High Detonation Velocity Research Articles

Constructing Nitrogen-Rich Fused [5,6,5]-Tricyclic Frameworks Through Rearrangement: Heat-Resistant Zwitterionic Salt Energetic Materials.

This study synthesized nitrogen-rich [5,6,5] fused compounds through a novel rearrangement reaction. Owing to its unique zwitterionic salt structure, rearrangement product 4-1 exhibits high thermal stability (Td > 250 °C), low sensitivity (IS > 40 J, FS > 360 N), and acceptable detonation velocities and pressures (νD = 8520 m s-1 and P = 32.53 GPa, respectively), which are better than those of TNT and TATB. These indicate the potential of zwitterionic salts as thermally stable energetic materials and provide new synthesis strategies for constructing fused polycyclic heterocycles through rearrangement.

Effect of explosives charges types on the jet characteristics, penetration performance and fragmentation patterns of shaped charges

Different explosive materials have been studied numerically and experimentally to assess the efficiency of a small diameter shaped charge in terms of produced jet characteristics and penetration depth into RHA steel targets. 26 different explosives have been simulated numerically using Autodyn hydrocode, whereas recommended explosives have been loaded into small diameter shaped charges by pressing technique and tested by static firing against RHA targets in order to validate the numerical calculations. The numerical analysis has presented an intensive global view about the variation of the shaped charge jets as a potential of the loaded explosive charge efficiencies. A successful trial has been performed to measure the shaped charge jet velocity using detonation velocity VOD 812 apparatus, where its measured value was only 3.6% different from the numerical one for HMX-V5 explosive. Besides, TITAN (L3) flash X-ray radiograph has also been implemented to explore the jet profile using the same explosive type and to measure its jet tip velocity, which has only 2.1% different from that estimated numerically. Extensive fragmentation analysis has been presented, which showed increase in both the fragment number and the fragment speed when the used explosive charge is of high detonation velocity. CL-20 explosive exhibited the largest jet tip velocity and its scaled collapse velocity was found to be 140% of TNT explosive. The calculated average fragment speed has been validated and the measured fragment speed has only 2.3% difference when compared to the SPH calculations.

Quasi-CJ rotating detonation with partially premixed methane-oxygen injection: Numerical simulation and experimental validation

The efficiency gain of rotating detonation depends on several loss factors related to the chamber geometry, the injection principle, the propellants and their mass flow rates, and the equivalence ratio. Numerical simulation can help quantify these losses, and this work presents a Large Eddy Simulation (LES) of rotating detonation in an annular chamber and its validation against experiments. The simulation captured the mixing processes, the overall dynamics of the detonation, the deflagration, and the burnt gas expansion. The injection device was numerically designed to ensure partial premixing of the propellants before injection into the chamber. The chamber had a length of 110 mm, an outer diameter of 80 mm, and a radial width of 10 mm. The mixture consisted of gaseous CH4 and O2 with an equivalence ratio of 1.2 and a mass flow rate of 160 g/s. Combustion kinetics was modeled using a skeletal mechanism with 62 reactions and 16 species. The boundary conditions were adiabatic slip walls. The results reproduce well the detonation velocity (within 1% deviation) and the pressure variation behind the wave. The simulated OH* chemiluminescence compares well with experimental high-speed imaging of the outlet and side of the chamber. The simulation results indicate that 65% of the propellant mass is well mixed in front of the wave whereas 15% of the mixture is burned by deflagration. They show that CH4 and O2 do not axially stratify because they have similar injection dynamics between periodic perturbations induced by the rotating detonation. Good propellant mixing and low deflagration losses explain the high experimental detonation velocity, about 90% of DCJ, and a high combustion efficiency of 98%. These agreements between the computational and experimental results indicate that the simulation is capable of capturing the physical scales relevant to RDC operation and producing reliable results for RDC design.

Modular Synthesis of High Performance Energetic Biocidal Bicyclic Compounds Derivated from Iodopyrazoles.

