Insensitive Explosives Research Articles

Optical emission behaviors of C, Al, Ti, Fe, Cu, Mo, Ag, Ta, and W wire explosions in gaseous media

Electrical explosion of wires (EEW) is a promising method for nanopowders preparation and insensitive explosives ignition. Plasma radiation plays a key role in the ignition process while little attention has been paid on this phenomenon before. This letter introduces optical emission behaviors of electrical explosions for nine materials in air, Helium, and Argon with the SWE-2 platform. Experimental results indicated that the light intensity for non-refractory metals decayed rapidly after the discharge ended. In contrast, for refractory metals, the emission continued to increase and lasted for a long period after the discharge ceased. As for spectra, the emission consisted of line and continuous spectra. With the atomic number increased, the density of lines grew rapidly, leading to a “continuous” appearance.

Molecular design on a new family of azaoxaadamantane cage compounds as potential high-energy density compounds

A new family of azaoxaadamantane cage compounds were firstly designed by introducing the oxygen atom into hexanitrohexaazaoxaadmantane (HNHAA) to replace the N–NO2 group. Their properties including heats of formation (HOFs), detonation properties, strain energies, thermal stability, and sensitivity were extensively studied by using density functional theory. All of the title compounds exhibit surprisingly high density (ρ > 2.01 g/cm3) and excellent detonation properties (detonation velocity (D) > 9.29 km/s and detonation pressure (P) > 40.80 GPa). In particular, B (4,8,9,10-tetraazadioxaadamantane) and C (6,8,9,10-tetraazadioxaadamantane) have a remarkably high D and P values (9.70 km/s and 44.45 GPa, respectively), which are higher than that of HNHAA or CL-20. All of the title compound have higher thermal stability and lower sensitivity (h50 > 19.58 cm) compared with the parent compound HNHAA. Three triazatrioxaadamantane cage compounds, D (6,8,9-triazatrioxaadamantane), E (6,8,10-triazatrioxaadamantane), and F (8,9,10-triazatrioxaadamantane), are expected to be relatively insensitive explosives. All of the title compounds exhibit a combination of high denotation properties, good thermal stability, and low insensitivity.

The effect of different additives on safety manipulation of cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX)

In this work, new cyclic nitramine named cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX) was premixed with insensitive explosives (3-nitro-1,2,4-triazol-5-one, NTO and1,1-diamino-2,2-dinitroethene, FOX) and with two cyclic nitramines (1,3,5-trinitro-1,3,5-triazinane, RDXand, 1,3,5,7-tetranitro-1,3,5,7-tetrazocane, HMX) and bonded by polydimethyl-siloxane (PDMS) binder.Impact and friction sensitivities were evaluated. Detonation velocity was measured and the detonationcharacteristics were calculated by EXPLO 5 thermodynamic code. Relative explosive strength wasdetermined by using the ballistic mortar test. The results showed a great positive influence on the sensitivityof BCHMX due to the addition of the insensitive explosive (NTO, FOX-7) however the performance wasdecreased. On the other side, mixing the nitramines improved the performance with reduction of BCHMXsensitivity. PDMS binder succeed to decrease the sensitivity of all the studied mixtures.

Eutectics of Erythritol Tetranitrate

With the recent availability of erythritol as an artificial sweetener, the synthesis of erythritol tetranitrate (ETN) has become economically feasible. This paper examines the eutectics of ETN, to see if it can be a useful component in melt-casted explosive formulations. To this end, we report several novel ETN–energetic eutectics, correct ratios, and melt-temperature for a previously reported eutectic, and we examine a new eutectic composed of insensitive explosives.

