Traditional Explosives Research Articles

Rapid modulation of electrostatic sensitivity and explosive performance by X‐ray radiation

AbstractIt is highly desirable to actively modulate the explosive performance and sensitivity of traditional explosives, such as RDX (hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine), and HMX (cyclotetramethylene tetranitramine), especially to reduce their explosive power and electrostatic sensitivity. Herein, a new avenue is found to effectively modulate the explosive performance and electrostatic sensitivity by direct irradiation of high‐density X‐ray from synchrotron radiation. RDX as a kind of popular and high‐performance explosive, is chosen to demonstrate the modulated effectiveness. After X‐ray irradiation with different irradiation time, the detonation velocity (DV), detonation pressure (DP), heat of detonation (HoD), and electrostatic sensitivity of RDX are determined. Compared with the electrostatic sensitivity and explosive parameters of original high‐quality RDX, the maximum electrostatic sensitivity value is increased to 1061 mJ after irradiation, which is an enhancement ratio of 39.61 %. The lowest DV is 7.57 km/s (−14.27 %), the lowest DP is 16.23 GPa (−53.20 %), and the lowest HoD is 5.15 kJ/g (−9.65 %). These changes mainly originate from the changes in the structure and crystal structure of RDX molecules after irradiation, as evaluated by Scanning Electron Microscope (SEM), X‐ray Diffraction (XRD), and X‐ray Photoelectron Spectroscopy (XPS). The mechanism of RDX modulation by X‐ray is due to denitrification, which always accompanies lots of energy releases, thus impacting the electrostatic sensitivity and explosive power of RDX. Therefore, this study not only provides a new method for reducing electrostatic sensitivity to improve the safety of storage, transportation, and application of RDX, but also holds great potential to reduce explosive performance by non‐contact means.

Searching new cocrystal structures of CL-20 and HMX via evolutionary algorithm and machine learning potential

In this work, we report the discovery of energy cocrystals using an efficient iterative workflow combining an evolutionary algorithm and a machine learning potential (MLP). The compound 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) has attracted significant attention owing to its higher energy density than traditional energetic materials. However, the higher sensitivity has limited its applications. An important way to reduce its sensitivity involves cocrystal engineering with traditional explosives. Many cocrystal structures are expected to be composed of these two components. We developed an efficient iterative workflow to explore the phase space of CL-20 and 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) cocrystals using an evolutionary algorithm and an MLP. The algorithm was based on the Universal Structure Predictor: Evolutionary Xtallography (USPEX) software, and the MLP was the reactive force field with neural networks (ReaxFF-nn ) model. A set of high-density cocrystal structures was produced through this workflow; these structures were further checked via first-principles geometry optimizations. After careful screening, we identified several high-density cocrystal structures with densities of up to 1.937 g/cm3 and HMX: CL-20 ratios of 1:1 and 1:2. The influence of hydrogen bonds on the formation of high-density cocrystals was also discussed, and a roughly linear relationship was found between energy and density.

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.

SPH numerical simulation of SC-CO2 directional fracturing and emulsion explosives for rock breaking

SC-CO2 (Supercritical carbon dioxide) directional fracturing is a promising alternative to explosive blasting in complex environments. This study aims to establish an equivalent method for directional fracturing using traditional explosives, promoting broader adoption of this technology. We conduct a comparative experiment analyzing explosive and SC-CO2 rock breaking, developing the SPH (Smoothed Particle Hydrodynamics) numerical model that includes characteristics of the rock-breaking area and dynamic effects of SC-CO2 and explosives. Additionally, we investigate the influence of the directional fracturing device on the energy release coefficient. Proposing a numerical simulation method for SC-CO2 directional fracturing based on equivalence to No.2 rock emulsion explosive, we use the SPH particle algorithm to enhance visualization of the rock-breaking area. Our findings show that the explosive method yields a larger rock-breaking volume than SC-CO2. Under identical explosive charges, the directional cracker model inhibits explosive energy release, with energy decreasing as distance increases. Calculating an inhibition coefficient of 0.45 for the cracker model in terms of explosive granite, the rock-breaking volume index is 0.48, with an average value of 0.465. In mudstone sites, a similar trend is observed with an average energy release inhibition coefficient of 0.44.