Modular synthesis can combine different functional modules to flexibly regulate comprehensive properties and study the diversity of compounds. This study established a modular bicyclic synthesis strategy of combining polynitro energetic module with iodine-containing biocidal module. Compounds 1-6 with high iodine content (48.72-69.56 %) and high thermal stability (Td: 172-304 °C) were synthesized and exhaustively identified. By modular synthesis, the detonation properties and gas-production of 3-6 improved greatly expanding their biocidal efficacy and maintained the iodine atomic utilization of iodine-containing module. Notably, 4,5-diiodo-3,4',5'-trinitro-1,3'-bipyrazole (5) and 3,5-diiodo-4,4',5'-trinitro-1,3'-bipyrazole (6) exhibit high detonation velocities (D: 5903 m s-1, 5769 m s-1, respectively) and highest gas production of 212.85 L mol-1 and 217.66 L mol-1 after decomposition. This study diversifies polyiodio-nitro compounds, and also inspire the implementation of similar synthesis strategies to provide family-level synthetic solutions to energetic biocidal materials.

Theoretical study on different substituent-modified derivatives of 6-dinitrophenyl-5,6,7,8-tetrahydro-4-imidazo [4,5-e]furazano[3,4-b] pyrazine.

The compounds of the "565" parent ring structure have received much attention from researchers because of their excellent detonation performance. In the present study, 81 derivatives were designed by introducing different substituents based on 6-dinitrophenyl-5,6,7,8-tetrahydro-4-imidazo[4,5-e]furazano[3,4-b] pyrazine (DIOP), which is a compound of the parent ring structure of 565, and the performance of these derivatives, such as the electronic structure, energy gap, heat of formation, and detonation performance, were investigated. Among these energy-containing derivatives, the density ranges from 1.70 to 2.17g/cm3, the detonation velocity ranges from 8.01 to 10.26km/s, and the detonation pressure ranges from 27.99 to 49.88 GPa. Through comprehensive analysis of several properties of DIOP derivatives, it was found that the oxygen balance of derivatives with the -ONO2 group was greater than zero and close to zero, while the oxygen balance of derivatives with other groups was almost all less than zero. Among them, G8 (D = 10.1km/s, P = 47.72 GPa), H8 (D = 10.11km/s, P = 47.92 GPa), and I8 (D = 10.26km/s, P = 49.88 GPa) had higher detonation velocity and pressure among all derivatives, and their impact sensitivity was better than RDX. Therefore, three potential high-energy and less sensitive energy-containing derivatives, G8, H8, and I8, were screened out. The intramolecular interactions of the three derivatives were further analyzed, and it was found that there were intensive van der Waals interactions and significant spatial steric effects within the molecules, which had a positive effect on reducing the shock sensitivity of the compounds. Moreover, the three derivatives have a large degree of stacking, which leads to a high density. All calculations in this paper are performed using Gaussian16 based on density functional theory. Firstly, the structures of the derivatives were optimized at the level of B3LYP-D3/6-311G**, and then single-site energy calculations were carried out at the level of M06-2X-D3/def2-TZVPP, to reveal the effects of single substituents versus multiple substituents and isomerism on the properties of the DIOP-based energetic derivatives. Multiwfn was used to plot the density of states (DOS) of the derivatives and to calculate the molecular surface electrostatic potential at 0.001 e/Bohr3 electron density, 0.25 Bohr lattice spacing surface.

Highly Dense N-N-Bridged Dinitramino Bistriazole-Based 3D Metal-Organic Frameworks with Balanced Outstanding Energetic Performance.

