermic heat of the synthesis reaction was -46.563 kJ∙mol^-1， and the adiabatic temperature rise was 9.1 K. Under the thermal runaway chemical reaction condition， the maximum temperature of the synthesis reaction （MTSR） is 29.1 ℃. The reaction order is 1.21 for synthesis of 2-（dinitromethylene）-5，5-dinitrodihydropyrimidine-4，6-dione. The activation energy （E_a） of the reaction is 73.2 kJ∙mol^-1， with the pre-exponential factor of 5.03×10⁹ s^-1.