Abstract:1-（Trinitromethyl）-3-nitro-5-azidopyrazole （compound 1） was synthesized from 1-acetonyl-3，5-dinitropyrazole via nitration. The 1-（dinitromethyl）-3-nitro-5-azidopyrazole potassium salt （compound 2） was further prepared through a salification reaction with KI. The structures of both two compounds were characterized by Fourier-transform infrared spectroscopy （FT-IR）， nuclear magnetic resonance （NMR）， and single crystal X-ray diffraction. The results show that compound 2 contains both azido and dinitromethylene groups， exhibiting superior overall properties of high decomposition temperature （151.41 ℃） and detonation velocity （8369 m∙s^-1）. The relatively high sensitivity towards external mechanical stimuli make it suitable to be a primary explosive. The detonation performance of compound 2 was further analyzed using Gaussian and Explo5 software. This research provides valuable insights for the design of novel green explosives.

Abstract:In order to reduce the mechanical sensitivity of hexanitrohexaazaisowurtzitane（CL-20）， the co-crystal explosives CL-20/3-MNP （co-crystal 1） and CL-20/4-MNP （cocrystal 2） were prepared by cocrystal technology by combining the isomeric molecules of CL-20 and methyl-nitropyrazole（MNP）：1-methyl-3-nitropyrazole（3-MNP） and 1-methyl-4-nitropyrazole （4-MNP）. The structure of the single crystal was determined by single crystal X-ray diffractometer （SXRD）， and the thermal properties and impact sensitivity of the cocrystal were measured by differential scanning calorimetry （DSC） and BAM drop weight impact sensitivity instrument， and the detonation performance was predicted by EXPLO5. The results show that cocrystal 1 is a triclinic crystal system with a P space group. Cocrystal 2 is an orthorhombic crystal system with a Pbca space group. The melting points of cocrystal 1 and cocrystal 2 are 113.2 ℃ and 147.2 ℃， respectively， which are 25.2 ℃ and 53.7 ℃ higher than those of 3-MNP and 4-MNP， respectively， and the decomposition temperature is higher than that of CL-20， which has better thermal stability， and the impact sensitivity of cocrystal 1 and cocrystal 2 is 20 J and 18 J， respectively， which effectively reduces the sensitivity of CL-20 （2.5 J）. The theoretical detonation velocity is 8060 m·s^-1 and 8643 m·s^-1， and the theoretical detonation pressure is 26.16 GPa and 32.61 GPa， respectively， which are lower than those of CL-20， and the cocrystal 2 sensitivity and detonation performance are comparable to those of LLM-105（17 J， 8560 m·s^-1， 34.99 GPa）， which is expected to be used as a new high-energy and low-inductance cocrystal explosive.

Abstract:To obtain new energetic materials with high energy， low sensitivity and liable storage， TKX-50/AP composite microspheres were prepared by spray drying method. The effects of different feed rates on the morphology of composite microspheres were investigated， and the optimum process conditions were obtained. The morphology and crystal form of the samples were characterized by scanning electron microscope， X-ray diffractometer and Fourier infrared spectrometer. The thermal decomposition performance， impact sensitivity and hygroscopicity of the microspheres were also studied. Results show that the samples are spherical particles with sphericity of Φ=96.40% and d₅₀=1.33 μm at the feed rate of 3.6 mL·min^-1. The crystal structure is different from that of mechanical mixing of TKX-50 and AP. The thermal decomposition activation energy is 184.43 kJ·mol^-1， the characteristic drop is 50.1 cm， and the hygroscopicity is 37% lower than that of the physical mixing， showing excellent safety performance.

Abstract:Ammonium dinitramide （ADN）， as a high-energy green oxidizer， faces significant challenges in engineering applications within solid propellants due to its high surface polarity and strong hygroscopicity. To improve the hygroscopicity of ADN， both emulsion and liquid-phase methods were employed to graft hydrophobic amine compounds， oleylamine and 4-fluorobenzylamine， onto the surface of spherical ADN （PADN）， thereby preparing the modified spherical ADN（PMADN）. The structure and properties of the modified ADN were characterized using scanning electron microscopy-energy dispersive spectroscopy （SEM-EDS）， thermogravimetric-differential thermal analysis （TG-DTA）， and X-ray photoelectron spectroscopy （XPS）. Additionally， hygroscopicity studies were conducted using the desiccator equilibrium method. The results confirmed both amine compounds were grafted successfully and the spherical morphology of the modified ADN was intact. The thermal decomposition temperature of the modified ADN increased from 196.3 ℃ （raw ADN） to 198.3 ℃ and 200.7 ℃， and the impact sensitivity improved from 17.95 J to 24.35 J and 28.80 J （average value）， respectively. After 144 h under 25 ℃ and 57% relative humidity， the moisture rates of the two modified spherical ADN were 1.37% and 1.07%， decreasing 74.95% and 80.44% compared to that of the raw ADN. Additionally， no caking or liquid water was observed on the surface， indicating the modified ADN had excellent anti-hygroscopic properties.