Synthesis and Theoretical Studies of a New Insensitive Explosive, 2'-methyl-3-nitro-2'H-[1, 3'-bi(1,2,4-triazole)]-5, 5'-diamine

Synthesis and Theoretical Studies of a New Insensitive Explosive, 2'-methyl-3-nitro-2'H-[1, 3'-bi(1,2,4-triazole)]-5, 5'-diamine

Initial Decomposition of Condensed-Phase 1,3,5-Triamino-2,4,6-trinitrobenzene under Shock Loading

We study the intrinsic shock decomposition mechanism of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) via quantum-based multiscale molecular dynamics methods. Some distinctive and novel insights are obtained based on our simulation results. The reaction is always initiated by hydrogen transfer both in intra- and intermolecular conditions. The carbon atom is mostly oxidized by nitro O directly. The earliest gas product NO2 is produced with the cleavage of C-NO2. The initial N2 mainly derives from the interaction between NO and TATB molecular residues. More intriguingly, we detect 28 kinds of heterocyclic structures involved in the TATB decomposition process. Most of the newly formed C–N heterocycles possess high stability, which obviously inhibit the further reaction toward releasing C oxides and N2. These results reveal not only the early shock decomposition properties of TATB but also the different reaction mechanisms between sensitive and insensitive explosives.

Compatibility of 2, 4, 6, 8, 10,12-Hexanitrohexaazaisowurtzitane with a Selection of Insensitive Explosives

Thermal techniques (differential scanning calorimetry (DSC) and the vacuum stability test (VST)), according to STANAG 4147, and non-thermal techniques (Fourier transform infrared (FTIR) spectrometry and X-ray diffractometry (XRD)) were used to examine compatibility issues for 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (CL-20) with a selection of insensitive explosives, including nitroguanidine (NQ), 2,4,6-trinitrotoluene (TNT), 2,6-diamino-3,5-dinitropyridine-1-oxide (ANPyO), 2,4,6-triamino-1,3,5-trinitrobenzene (TATB), 3-nitro-1,2,4-triazol-5-one (NTO) and 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105). DSC measurements showed that ANPyO, TATB, NTO and LLM-105 were compatible with CL-20. The compatibility of CL-20/NQ, CL-20/TNT, CL-20/ANPyO, CL-20/TATB, CL-20/NTO and CL-20/LLM-105 mixtures was further explored using the VST, which revealed that all the selected insensitive explosives were compatible with CL-20. Possible chemical interactions were suspected for CL-20/TATB from the FTIR results and for CL-20/NTO from XRD analysis. In summary, ANPyO and LLM-105 demonstrated the optimal compatibility with CL-20.

Immobilized Biocatalyst for Detection and Destruction of the Insensitive Explosive, 2,4-Dinitroanisole (DNAN).

Accurate and convenient detection of explosive components is vital for a wide spectrum of applications ranging from national security and demilitarization to environmental monitoring and restoration. With the increasing use of DNAN as a replacement for 2,4,6-trinitrotoluene (TNT) in insensitive explosive formulations, there has been a growing interest in strategies to minimize its release and to understand and predict its behavior in the environment. Consequently, a convenient tool for its detection and destruction could enable development of more effective decontamination and demilitarization strategies. Biosensors and biocatalysts have limited applicability to the more traditional explosives because of the inherent limitations of the relevant enzymes. Here, we report a highly specific, convenient and robust biocatalyst based on a novel ether hydrolase enzyme, DNAN demethylase (that requires no cofactors), from a Nocardioides strain that can mineralize DNAN. Biogenic silica encapsulation was used to stabilize the enzyme and enable it to be packed into a model microcolumn for application as a biosensor or as a bioreactor for continuous destruction of DNAN. The immobilized enzyme was stable and not inhibited by other insensitive munitions constituents. An alternative method for DNAN detection involved coating the encapsulated enzyme on cellulose filter paper. The hydrolase based biocatalyst could provide the basis for a wide spectrum of applications including detection, identification, destruction or inertion of explosives containing DNAN (demilitarization operations), and for environmental restorations.

Covalent and Ionic Insensitive High‐Explosives

AbstractOngoing research into new insensitive energetic materials with low sensitivity toward accidental stimuli, high thermal stability and high performance characteristics is undertaken in many research groups worldwide. In order to obtain promising compounds, which fulfil the sensitivity, stability, and performance requirements, researchers use many different strategies. One of the most promising approaches is the synthesis of novel explosives with tailored physico‐chemical properties. In this review the synthesis and properties of some both covalent (NTO, TEX, FOX‐7, ADNP, DNPPs) and ionic (salts of ANDP and DNPP) insensitive explosives are presented, which are of high interest to this field of research.