Due to the inherent conflict between energy and safety, the construction of energetic materials or energetic metal-organic frameworks (E-MOFs) with balanced thermal stability, sensitivity, and high detonation performance is challenging for chemists worldwide. In this regard, in recent times self-assembly of energetic ligands (high nitrogen- and oxygen-containing small molecules) with alkali metals were probed as a promising strategy to build high-energy materials with excellent density, insensitivity, stability, and detonation performance. Herein, based on the nitrogen-rich N,N'-([4,4'-bi(1,2,4-triazole)]-3,3'-dial)dinitramide (H2BDNBT) energetic ligand, two new environmentally benign E-MOFs including potassium [K2BDNBT]n (K-MOF) and sodium [Na2BDNBT]n (Na-MOF) have been introduced and characterized by NMR, IR, TGA-DSC, ICP-MS, PXRD, elemental analyses, and SCXRD. Interestingly, Na-MOF and K-MOF demonstrate solvent-free 3D dense frameworks having crystal densities of 2.16 and 2.14 g cm-3, respectively. Both the E-MOFs show high detonation velocity (VOD) of 8557-9724 m/s, detonation pressure (DP) of 30.41-36.97 GPa, positive heat of formation of 122.52-242.25 kJ mol-1, and insensitivity to mechanical stimuli such as impact and friction (IS = 30-40 J, FS > 360 N). Among them, Na-MOF has a detonation velocity (9724 m/s) superior to that of conventional explosives. Additionally, both the E-MOFs are highly heat-resistant, having higher decomposition (319 °C for K-MOF and 293 °C for Na-MOF) than the traditional explosives RDX (210 °C), HMX (279 °C), and CL-20 (221 °C). This stability is ascribed to the extensive structure and strong covalent interactions between BDNBT2- and K(I)/Na(I) ions. To the best of our knowledge, for the first time, we report dinitramino-based E-MOFs as highly stable secondary explosives, and Na-MOF may serve as a promising next-generation high-energy-density material for the replacement of presently used secondary thermally stable energetic materials such as RDX, HNS, HMX, and CL-20.

Thermal decomposition kinetics and compatibility of NH3OHN5

AbstractHydroxylammonium cyclo‐pentazolate (NH3OHN5), as one of the poly‐nitrogen compounds, has a broad prospect in the field of energetic materials, due to its high specific impulse, high detonation velocity, and the pollution‐free products. In this paper, the thermal decomposition behavior of NH3OHN5 was studied by differential scanning calorimetry (DSC) using four heating rates (2, 5, 8, 10 °C min−1). The apparent activation energy (EK,O=114.31 kJ mol−1), the pre‐exponential factor (AK=4.78×1011 s−1) and the critical temperature of the thermal explosion (Tb=108.08 °C) of NH3OHN5 were calculated by Kissinger and Ozawa method under non‐isothermal heating conditions. The compatibility of NH3OHN5 with 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX), 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX), 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaza‐isowurtzitane (CL‐20), ammonium perchlorate (AP), and hydroxy‐terminated polybutadiene (HTPB) were tested and judged based on a standard agreement (STANAG‐4147). The DSC results showed that NH3OHN5/HMX, NH3OHN5/RDX, NH3OHN5/CL‐20, NH3OHN5/AP and NH3OHN5/HTPB had good compatibility.

Synthetic manifestation of trinitro-pyrazolo-2H-1,2,3-triazoles (TNPT) as insensitive energetic materials.

This study showcases the design and development of a facile method for synthesizing trinitro-pyrazolo-triazole (TNPT) and its derivatives. The synthesized compounds are analysed using multinuclear NMR [1H, 13C, and 15N] and HRMS analyses. Furthermore, X-ray diffraction studies confirm the structure of some TNPT derivatives. Notably, compounds 8, 9, 11, and 12 exhibit good thermal stability with a decomposition threshold above 250 °C, and show a high level of insensitivity towards impact and friction [impact sensitivity (IS) is more than 25 J and friction sensitivity (FS) is above 180 N]. Compound 12, in particular, displays excellent performance characteristics [density 1.76 g cc-1 (at 298 K), a high detonation velocity (Dv = 8550 m s-1), and good thermal stability (Td = 280 °C), with high insensitivity towards impact and friction (IS = 35 J; FS = 180 N)]. The Hirshfeld surface analysis study provides further insight into the sensitivity of the TNPT derivatives.