Abstract:To improve the accuracy and objectivity of explosives’ impact sensitivity testing， machine learning methods were applied in the intelligent recognition of explosives’ impact response acoustic signals. Experiments on mixed explosives were conducted using a drop-weight impact sensitivity test device， with an audio acquisition system synchronously capturing acoustic signals during the impact process. One-dimensional time domain and frequency domain features， such as maximum value and bandwidth， were extracted. Short-Time Fourier Transform （STFT） was employed to convert audio data into frequency spectrograms. Data augmentation for one-dimensional data was performed using a Conditional Generative Adversarial Network（cGAN）， while a Deep Convolutional Generative Adversarial Network（DCGAN） was applied to enhance spectrogram data. Multiple machine learning models were employed for explosion classification， including Random Forest （RF）， eXtreme Gradient Boosting （XGBoost）， Back-propagation Neural Network （BPNN）， Support Vector Machine （SVM）， k-means clustering， Convolutional Neural Network （CNN）， and Vision Transformer （ViT）. Results demonstrate that RF， XGBoost， BPNN， and SVM achieve accuracy rates exceeding 99.5% on the real dataset and achieve 100% on the cGAN-augmented dataset. In contrast， k-means clustering initially reaches an accuracy of 98.5% on the real dataset， but accuracy shows a trend of increase followed by decline on augmented data. CNN and ViT achieve accuracies of 98.1% and 98.4% on the real dataset， respectively， and improved to 98.4% and 98.9% on augmented data. However， their performance remaine slightly lower than traditional models due to the constraints of small sample sizes and minor overfitting issues. The proposed deep learning-based intelligent recognition method for explosives’ impact sensitivity in this study achieved a high level of accuracy， demonstrating its reliability and practicality in the task of detecting explosive sound signals. At the same time， it effectively mitigates the subjectivity and inefficiency associated with traditional manual recognition methods， providing a reliable technical solution for the safety use of explosives.

Abstract:For the fast and easy detection of hydrazoic acid gas， an electrosensor for in-situ detection of hydrazoic acid was prepared based on the principle of electrochemical analysis using a screen-printed electrode as a substrate and modified with carboxylated multi-walled carbon nanotubes. The electrochemical detection of hydrazoic acid was constructed by optimizing the solvent of the modification solution， the pH value of the detection solution， and the scan rate. The morphology and performance were characterized. The results show that the in-situ detection electrosensor for hydrazoic acid was prepared as a microelectrode with carboxylated multi-walled carbon nanotubes/glacial acetic acid modification solution， and its response current is about 121% higher than that of the unmodified electrode. The detection sensitivity is high at the solution pH 7.5. The square root of the scan rate is linearly related to the oxidation peak current， and the electrochemical oxidation of N₃^- is a diffusion-controlled process with good selectivity， stability， and reproducibility. The detection limit of N₃^- was 10.4 µmol·L^-1 in the concentration range of 5×10^-5-1×10^-3 mol·L^-1 N₃^- using the differential pulse voltammetry method. The prediction equations for the concentration of HN₃ gas produced by different NaN₃ feedstock contents at different times were derived from the online detection of the actual synthesis of HN₃ gas， and the recoveries of HN₃ are 96.8%-99.5%. In addition， the relationship between the concentration of synthesis HN₃ gas and the response current has been established.

Abstract:The condensation and accumulation of Nitroglycerin （NG）-containing volatiles on various solid surfaces during the propellant rolling process， which pose safety hazards， were investigated using molecular dynamics simulation methods. The study was conducted by constructing a hybrid system model consisting of NG volatiles and solid surfaces， examining the effects of solid surface material， surface roughness， and NG content on molecular dynamics characteristic parameters such as radial distribution function， mean square displacement， diffusion coefficient， and relative density distribution of NG volatiles in the hybrid system. The findings demonstrate that as the mass fraction of NG increases， the size of volatile condensate clusters on the solid surface progressively diminishes. Conversely， the condensation ratio of volatiles exhibits a trend of initial increase followed by a decrease， with the maximum condensation ratio occurring at 70% NG， corresponding to a diffusion coefficient of 0.0364. The diffusion coefficient for the condensation of volatiles containing NG on a silica （SiO₂） surface is 2.1228， which is substantially greater than that on surfaces composed of copper （Cu）， calcium oxide （CaO）， and ferrum （Fe）. However， the uniformity of the SiO₂ surface condensate cluster is poor. The introduction of surface roughness factors has opposite effects on the condensation amount of volatiles on the SiO₂ and Fe surfaces. When the SiO₂ surface goes from smooth to roughness of 0.4 nm， the diffusion coefficient increases from 2.1228 to 10.7156， and the condensation amount of volatiles on the surface increases； however， when the Fe surface goes from smooth to roughness of 0.4 nm， the diffusion coefficient decreases from 17.5673 to 1.8462， and the condensation amount of the surface volatiles decreases.