Investigating residue dissolution of insensitive high explosives in two sandy soil types: A predictive modelling approach

The demand for munitions that are less likely to detonate accidentally has led to an increased use of Insensitive High Explosives (IHE), which contain substances like 2,4-dinitroanisole (DNAN) and 5-nitro-1,2,4-triazol-3-one (NTO). These substances have different properties compared to traditional explosives, and their potential environmental impact is not well understood. When these explosives are used in live-fire training exercises, their residues end up in the soil. It is important to determine how these residues dissolve and enter the soil. This study aimed to experimentally measure the rate at which an IHE formulation dissolves when exposed to rainwater with pH levels of 5.0 and 6.5, and to simulate how these residues dissolve and move through two different soil types. The dissolution rates were determined by conducting experiments in which IHE particles (30–60 mg) were exposed to water with varying pH levels and temperatures. The results showed that the dissolution rate of NTO did not vary with pH, while the dissolution rate of DNAN and RDX decreased with decreasing pH. Specifically, the dissolution rate of DNAN decreased from 18 ± 40 μg min−1 at pH 6.5 to 6 ± 4 μg min−1 at pH 5.0, while the dissolution rate of RDX decreased from 8 ± 4 to 3 ± 1 μg min−1. These findings were used to develop a stochastic model that successfully simulated the concentration of IHE in the leachate from soil columns over time. A sensitivity analysis revealed that while dissolution rates determined the amount of mass entering the soil, they did not significantly regulate the amount of mass that migrated through the soil and leached out of the soil columns.

Evaluation of canine training aids containment for homemade explosive and components by headspace analysis and canine testing.

While canines are most commonly trained to detect traditional explosives, such as nitroaromatics and smokeless powders, homemade explosives (HMEs), such as fuel-oxidizer mixtures, are arguably a greater threat. As such, it is imperative that canines are sufficiently trained in the detection of such HMEs. The training aid delivery device (TADD) is a primary containment device that has been used to house HMEs and HME components for canine detection training purposes. This research assesses the odor release from HME components, ammonium nitrate (AN), urea nitrate (UN), and potassium chlorate (PC), housed in TADDs. Canine odor recognition tests (ORTs) were used with analytical data to determine the detectability of TADDs containing AN, UN, or PC. Headspace analysis by gas chromatography/mass spectrometry (GC/MS) with solid-phase microextraction (SPME) or online cryotrapping were used to measure ammonia or chlorine, as well as other unwanted odorants, emanating from bulk AN, UN, and PC in TADDs over 28 weeks. The analytical data showed variation in the amount of ammonia and chlorine over time, with ammonia from AN and UN decreasing slowly over time and the abundance of chlorine from PC TADDs dependent on the frequency of exposure to ambient air. Even with these variations in odor abundance, canines previously trained to detect bulk explosive HME components were able to detect all three targets in glass and plastic TADDs for at least 18 months after loading. Detection proficiency ranged from 64% to 100% and was not found to be dependent on either age of material.

Evaluation of a sequential anaerobic-aerobic membrane bioreactor system for treatment of traditional and insensitive munitions constituents

New energetic formulations containing insensitive high explosives (IHE), such as 2,4-dinitroanisole (DNAN), 3-nitro-1,2,4-triazole-5-one (NTO), and nitroguanidine (NQ) are being developed to provide safer munitions. The addition of IHE to munitions formulations results in complex wastewaters from explosives manufacturing, load and pour operations and demilitarization activities. New technologies are required to treat those wastewaters. The core objective of this research effort was to develop and optimize a dual anaerobic-aerobic membrane bioreactor (MBR) system for treatment of wastewater containing variable mixtures of traditional energetics, IHE, and anions. The combined system proved highly effective for treatment of traditional explosives (TNT, RDX, HMX), IHE (DNAN, NTO, NQ) and anions commonly used as military oxidants (ClO4−, NO3−). The anaerobic MBR, which was operated for more than 500 d, was observed to completely degrade mg L−1 concentrations of TNT, DNAN, ClO4− and NO3− under all operational conditions, including at the lowest hydraulic residence time (HRT) tested (2.2 d). The combined system generally resulted in complete treatment of mg L−1 concentrations of RDX and HMX to <20 μg L−1, with most of the degradation occurring in the anaerobic MBR and polishing in the aerobic system. No common daughter products of DNAN, TNT, RDX, or HMX were detected in the effluent. NTO was completely transformed in the anaerobic MBR, but residual 3-amino-1,2,4-triazole-5-one (ATO) was detected in system effluent. The ATO rapidly decomposed when bleach solution was added to the final effluent. NQ was initially recalcitrant in the system, but microbial populations eventually developed that could degrade >90% of the ∼10 mg L−1 NQ entering the anaerobic MBR, with the remainder degraded to <50 μg L−1 in the aerobic system. The dual MBR system proved to be capable of complete degradation of a wide mixture of munitions constituents and was resilient to changing influent composition.