Linear furoxan assemblies incorporating nitrobifuroxan scaffold: En route to new high-performance energetic materials

Energetic materials science is undergoing a global renaissance aiming to reach an ideal combination between reliable synthetic strategies, high performance and acceptable molecular stabilities. In this work, design and synthesis of novel energetic non-hydrogen furoxan assemblies has been successfully realized. Fine tunability of molecular composition in a series of furoxan-based materials was achieved by the variation of a number of heterocyclic rings and employing N-oxide regioisomerism strategy. Using this approach, advanced energetic regioisomeric azo-bridged bifuroxan assemblies 6 and 7 as well as 3,4′-dinitro-3′,4-bifuroxan 8 with the excellent overall performance were synthesized. Calculations of Hirshfeld surfaces and molecular electrostatic potentials were conducted to better understand the relationship between the molecular structure and mechanical sensitivity in the synthesized series of energetic materials. It was found, that the supramolecular aggregation of 3,4′-dinitro-3′,4-bifuroxan 8 molecules in crystal is more anisotropic that is commonly believed to be more favorable pattern for the low sensitive substances. All target materials have high densities (1.88–1.95 g cm−3), acceptable thermal stabilities (up to 165 °C), high enthalpies of formation (1.6–2.4 kJ g−1) and positive oxygen balance to CO (up to + 25%). As a result, these compounds exhibit high detonation velocities (9.1–9.5 km s−1), excellent heats of explosion (6.6–7.2 kJ g−1) and combustion performance (Isp = 269–281 s). Therefore, these furoxan-based advanced energetic materials unveil new opportunities in search of next-generation functional organic materials for various applications.

A Synthetic Strategy for the Preparation of Fused [5,6,5,5]-Tetracyclic Energetic Compounds

This study explores a straightforward synthetic strategy for preparing fused [5,6,5,5]-tetracyclic energetic compounds. Compound 4 has a high thermostability (Td = 307 °C), which is comparable to that of traditional heat-resistant explosive HNS (Td = 318 °C), but a higher detonation velocity (8262 m s-1) than HNS (7612 m s-1). These results indicate that compound 4 deserves further investigation as a potential heat-resistant explosive.

Theoretical study into effects of different substituents on the structure and properties of Keto-RDX compounds

Forty kinds of keto-RDX based derivatives containing different substituents (for instance –NHNH2, -C(NO2)3, –NHNO2, –NO2 and –ONO2) were designed and have been optimized at the B3LYP-D3/6-311G** level. The effects of single and multiple substituents on the properties of these energetic materials were analyzed. The electronic structure, energy gap, heat of formation, detonation performance, thermal stability, thermodynamic parameters and surface electrostatic potential of the compounds were systematically studied. Compared with the traditional energetic compounds HMX (D = 9.10 km s−1, P = 39.0 GPa) and RDX (D = 8.75 km s−1, P = 34.0 GPa), most of the derivatives designed in this paper have higher detonation velocity and detonation pressure. Among them, the largest density, detonation velocity, and detonation pressure are 2.14 g cm−3 (B6), 10.95 km s−1 (D2), and 57.81 GPa (E7), respectively. Combined with surface electrostatic potential analysis, seven keto-RDX based derivatives of C1, C4, C5, E3, E4, E5, and E7 that can be selected as promising high energy density materials were finally picked out.

Mechanistic elucidation of shock response of bis(1,2,4-oxadiazole)bis(methylene) dinitrate (BOM): A ReaxFF molecular dynamics investigation

