Calculated Detonation Velocity Research Articles

Characterization and properties of a new insensitive explosive co-crystal composed of trinitrotoluene and pyrene

A new energetic co-crystal of trinitrotoluene (TNT) and pyrene (PYRN) with a 1:1 molar ratio was prepared by a slow solvent evaporation technique. Co-crystal physicochemical properties have also been examined using optical microscopy, powder X-ray diffraction, single crystal X-ray diffraction, and differential scanning calorimetry. The results of single-crystal X-ray diffraction and non-covalent interaction calculations showed that non-covalent interactions (donor–acceptor π-π interaction) govern the structures of the TNT:PYRN co-crystal. The experimental and theoretical outcomes supported each other in the study. Thermal stability, impact sensitivity, and detonation performance of the co-crystal were investigated. DSC measurement indicates that the co-crystal has a melting point of 167 °C and a decomposition temperature of 293 °C, indicating outstanding thermal stability. The co-crystal was found to be less impact-sensitive than TNT using the BAM fall hammer instrument. Furthermore, the calculated detonation velocity and detonation pressure of the co-crystal are 5.29 km·s−1 and 8.48 G Pa, respectively. As an outcome, the TNT:PYRN co-crystal may be a promising intermediate energy explosive with low sensitivity and, as such, may be a desirable explosive alternative in the future instead of TNT for low-vulnerability formulations.

Crowding-out strategy to enhance energetics of 3-nitro-1,2,4-triazol-5-one based E-MOFs at the molecular level through adjusting pH

Based on the combination of coordination chemistry and the noncovalent interactions, the crowding-out concept is put forward to fundamentally solve the problem that the structural H2O in E-MOFs results in a decreased stability, density and heats of detonation. In this paper, “filling” the 4,4′-azobis(1,2,4-triazole) (ATRZ) molecules into the structure of NTO (3-nitro-1,2,4-triazol-5-one) E-MOFs, the coordination and crystal water molecules were successfully extruded to gain anhydrous [Cu(NTO)2(ATRZ)] (a) / [Zn(NTO)2(ATRZ)] (c) and hypohydrous [Co(NTO)2(ATRZ)(H2O)2]·ATRZ (b) by adjusting pH at room temperature and pressure, which is friendly for energetic materials. With the addition of ATRZ (high HOF) and the departure of water, the ΔfHmθ of them are becoming higher. The heat of detonation is increased by 1.33, 2.39 and 0.74 times respectively and the calculated detonation velocity of three compounds is enhanced by about 1000 m s−1 contrasted to the corresponding hydrates. The removal of water molecules did not result in a high sensitivity. More importantly, as potential catalysts for AP-based solid propellants, a and c still showed excellent catalysis for the thermal decomposition of AP (ammonium perchlorate) after modification. In this study, it took a whole new idea to radically solve the difficulties in the area of E-MOFs by a simple and original way, and this is a significant innovation for the safety of energetic material.

Self-Assembly Fabrication of Energetic Perchlorates with High Density and Near-Infrared Laser Ignition Capacity

In this work, four energetic compounds (1–4) were prepared through the combination of nitrogen-rich heterocyclic fused-ring compounds and perchloric acid via a self-assembly methodology. The densities of these compounds were higher than 1.92 g cm–3, and compound 2 exhibited the highest density of 2.04 g cm–3, which exceeded those of most of the traditional energetic compounds. The calculated detonation velocity, detonation pressure, and specific impulse of compound 2 were 9317 m s–1, 41.1 GPa, and 264 s, respectively; these values were greater than those of high-energy and high-density material 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX). Furthermore, compound 1 is the first example of metal-free energetic materials with near-infrared (λ = 1064 nm) laser ignition ability. The high densities and excellent energetic performances of these compounds indicate that self-assembly is a promising approach for the development of advanced energetic materials.

Azido azole-1,3,4-triazine fused energetic materials: A bioinspired strategy for tuning thermal stability and sensitivity of metal-free primary explosives via hierarchical hydrogen-bond self-assembly

Primary explosives are useful but they usually pose low thermal stability and underlying safety threat to manufacturers and users. It is highly desirable yet challenging to develop next-generation primary explosives with lead-free, environmentally friendly, high-dense, thermostable and safe organic energetic materials for replacement. Here, inspired by biosystem’s architecture, we report a simple and efficient hierarchical hydrogen-bond self-assembly strategy to synthesize high-performance primary explosives with enhanced thermal stability (Tonset > 200 °C) and decreased sensitivity (40 J). Owing to the above-efficient strategy, 7-azide-3-(1H-tetrazol-5-yl)-[1,2,4]triazolo[5,1-c] [1,2,4]triazin-4-amine-2- oxide (EM-4) and 7-azide-4-amino-3-nitro-[1,2,4]triazolo[5,1-c][1,2,4]triazine (EM-6) feature high densities of 1.825 and 1.816 g cm−3, much superior to their analogues 7-azide-3-(1H-tetrazol-5-yl)-[1,2,4]triazolo[5,1-c][1,2,4]triazin-4-amine (EM-3) and 8-azide-4-amino-3,7-dinitropyrazolo-[5,1-c][1,2,4]triazine (EM-9), comparable to that of 6-azido-8-nitrotetrazolo[1,5-b]-pyridazine-7-amine (ANTP). Meanwhile, EM-3 (Td = 225 °C), EM-4 (Td = 290 °C) and EM-6 (Td = 210 °C) exhibit better thermal stability and lower sensitivities (IS = 40 J) than those representative metal-free primary explosives (Td = 114–193 °C, IS = 0.25–17 J). The as-synthesized materials all feature superior performance to those of commercially scale-up and industrial applicable primary explosive 2-diazo-4,6-dinitrophenol (DDNP). Moreover, the calculated detonation velocity of EM-6 reaches up to 9029 m s−1, which is comparable to that of 6-nitro-7-azido-pyazol[3,4-d][1,2,3]triazine-2-oxide (ICM-103) but EM-6 features better thermal stability and safety performance. Bioinspired organic primary explosive may open a new gate for the design and development of more thermostable, higher dense and safer initiating substances towards future advanced applications.