Insensitive High Explosives II: 3,3′‐Diamino‐4,4′‐azoxyfurazan (DAAF)

AbstractThis paper reviews the synthesis, properties, performance, and safety of the insensitive explosive 3,3′‐diamino‐4,4′‐azoxyfurazan (DAAF, C4H4N8O3), CAS‐No. [78644‐89‐0], and 18 formulations based on it. Though having a moderate crystal density only, DAAF offers high positive heat of formation and hence superior performance when compared with TATB. It is friction and impact insensitive but is more sensitive to shock than TATB and has an exceptionally small critical diameter and performs very well at low temperatures unlike other insensitive explosives. 39 references to the public domain are given. For Part I see Ref. [1].

Ageing of Australian DNAN Based Melt‐Cast Insensitive Explosives

Abstract2,4‐Dinitroanisole (DNAN) is a new melt‐cast matrix ingredient that replaces traditional TNT in TNT‐based melt‐cast explosives. Aside from sensitiveness improvements, the use of DNAN allows for the continued operation of existing melt‐cast facilities (for example the Australian Munitions plants located at Mulwala and Benalla) without the need for major plant modifications. Researchers at Defence Science and Technology Group (DST Group) have developed several DNAN based formulations that have been extensively characterized. In an effort to better understand the ageing properties of these formulations, an accelerated ageing program was undertaken. Testing was conducted under two different ageing conditions; the first test condition was conducted at a constant 60 °C with ambient humidity and the second test condition was the A2 diurnal cycle (representative of hot dry climates). Analysis of the formulation density, sensitiveness, mechanical and thermal properties was made at three‐month intervals for a period of 12 months and results compared with conventional explosives similarly aged. For all DNAN‐based formulations there was negligible change in impact, friction, electrostatic discharge, and thermal testing over time. These results highlight the ability of the ARX formulations to diurnal temperature cycling and to hold favorable sensitiveness properties to various stimuli.

Mass Dependent of Explosion Probability of RDX, Tetryl, and a PBX Powder in Drop Hammer Test

AbstractSeries of Drop Weight Tests with varying sample mass of RDX, tetryl, and a PBX molding powder were carried out and the dramatic effects of sample mass on the explosion probability were obtained. The experimental results indicate that the explosion probability will firstly increase and subsequently decrease when the mass of sample reduces and also it shows the explosion probability is also related with the coverage area of the sample on the impact pillar. The explosion probability reached the maximum when the impact pillar was fully covered by the sample. A Dual‐factor‐competition Model is proposed in this work, which is able to predict the correlation between the explosion probability and sample mass. The response characteristic obtained can help to redesign the sensitivity test and provide a new way to distinguish the impact sensitiveness of insensitive explosives by reducing the sample mass.

TEX – 4,10‐Dinitro‐2,6,8,12‐tetraoxa‐4,10‐diazatetracyclo[5.5.0.05,9.03,11]‐dodecane – Review of a Promising High Density Insensitive Energetic Material

AbstractThe title compound 4,10‐dinitro‐2,6,8,12‐tetraoxa‐4,10‐diazatetracyclo[5.5.0.05,903,11]‐dodecane – often referred to as TEX – is a very promising newcomer in the field of insensitive explosives. It is easily synthesized with good yield from cheap starting materials. TEX offers a respectable high ambient temperature crystal density (1.985 g cm−3) and hence good detonation velocity and pressure but is fairly insensitive towards mechanical and thermal stimuli. It has a large critical diameter and is advantageously used in large charges. 76 references to the public domain are given.

Searching for a new family of insensitive high explosives by introducing N hybridization and N-oxides into a cage cubane.