The evolutionary process and damage characteristics to the target of jet flame produced by the Al/PTFE mixed powder in a small caliber projectile with through-hole

The unsintered Al/PTFE mixed powder is a kind of active material with high energy. Different from traditional explosives, the reactive speed of the Al/PTFE mixed powder is slow, but the deflagration duration is long. When it is applied in a projectile, it can form a new weapon for special purposes. In this paper, the Al/PTFE mixed powder is applied in a projectile with a through-hole and combined with the self-energy supply activation system, a new type of small caliber ammunition is designed. The evolutionary process and duration of the jet flame under high-speed impact and static explosion are analyzed, respectively. And the damage characteristics of the jet flame to the target are analyzed from the perspectives of thermal and overpressure damages. Meanwhile, the internal energy of the jet flame in the confined space is calculated. The results show that the evolutionary process of the jet flame is similar, and the flame propagates rapidly along the crack in the target up to 175 ms under impact ignition and static explosion. The maximum overpressure and radiant temperature can reach 1.89 GPa and 5500 K, respectively. The gas’s internal energy and flash radiant energy in the confined space account for 50.9% of the total released energy.

Investigation of a non-explosive directional roof cutting technology for self-formed roadway

Traditional explosives have characteristics of high risk, large vibration, and poor directional fracturing. Consequently, an instantaneous expander with a single crack surface (IESCS), which is a novel non-explosive directional rock-breaking technique, has been developed. The directional roof-cutting mechanism of the IESCS method, driven by high-pressure gas, was theoretically analyzed. Laboratory experiments and numerical simulations proved the directional slitting effect of the IESCS method to be excellent. Compared with shaped-charge blasting, the charge of IESCS was reduced by 8.9%, but the crack rate increased by 9% in field tests. After IESCS pre-splitting, the roof directionally collapsed along the cutting line, and the gangue filled the goaf. Moreover, the directional roof cutting by the IESCS could decrease roadway stress. The average pressure of hydraulic supports on the cutting side of the roof was 31% lower than that on the non-cutting side of the roof after pre-splitting. After the self-formed roadway constructed by the IESCS was stabilized, the final relative displacement of the roof and floor was 157.3 mm, meeting the required standard of the next working face. Thus, the IESCS was effectively applied to directional roof pre-splitting. The results demonstrate the promising potential of IESCS in the mining and geotechnical fields.

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.

A new Ignition-Growth reaction rate model for shock initiation

Accurately predicting reactive flow is a challenge when characterizing an explosive under external shock stimuli as the shock initiation time is on the order of a microsecond. The present study constructs a new Ignition-Growth reaction rate model, which can describe the shock initiation processes of explosives with different initial densities, particle sizes and loading pressures by only one set of model parameters. Compared with the Lee-Tarver reaction rate model, the new Ignition-Growth reaction rate model describes better the shock initiation process of explosives and requires fewer model parameters. Moreover, the shock initiation of a 2, 4-Dinitroanisole (DNAN)-based melt-cast explosive RDA-2 (DNAN/HMX (octahydro- 1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazoncine)/aluminum) are investigated both experimentally and numerically. A series of shock initiation experiments is performed with manganin piezoresistive pressure gauges and corresponding numerical simulations are carried out with the new Ignition-Growth reaction rate model. The RDA-2 explosive is found to have higher critical initiation pressure and lower shock sensitivity than traditional explosives (such as the Comp. B explosive). The calibrated reaction rate model parameters of RDA-2 could provide numerical basis for its further application.