Abstract:In order to ensure the safe application of solid rocket motors in complex battlefield environments， it is necessary to conduct in-depth research on the response characteristics of NEPE high-energy solid propellants under impact loads. A one-dimensional Lagrange test system was established to measure the pressure wave at different Lagrange location. The unreacted shock adiabatic curve of the measured propellant was obtained through the momentum conservation relationship before and after the shock wavefront， and the JWL EOS of the unreacted NEPE propellant were obtained by using a genetic algorithm. A Φ50 mm NEPE propellant probe-type cylinder test platform was constructed and a 12-channel probe with radial displacement difference was used to record the time of copper cylinder expansion to different probe positions and the time curve of cylinder expansion velocity was obtained. Based on the results of the Φ50 mm cylinder test， the JWL-Miller EOS parameters of the detonation product of NEPE propellant was calibrated by Gurney model and genetic algorithm. Finally， the pressure curves at different Lagrange position were fitted with the ignition and growth model. The results show that the fitting correlation coefficients of JWL EOS parameter curves for unreacted propellant and detonation products are high enough and the obtained ignition and growth model parameters well simulate shock initiation experimental results and the obtained parameters can provide reference for the safety evaluation of solid rocket motors.

Abstract:In order to achieve the inhibition of hydrogen release from aluminum trihydride （AlH₃）， the hydroxyl polybutadiene （HTPB） was chosen as hydrogen absorber to undergo the hydrogenation reaction with unsaturated C═C double bonds under the catalytic action of CA catalyst， eliminating the hydrogen released by the decomposition of AlH₃ in time. The catalytic absorption characteristics of hydrogen released by AlH₃ under HTPB-CA system were studied by micron three-dimensional image microscopy （micron CT）， elemental analysis， thermogravimetry-differential thermal analysis （TG-DTA）， scanning electron microscopy （SEM）， X-ray diffraction （XRD） and other characterization methods. And the effect of hydrogen absorption on the decomposition of AlH₃ was further analyzed. It indicates that CA could catalyze the absorption of hydrogen released from AlH₃ in the HTPB system， inhibiting the generation of voids in AlH₃/HTPB grain which significantly prolongs its volume cracking time. The addition of CA extends the induction period AlH₃ decomposition in the AlH₃/HTPB at 70 ℃ from 6 days to 15 days. And the H content of AlH₃ of the AlH₃/HTPB/CA mixture is 8.94% after 203 days of aging at 60 ℃， while that H content of AlH₃ of the AlH₃/HTPB mixture is only 3.12%. It suggests the inhibition of the decomposition of AlH₃ after the hydrogen reacting with C═C double bond of HTPB to form C─H bond under the catalytic action of CA， demonstrating a hydrogen autocatalytic decomposition mechanism of AlH₃.

Abstract:To explore the effects of the degree of polymerization of polyvinyl alcohol （PVA） as a binder， the content of boronic acid （HB） as a crosslinking agent， polyaniline （PANI） and chitosan （CTS） as an additive on the mechanical properties and combustion start-stop performance of hydroxylamine nitrate based electrically controlled solid propellants （HAN-ECSP）， the samples were prepared by the swelling method. The mechanical properties and combustion start-stop performance were studied by tensile test， combustion start-stop performance test， X-ray diffraction （XRD）， Fourier transform infrared attenuated total reflection （FTIR-ATR）， and optical electron microscopy. The findings indicate that there is minimal variation in crystallinity among PVA samples with different degrees of polymerization. But when the polymerization degree of PVA is 2400±50， the ─OH content is relatively high and the mechanical properties are better. The HB content influences the crosslinking density of PVA. PVA₂₄₉₉-20% HB exhibits a relatively low density and uneven surface depressions. PVA₂₄₉₉-18% HB demonstrates superior mechanical properties， boasting a tensile strength of 2.36 MPa and a tensile elongation of 482.92%. However， it is highly corrosive to the copper electrode. Therefore， an initial network is formed by cross-linking 8% HB with PVA. The PANI or CTS is added to form a semi-interpenetrating polymer network with PVA. The tensile strength of the PVA₂₄₉₉-8% HB-2% PANI propellant is 1.03 MPa， and its elongation at break is 432.85%. The tensile strength of the PVA₂₄₉₉-8% HB-1% CTS propellant is 0.87 MPa， and its elongation at break is 302.28%. Both PANI and CTS addition to the ECSP can achieve combustion start‐stop， and the maximum burning temperature can reach 800 ℃.

Abstract:Energetic polyether binders， as the backbone and matrix of propellants， are the basis to improve the energy levels， mechanical properties， and processing properties of propellants. However， the polar energetic groups in polyethers hinder the movement of molecular chains and reduce the flexibility of polymer chains， leading to a decrease in mechanical properties and restricting the development of energetic solid propellants. Copolymerization modification of energetic polyethers and introduction of flexible structural units to improve flexibility are effective methods to obtain polyethers with diverse structures and adjustable properties. This paper summarizes different types of flexible chain segments introduced into energetic polyethers in recent years， and discusses from the perspectives of main-chain flexible chain segments and side-chain flexible chain segments to explain their effects on the mechanical properties and processing performance of energetic polyether binders. Future design of the flexible chain structure of energetic polyether binders is also discussed， which will provide a direction for the design and development of new types of energetic binders.