The use of trinitrotoluene (TNT) in industrial processes or military operations presents a significant threat to both the environment and human health due to its toxicity. Recently, it has been discovered that bis(1,2,4-oxadiazole)bis(methylene) dinitrate (BOM) can be an appropriate substitute of TNT due to its low sensitivity, high detonation velocity, and nearly insignificant impact on the surrounding environment. In this study, we utilize molecular dynamics (MD) simulations with a ReaxFF force field to investigate the thermomechanical and chemical response of BOM to shock loading. We simulate shocks using the Hugoniostat technique and observe shock-induced, volume-expanding exothermic reactions following a short induction time for strong enough insults. We analyze the shock behavior at various pressures to determine the conditions necessary to initiate detonation and evaluate the consequent events of detonation. A transition between unreacted and reacted materials has been observed and several detonation properties, such as detonation pressure and velocity, have been calculated at the Chapman–Jouguet state. We elucidate the reaction initiation pathways by predicting the intermediates and final products of the exothermic reaction. The quantity of intermediates and products has been studied for different applied shock loadings to understand the effect of loadings on chemical reactions. This study illustrates how reactive MD simulations can be used to characterize the physics and chemistry of high-energy materials subjected to shock loading, and we believe that our research can assist to shed light on numerous features of BOM that may establish it as a viable alternative to TNT.

Insensitive High-Energy Density Materials Based on Azazole-Rich Rings: 1,2,4-Triazole N-Oxide Derivatives Containing Isomerized Nitro and Amino Groups.

It is an arduous and meaningful challenge to design and develop new energetic materials with lower sensitivity and higher energy. How to skillfully combine the characteristics of low sensitivity and high energy is the key problem in designing new insensitive high-energy materials. Taking a triazole ring as a framework, a strategy of N-oxide derivatives containing isomerized nitro and amino groups was proposed to answer this question. Based on this strategy, some 1,2,4-triazole N-oxide derivatives (NATNOs) were designed and explored. The electronic structure calculation showed that the stable existence of these triazole derivatives was due to the intramolecular hydrogen bond and other interactions. The impact sensitivity and the dissociation enthalpy of trigger bonds directly indicated that some compounds could exist stably. The crystal densities of all NATNOs were larger than 1.80 g/cm3, which met the requirement of high-energetic materials for crystal density. Some NATNOs (9748 m/s for NATNO, 9841 m/s for NATNO-1, 9818 m/s for NATNO-2, 9906 m/s for NATNO-3, and 9592 m/s for NATNO-4) were potential high detonation velocity energy materials. These study results not only indicate that the NATNOs have relatively stable properties and excellent detonation properties but also prove that the strategy of nitro amino position isomerization coupled with N-oxide is an effective means to develop new energetic materials.

Trinitromethyl Energetic Groups Enhance High Heats of Detonation

The introduction of groups with high enthalpies of formation can effectively improve the detonation performance of the compounds. A series of novel energetic compounds (10-13) with high enthalpies of formation, high density, and high nitrogen-oxygen content were designed and synthesized by combining gem-polynitromethyl, 1,2,4-oxadiazole, furoxan, and azo groups. All the new compounds were thoroughly characterized by IR, NMR, elemental analysis, and differential scanning calorimetry. Compounds 10 and 11 were also further characterized with single-crystal X-ray diffraction. Compound 11 has high density (1.93 g cm-3), high enthalpy of formation (993.5 kJ mol-1), high detonation velocity (9411 m s-1), and high heat of detonation (6889 kJ kg-1) and is a potentially excellent secondary explosive.

Detonation Wave Propagation of Double-Layer Shaped Charge and Its Driving Characteristics to the Liner

The double-layer charge can effectively improve the axial driving ability of explosives, which shows a considerable engineering application prospect in highly efficient damage warheads. Due to the complex wave structure produced by the overpressure detonation of a double-layer charge, a series of dynamic behaviors inside the shaped charge liner will be affected. By comparing the detonation wave shapes of single-layer charge and double-layer shaped charge structure and the jet shaping parameters of a double-layer shaped charge with different structural parameters, the evolution of detonation wave and the state parameters in the wave system are analyzed in this research. The research found that the double-layer charge with high detonation velocity in the outer layer and low detonation velocity in the inner layer can produce continuous overpressure detonation, which makes the overpressure detonation state be applied efficiently. Meanwhile, this study found that the overpressure detonation field formed by the double-layer charge changes the action law of the traditional single charge on the shaped charge liner. The detonation waveform of the entire charge is controlled by different detonation velocities and detonation energies, and a detonation waveform that matched well with the shaped charge liner is obtained. This study solves the matching relationship between the structure of the overpressure detonation wave system and the properties of a double-layer charge, which is of great value for improving the detonation-driving effect of condensed explosives on surrounding media. The double-layer charge can effectively enhance the potential of explosive charge. It is not only widely used in military fields such as improving the armor-breaking power of shaped charge penetrators and improving the muzzle velocity and concentration of fragments of directional warheads, but also can promote the development of industrial fields such as explosive processing.