A Functional Safety Assessment Methodology for Explosion Protection with Application to a Variable Frequency Drive System

Modern explosion protection equipment, protected by traditional explosion protection technology (as defined by the international electrotechnical commission (IEC) publication IEC60079-ff series standards) and electrical/electronic/programmable electronic (E/E/PE) safety-related systems, is becoming ever more complex in coal mine development and petrochemical industry; thus, the possibility of failures in their operation is also growing. It is well-known that E/E/PE safety-related systems can be used to actively control dangerous sources, with real and expected levels of reliability, if they have been qualified according to the IEC61508-ff series standards. To uniformly evaluate the safety integrity level (SIL) of the explosion protection function of traditional explosion protection technology and E/E/PE safety-related system technology, this study analyzed the ability of these types of protection to remove the ignition risk residual, evaluating the failure rates of safety devices. The key objective of this paper is the presentation of a new equipment protection level (EPL) assessment method for explosion protection equipment based on a functional safety assessment. The method is applied to a variable frequency drive (VFD) system, and the results show that the EPL of the explosion protection equipment evaluated by this method is consistent with the EPL corresponding to the traditional explosion protection type of the IEC60079-ff series standard. Meanwhile, the flexible configuration of explosion protection safety devices and E/E/PE safety-related systems enables explosion protection equipment of different EPL levels to be designed.

A comprehensive study of the dissolution process of N-oxide based explosives in deep eutectic solvents

N-oxide based explosives display better explosive performances than traditional explosives, because of the introduction of N-oxide group with strong hydrogen bonding (H-bonding). However, the strong H-bonding results in poor dissolution of N-oxide based explosives, and thus poses a significant challenge for their potential applications. Deep eutectic solvents (DESs), a new generation of green solvents, display promising dissolution toward strong H-bonding materials in recent years. In this study, 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) was used as a prototype of N-oxide based explosives to study the dissolution in DESs. The dissolution conditions for LLM-105 were optimized by using different types of DESs. The DES-3-2 based on choline chloride and urea displayed higher dissolving capacity with 0.52 g/100 g at 80 °C, which was determined by traditionally gravimetric method. Further, the dissolution process of LLM-105 in DES-3-2 under different temperatures was investigated by comprehensive analysis including ultra-high-performance liquid chromatography, high-resolution mass spectrum and theoretical calculations. The dissolution of LLM-105 under ≤80 °C was demonstrated to be real dissolution referring to the formation of Zundel-type complex and Meisenheimer complex between DES-3-2 and LLM-105. Abnormally high solubility of LLM-105 at >80 °C was attributed to the self-collapse of its H-bonding network by losing a nitro group and an oxygen of N-oxide group.

Outdoor dissolution and photodegradation of insensitive munitions formulations IMX-101 and IMX-104: Photolytic transformation pathway and mechanism study

New munition compounds have been developed to replace traditional explosives to prevent unintended detonations. However, insensitive munitions (IM) can leave large proportion of unexploded charge in the field, where it is subjected to photodegradation and dissolution in precipitation. The photolytic reactions occurring on the surfaces of IMX-101 and IMX-104 formulations and the subsequent fate of photolytic products in the environment were thoroughly investigated. The constituents of IMX-101 and IMX-104 formulations dissolve sequentially under rainfall in the order of aqueous solubility: 3-nitro-1,2,4-triazol-5-one (NTO) > nitroguanidine (NQ) > 2,4-dinitroanisole (DNAN) > 1,3,5-hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). A linear relationship between DNAN dissolution and rainwater volume was observed (r2: 0.86–0.99). It was estimated that it would take 16–228 years to completely dissolve these formulation particles under natural environmental conditions in Oracle, AZ. We used LC/MS/MS and GC/MS to examine the dissolution samples from IMX-101 and 104 particles exposed to rainfall and sunlight and found six DNAN photo-transformation products including 2-methoxy-5-nitrophenol, 4-methoxy-3-nitrophenol, 4-methoxy-3-nitroaniline, 2-methoxy-5-nitroaniline, 2,4-dinitrophenol, and methoxy-dinitrophenol, which are in good agreement with computational modeling results of bond strengths. The main DNAN photodegradation pathways are therefore proposed. Predicted eco-toxicity values suggested that the parent compound DNAN, methoxy-nitrophenols, methoxy-nitroanilines and the other two products (2,4-dinitrophenol and methoxy-dinitrophenol) would be harmful to fish and daphnid. Our study provides improved insight about the rain dissolution and photochemical behavior of IM formulations under natural conditions, which helps to form target-oriented strategies to mitigate explosive contamination in military training sites.