A new family of energetic azacubane N-oxides were designed by introducing N-oxides into azacubanes and investigated by using density functional theory. Introducing the N-oxides into the azacubanes could improve their detonation performance significantly due to the increase of the OB and ρ but would also increase the sensitivity to some extent. These effects would be further enhanced as the numbers of N-oxides increase. Among all the designed azacubane N-oxides, D6-4 (1,3,5,7-tetraazacubane-1,3,5,7-tetraoxides) has higher detonation performance than one famous high explosive HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane) and lower sensitivity than one very insensitive explosive TNT (1-methyl-2,4,6-trinitrobenzene), suggesting that its overall performance is outstanding and may be considered as the potential candidate of insensitive high explosives. The internal small cage C-N skeleton of D6-4 is surrounded by the external big cage hydrogen bonds and this special double cage structure may be an important reason why it has low sensitivity.

Energetic Derivatives of 2‐Nitrimino‐5,6‐dinitro‐benzimidazole

Abstract2‐Nitrimino‐5,6‐dinitrobenzimidazole (1) was synthesized by nitration of 2‐aminobenzimidazole at ambient temperature in good yield. In order to explore new insensitive explosives four energetic nitrogen‐rich 1 : 1 salts such as the guanidinium (1a), aminoguanidinium (1b), triaminoguanidinium (1c) and hydroxylammonium (1d) were synthesized either by facile acid/base or in situ metathesis reaction. In addition 2‐nitrobenzimidazole (2) was synthesized by the reaction of 2‐aminobenzimidazole using potassium hyperoxide in THF. Different nitration methods were tested to obtain a theoretically 2,4,5,6,7‐pentanitrobenzimidazole but only the already known 4,5,6,7‐tetranitrobenzimidazol‐2‐one (3) could be isolated. All synthesized compounds were characterized especially by low temperature X‐ray diffraction, CHN elemental analysis and 1H and 13C NMR spectroscopy. The heat of formation of all new synthesized compounds was calculated using CBS‐4M electronic enthalpies in combination with the atomization method to calculate their detonation parameters with the EXPLO 5 V5.05 computer code.

Aerobic Degradation of N-Methyl-4-Nitroaniline (MNA) by Pseudomonas sp. Strain FK357 Isolated from Soil

N-Methyl-4-nitroaniline (MNA) is used as an additive to lower the melting temperature of energetic materials in the synthesis of insensitive explosives. Although the biotransformation of MNA under anaerobic condition has been reported, its aerobic microbial degradation has not been documented yet. A soil microcosms study showed the efficient aerobic degradation of MNA by the inhabitant soil microorganisms. An aerobic bacterium, Pseudomonas sp. strain FK357, able to utilize MNA as the sole carbon, nitrogen, and energy source, was isolated from soil microcosms. HPLC and GC-MS analysis of the samples obtained from growth and resting cell studies showed the formation of 4-nitroaniline (4-NA), 4-aminophenol (4-AP), and 1, 2, 4-benzenetriol (BT) as major metabolic intermediates in the MNA degradation pathway. Enzymatic assay carried out on cell-free lysates of MNA grown cells confirmed N-demethylation reaction is the first step of MNA degradation with the formation of 4-NA and formaldehyde products. Flavin-dependent transformation of 4-NA to 4-AP in cell extracts demonstrated that the second step of MNA degradation is a monooxygenation. Furthermore, conversion of 4-AP to BT by MNA grown cells indicates the involvement of oxidative deamination (release of NH2 substituent) reaction in third step of MNA degradation. Subsequent degradation of BT occurs by the action of benzenetriol 1, 2-dioxygenase as reported for the degradation of 4-nitrophenol. This is the first report on aerobic degradation of MNA by a single bacterium along with elucidation of metabolic pathway.

Oxalylhydrazinium Nitrate and Dinitrate—Efficiency Meets Performance

Oxalylhydrazinium nitrate (OHN) and dinitrate (OHDN) were synthesized by protonation of oxalyldihydrazide with nitric acid. The synthesis is extremely cost effective (∼$40/kg at the lab scale) and can be carried out in large scales and very good yields. OHN and OHDN were intensively characterized by low-temperature X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and vibrational spectroscopy. These new organic nitrate salts could be used as powerful ingredients in energetic formulations due to their low sensitivities (measured by Bundesanstalt für Materialforschung und Pröfung methods). Their thermal stability was investigated by differential scanning calorimetry (DSC) measurements. Further thermal studies of OHN showed compatibility with TNT (2,4,6-trinitrotoluene), DNAN (2,4-dinitroanisole), and RDX (1,3,5-trinitro-1,3,5-triazinane). The theoretical detonation and propulsion parameters of OHN and OHDN were calculated with the EXPLO5.5 code and compared to well-known insensitive explosives. The aquatic toxicity of OHN was determined by the luminescent bacteria inhibition test, yielding a much lower toxicity than RDX.