Exploring high-energy and low-sensitivity energetic compounds based on experiments and DFT studies

DHADAT shows a high nitrogen content, high detonation velocity and low impact sensitivity. Furthermore, DHADAT exhibits a good ductility, resistance to deformation and stiffness.

Tricyclic compounds with 1,4,2,5-dioxadiazine bridged triazoles and pyrazoles as potential energetic materials

In this study, two energetic molecules with 1,4,2,5-dioxadiazine as a bridge were created by adding triazoles and pyrazoles to the oxazine skeleton. The structural characteristics, thermal behavior, and explosive properties of the obtained compounds 3,6-bis(1-nitro-1H-1,2,4-triazol-3-yl)-1,4,2,5-dioxadiazine (4a) and 3,6-bis(1-nitro-1H-pyrazol-3-yl)-1,4,2,5-dioxadiazine (4b) were investigated using experimental and theoretical techniques. To further elucidate the structure-property relationship, this study conducted calculations and analyses of quantum chemistry, such as the Hirshfeld surface analysis, the electrostatic potential (ESP) surface analysis, and the localized orbital locator (LOL) calculation. Compounds 4a and 4b have higher detonation velocities (4a: Dv ​= ​8328 ​m ​s−1; 4b: Dv ​= ​7681 ​m ​s−1) than the conventional explosive 2,4,6-trinitrotoluene (TNT; Dv ​= ​6881 ​m ​s−1) according to an energetic evaluation. Moreover, the thermal properties and sensitivities of 4a (Td ​= ​155 ​°C, IS ​= ​15 ​J, FS ​= ​288 ​N) and 4b (Td ​= ​192 ​°C, IS ​= ​20 ​J, FS ​= ​216 ​N) were greatly improved compared with the previously reported energetic furazan-1,4,2,5-dioxadiazine derivatives N,N'-((1,4,2,5-dioxadiazine-3,6-diyl)bis(1,2,5-oxadiazole-4,3-diyl))dinitramide (i; Td ​= ​106 ​°C, IS ​= ​4.5 ​J, FS ​= ​100 ​N) and 3,6-bis(4-nitro-1,2,5-oxadiazol-3-yl)-1,4,2,5-dioxadiazine (ii; Td ​= ​148 ​°C, IS ​= ​2.2 ​J, FS ​= ​116 ​N). The excellent sensitivities and acceptable detonation velocities of compounds 4a and 4b make them good candidates for potential mechanically low-sensitive explosives. These findings will enrich the further application of nitrogen heterocycle 1,4,2,5-dioxadiazine in the field of energetic materials.

A novel energetic framework with the combination of 5,6-fused triazolo-triazine and nitropyrazole-tetrazole for energy-stability balanced explosive