An Experimental Investigation of Corner‐Turning Performance in a Large Double Cylinder of Highly‐Insensitive Explosive

AbstractWhen creating ignition and growth models for new explosive formulations, it is crucial to have a complete understanding of transverse detonation growth within the material to accurately predict corner‐turning performance in various geometries. This understanding is particularly important when designing a direct replacement for an existing explosive, typically with requirements to maintain function in terms of both initiation and end effects/lethality. While there have been many corner‐turning tests developed and successfully utilized over the last 60 years, many of the experimental designs favor traditional explosives that tend to exhibit ideal growth behavior. Many of the traditional corner‐turning tests exhibit prohibitive complications when faced with geometric scale‐up to accommodate large critical diameters that often accompany insensitive behavior. In an effort to address this shortcoming, the authors propose a corner‐turning test that can easily scale to accommodate a wide range of critical diameters and introduces modern diagnostics to provide additional data known to be useful for model development. As a case study for IMX‐104, the work herein uses a combination of streaked fiber optics and photonic Doppler velocimetry probes (PDV) to investigate corner turning within a large double cylinder geometry. Additionally, diameter effects on detonation velocity measurements, front wave curvature, and extent of reaction at various PDV probe locations are investigated using the same diagnostics. These experimental results have since been used to improve an IMX‐104 ignition and growth model that has been used to support the development of numerous warhead designs – notably the 155 mm family of artillery munitions.

Research on Interface Characteristics and Mechanical Properties of 6061 Al Alloy and Q235a Steel by Hot Melt-Explosive Compression Bonding

In order to solve the shortcomings of the traditional explosion welding method for direct magnesia-aluminum alloy and steel welding, a processing method of groove hot casting plus explosion compression bonding (HCECB) was put forward, and the related theory of hot-melt metal plus explosion bonding was also proposed. Taking 6061 aluminum and Q235a steel as examples, the hot casting plus explosion compression test was carried out by the prefabrication of a dovetail groove on Q235a steel plate and the microstructure and mechanical properties of the interface were analyzed. The results showed that the 6061 aluminum/Q235a steel can be directly combined by the HCECB method. The interface is mainly irregularly microwave-shaped and straight-shaped with no defects, such as melting layer, holes and cracks, found. The hardness of the upper interface of the dovetail groove is larger than that far away from the welding interface, while the hardness of the lower interface is the same as that far away from the interface. The tensile and shear test results show that the shear strength is greater than 80 MPa, which meets the requirements of aluminum-steel composite plate bonding strength.

Covalent bonding of aromatic amine daughter products of 2,4-dinitroanisole (DNAN) with model quinone compounds representing humus via nucleophilic addition.

2,4-Dinitroanisole (DNAN) is a component of insensitive munitions (IM), which are replacing traditional explosives due to their improved safety. Incomplete IM combustion releases DNAN onto the soil, where it can leach into the subsurface with rainwater, encounter anoxic conditions, and undergo (a)biotic reduction to aromatic amines 2-methoxy-5-nitroaniline (MENA), 4-methoxy-3-nitroaniline (iMENA, isomer of MENA), and 2,4-diaminoanisole (DAAN). We report here studies of nucleophilic addition mechanisms that may account for the sequestration of aromatic amine daughter products of DNAN into soil organic matter (humus), effectively removing these toxic compounds from the aqueous environment. Because quinones are important moieties in humus, we incubated MENA, iMENA, DAAN, and related analogs with model compounds 1,4-benzoquinone and 2,3-dimethyl-1,4-benzoquinone under anoxic conditions. Mass spectrometry and ultra-high performance liquid chromatography revealed that the aromatic amines had covalently bonded to either carbonyl carbons or ring carbons β to carbonyl carbons of the quinones, producing a mixture of imines and Michael adducts, respectively. These products formed rapidly and accumulated in the one-to four-day incubations. Nucleophilic addition reactions, which do not require catalysis or oxic conditions, are proposed as a mechanism resulting in the binding of DNAN to soil observed in previous studies. To remediate sites contaminated with DNAN or other nitroaromatics, reducing conditions and humus amendments may promote their immobilization into the soil matrix.