A DFT Study on the Structures and Energies of Isomers of 4‐Amino‐1,3‐dinitro‐1,2,4‐triazol‐5‐one‐2‐oxide: New High Energy Density Compounds

AbstractIsomers of 4‐amino‐1,3‐dinitrotriazol‐5‐one‐2‐oxide (ADNTONO) are of interest in the contest of insensitive explosives and were found to have true local energy minima at the DFT‐B3LYP/aug‐cc‐pVDZ level. The optimized structures, vibrational frequencies and thermodynamic values for triazol‐5‐one N‐oxides were obtained in their ground state. Kamlet‐Jacob equations were used to evaluate the performance properties. The detonation properties of ADNTONO (D=10.15 to 10.46 km s−1, P=50.86 to 54.25 GPa) are higher compared with those of 1,1‐diamino‐2,2‐dinitroethylene (D=8.87 km s−1, P=32.75 GPa), 5‐nitro‐1,2,4‐triazol‐3‐one (D=8.56 km s−1, P=31.12 GPa), 1,2,4,5‐tetrazine‐3,6‐diamine‐1,4‐dioxide (D=8.78 km s−1, P=31.0 GPa), 1‐amino‐3,4,5‐trinitropyrazole (D=9.31 km s−1, P=40.13 GPa), 4,4′‐dinitro‐3,3′‐bifurazan (D=8.80 km s−1, P=35.60 GPa) and 3,4‐bis(3‐nitrofurazan‐4‐yl)furoxan (D=9.25 km s−1, P=39.54 GPa). The NH2 group(s) appears to be particularly promising area for investigation since it may lead to two desirable consequences of higher stability (insensitivity), higher density, and thus detonation velocity and pressure.

EVALUATION OF GIM AS A GREENER INSENSITIVE MELT-CAST EXPLOSIVE

For years, DRDC Valcartier has invested efforts at developing energetic thermoplastic elastomers (ETPEs) based on linear glycidyl azide polymers to serve as energetic binders and replacing the thermoset matrix in insensitive explosives. It was first observed that introducing ETPEs in their melted form was not an easy task because high and nonpractical viscosities were encountered in the process. It was discovered that 2,4,6-trinitrotoluene (TNT) could be used in its melted form as an organic solvent to dissolve the ETPE and allow its incorporation into the insensitive formulations. Using these ETPEs led to the development of a greener insensitive melt-cast explosive named green insensitive munitions (GIM). This new explosive was intensely studied. The mechanical properties and proportions of ETPE in the formulations were optimized to obtain a melt cast with low viscosity while leading to an insensitive explosive formulation. Work was conducted on GIM explosives to test their performance and sensitivity, fate and behavior with regard to the environment, their recycling capability, and toxicity. This paper describes the results of all experiments conducted so far to test these aspects of GIM explosives. The preparation of the ETPEs and the GIM explosives will also be briefly described.

A Predictive Study on Molecular and Explosive Properties of 1-Aminoimidazole Derivatives

Molecular structures and chemical properties of 1-aminoimidazole derivatives have been investigated at high levels of density functional theories. Heat of formation, density, explosive performances and impact sensitivities have been estimated at the global minimum of potential energy surface. As more nitro groups are introduced, the explosive performances of 1-aminoimidazole derivatives are enhanced, while the impact sensitivity becomes more sensitive. A two-dimensional plot between explosive performance and impact sensitivity has been utilized to comprehend the technical status of new explosive candidates. Based on locations in the two-dimensional plot, 1-aminodinitroimidzole isomers appears to have a potential to be good candidates for insensitive explosives, and 1-aminotrinitroimidazole may become a powerful explosive molecule whose behavior is quite close to HMX.