In recent years, the introduction of fused rings own high density and low sensitivity has promoted the development of energetic materials. However, the development of energetic compounds containing fused and bridged rings by introducing multiple nitrogen heterocycles at different sites of fused rings is still difficult to progress, which seriously limits the emergence of advanced energetic compounds. In this study, a series of energetic materials choosing different nitrogen rich heterocycles at the vacancies of the fused ring, i.e., neutral compound 5, 6 and their ionic derivatives (compounds 7–12) were designed and synthesized. Compounds 5 and 6 were further confirmed by single crystal X-ray diffraction, while the crystal analysis and theoretical calculations were carried out to explore the relationship between crystal structure and physicochemical properties. All of the newly synthesized compounds (5–12) are insensitive to mechanical stimulation (IS > 40 J; FS ≥ 342 N) and they own the high detonation velocity (D: 8322–9075 m/s). Notably, hydrazine salt 11 own the higher detonation velocity (9075 m/s) and powder density (1.83 g/cm3), but exhibits lower sensitivity (IS > 40 J) than the classical energetic compound RDX (8795 m/s, 1.80 g/cm3, 7.5 J). It is obvious that the combination of 5,6-fused triazolo-triazine and nitropyrazole-tetrazole may be a new energetic skeleton for synthesising the heterocyclic compounds with balanced energy-stability.

Correlated RNN Framework to Quickly Generate Molecules with Desired Properties for Energetic Materials in the Low Data Regime.

Motivated by the challenging of deep learning on the low data regime and the urgent demand for intelligent design on highly energetic materials, we explore a correlated deep learning framework, which consists of three recurrent neural networks (RNNs) correlated by the transfer learning strategy, to efficiently generate new energetic molecules with a high detonation velocity in the case of very limited data available. To avoid the dependence on the external big data set, data augmentation by fragment shuffling of 303 energetic compounds is utilized to produce 500,000 molecules to pretrain RNN, through which the model can learn sufficient structure knowledge. Then the pretrained RNN is fine-tuned by focusing on the 303 energetic compounds to generate 7153 molecules similar to the energetic compounds. In order to more reliably screen the molecules with a high detonation velocity, the SMILE enumeration augmentation coupled with the pretrained knowledge is utilized to build an RNN-based prediction model, through which R2 is boosted from 0.4446 to 0.9572. The comparable performance with the transfer learning strategy based on an existing big database (ChEMBL) to produce the energetic molecules and drug-like ones further supports the effectiveness and generality of our strategy in the low data regime. High-precision quantum mechanics calculations further confirm that 35 new molecules present a higher detonation velocity and lower synthetic accessibility than the classic explosive RDX, along with good thermal stability. In particular, three new molecules are comparable to caged CL-20 in the detonation velocity. All the source codes and the data set are freely available at https://github.com/wangchenghuidream/RNNMGM.

Detonation Reaction Zone and Acceleration Ability of a TKX‐50 Based Polymer Bonded Explosive

AbstractPrevious studies on detonation of the Dihydroxylammonium 5,5′‐bistetrazole‐1,1′‐diolate (TKX‐50), an attractive energetic ionic salt (EIS), were mainly based on thermodynamic codes or small‐scale tests, the available experimental data are not adequate to fully understand detonation characteristics of this new kind of energetic material. This article gives an experimental investigation on detonation reaction zone (DRZ) and acceleration ability of a TKX‐50 based Polymer Bonded eXplosive (PBX), PBX‐TKX‐50. The detonation properties of two traditional explosives: (i)PBX‐HMX, an HMX‐based PBX, (ii) PBX‐RDX, an RDX‐based PBX, both of which contain the energetic compounds and binder in the same mass ratio as PBX‐TKX‐50, are also measured for a comparative analysis. The results show that PBX‐TKX‐50 has the highest detonation velocity and detonation pressure, nevertheless the slowest reaction rate within detonation reaction zone, the longest reaction time and DRZ length among the three PBX samples. Despite its prominent detonation velocity and detonation pressure, the acceleration ability of PBX‐TKX‐50 is lower than PBX‐RDX. The Jones‐Wilkins‐Lee (JWL) equation of state for detonation products calibrated by the cylinder expansion test has severely overestimated the axial acceleration ability of PBX‐TKX‐50 in the numerical simulation of Disc Acceleration eXperiment (DAX), which may due to the fact that remarkable confinement effect and/or geometry effect exist in detonation of the EIS based sample. The mechanisms behind these detonation behaviors are still under investigation in our ongoing studies.