Hyperspectral imaging and remote trace detection of cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5 d] imidazole (BCHMX) compared with traditional explosives using laser induced fluorescence

cis-1,3,4,6-Tetranitrooctahydroimidazo-[4,5 d] imidazole (BCHMX) is an advanced energetic compound that expected to spread worldwide in the near future. Since, no approved remote detection methods were reported in current literature for this material, we performed hyper-spectral imaging and laser induced fluorescence (LIF) to a BCHMX sample under low laser fluence for determining the optimum laser wavelength used in any future BCHMX-LIF based remote detection systems. For this purpose, an experimental setup consisted of a sun spectrum lamp and hyper-spectral camera was built to illuminate and image white powder samples of BCHMX in comparison with the traditional explosives, HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane), RDX (1,3,5-trinitro-1,3,5-triazacyclohexane), PETN (2,2-Bis[(nitroxy)methyl]propane-1,3-diyldinitrate). The imaging reveals strong BCHMX sample absorption contrast among other samples at wavelength ranging from 400 to 410 nm. When light source was replaced by a 405 nm laser diode illuminator, a strong BCHMX sample LIF at the spectral range from 425 to 700 nm was observed under low laser fluence condition of 0.1 mJ/cm2. Finally, we demonstrated successfully the ability of the 405 nm LIF and the hyperspectral imaging technique to detect finger print traces of BCHMX on white cellulose fabric from a distance of 15 m and a detection limit of 1 μg/cm2.

Theoretical Model of Radial Scattering Velocity of Fragments of the Reactive Core PELE Projectile

PELE projectile is a new type of armor-piercing warhead and has a more obvious fragmentation effect, which solves the problem of insufficient after-effects of conventional armor-piercing projectiles. Reactive material is a new type of energetic material, which has some characteristics similar to the traditional explosives but has better mechanical properties. Reactive material is insensitive under normal conditions, and it can release huge energy under external impact loading. This paper hopes to study the application of reactive materials to the inner core of PELE projectiles to further improve the fragmentation effect of PELE projectiles. The fragmentation effect of PELE projectile is mainly reflected in the radial scattering velocity of fragments after it perforates the target plate. In this paper, three energy sources for the radial scattering of fragments were obtained by analyzing the penetration process of PELE projectile, that is, the axial kinetic energy of outer casing, the radial compression potential energy generated by the inner core to the outer casing, and the chemical energy released by the reactive core material. Based on the simplification and assumptions, the theoretical model of radial scattering velocity of fragments of the reactive core PELE projectile was established. In addition, numerical simulations were carried out to verify the theoretical model. The results show that the numerical simulation results are in good agreement with the theoretical calculation results, which indicates that the model established in this paper is scientific and reasonable. The reactive core PELE projectile has a more significant fragmentation effect, which further enhances the comprehensive damage power of traditional PELE projectile. The theoretical model established in this paper can quickly assess the power of reactive core PELE projectile’s fragmentation effect, which can be used to provide guidance and reference for engineering application.

Computational insight into energetic cage derivatives based on hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine

AbstractFour novel cage compounds were designed by introducing –N(NO2)CH2–, –N(NO2)O–, –N(NO2)N(NO2)–, and –N=N– linkages into the RDX (hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine) skeleton. Their molecular geometry, electronic structure, heat of formation, and detonation properties were systematically studied using density functional theory (DFT). In addition, the most stable dimers of the four compounds were constructed to further investigate their stability based on intermolecular interactions. It is found that the unconventional CH⋯O interactions would be the dominant driving force when the title compounds form crystals. Compared with the traditional explosives, the compounds with higher detonation properties and lower impact sensitivity will be considered as promising candidates for high energy density compounds. Our results indicate that our innovative design strategy is extremely useful for developing novel energetic compounds.