Co-agglomerated crystals of 2,2′,4,4′,6,6′-hexanitro -stilbene/-azobenzene with attractive nitramines

Co-agglomerated crystals (CACs) of trans-2,2,4,4′,6,6′-hexanitrostilbene (HNS) and trans-2,2′,4,4′,6,6′-hexanitroazobenzene (HNAB) with RDX, β-HMX, BCHMX and ε-CL-20 have been prepared. Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), Raman studies and differential thermal analysis (DTA) have confirmed that this process leads to the formation of co-crystals (CCs), in which HMX is present in its δ-form, CL-20 in its β-form and trans-HNS changes its conformation to cis-form. In most cases, these significant structural changes and intermolecular-orientations have improved the impact sensitivities, mainly in some CACs with cis-HNS; for CL-20, on the other hand, the insertion of HNS or HNAB into its crystal lattice is destabilizing. Logical relationships between some FTIR, Raman vibrational modes of the CACs studied and parameters of their initiation and detonation have shown greater information about corresponding molecular structural relationships. The detonation energies of these co-crystals are in most of cases higher than that of correspond to the percentage of the coformers in them. It has been shown that this co-agglomeration can reduce the sensitivity of nitramines (with the exception of CL-20) roughly to the level of the sensitivity of analogous plastic-bonded explosives (PBXs), with the high-performance parameters of the resulting CACs being maintained. From a practical point of view, the combination of HMX and HNS appears to be the most optimal; these CACs at a molar ratio of 1.00/0.11 have exhibited the impact sensitivity of 47 J and the calculated detonation velocity 8.98 km.s−1.

Energetic characteristics of 1H-tetrazole/ NaClO4 ionic cocrystal

ABSTRACT The energetic characteristics of a novel ionic cocrystal composed of 1H-tetrazole/sodium perchlorate and differences of properties between the cocrystal and simple mixture are reported herein. Cocrystals containing reductants and oxidizers exhibit enhanced energy release rate compared with their simple mixture owing to their short molecular distances. Differential scanning calorimetry, thermogravimetric analysis, sensitivity tests and humidity tests are performed to clarify the properties of the cocrystals and simple mixture. The calculated detonation velocity of the cocrystal was higher than that of 1H-tetrazole. The cocrystal achieves high deflagration performance, as evaluated via a pressure vessel test.

An interesting 3D energetic metal - framework based Ag(I) ions and 3,4-diaminofurazan

ABSTRACT As a new structural motif, an interesting 3D energetic metal – framework of silver ions and 3,4-diaminofurazan, [Ag+(daf)NO3 −]n, is successfully synthesized and the structure is determined by single-crystal X-ray diffraction. The effects of hydrogen bond, coordination bond, adsorption and filling interactions make this compound have a high density (2.694 g·cm−3 at 293 K). The calculated detonation velocity and the sensitivities are all comparable with trinitrotoluene (TNT). The onset decomposition temperature is equal to hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), state-of-the-art explosive. This framework provides a potential superiority of E-MOFs for energetic materials.

Pressure-stabilized high-energy-density material YN10

Polynitrogen compounds have been intensively studied for potential applications as high energy density materials, especially in energy and military fields. Here, using the swarm intelligence algorithm in combination with first-principles calculations, we systematically explored the variable stoichiometries of yttrium–nitrogen compounds on the nitrogen-rich regime at high pressure, where a new stable phase of YN10 adopting I4/m symmetry was discovered at the pressure of 35 GPa and showed metallic character from the analysis of electronic properties. In YN10, all the nitrogen atoms were sp 2-hybridized in the form of N5 ring. Furthermore, the gravimetric and volumetric energy densities were estimated to be 3.05 kJ g−1 and 9.27 kJ cm−1 respectively. Particularly, the calculated detonation velocity and pressure of YN10 (12.0 km s−1, 82.7 GPa) was higher than that of TNT (6.9 km s−1, 19.0 GPa) and HMX (9.1 km s−1, 39.3 GPa), making it a potential candidate as a high-energy-density material.

1,5-Diaminotetrazole-4N-oxide (SYX-9): a new high-performing energetic material with a calculated detonation velocity over 10 km s−1

Highly-energetic 1,5-diaminotetrazole-4N-oxide (SYX-9) was synthesized and characterized physically, chemically, and energetically.

On the Question of the Energetic Performance of TKX‐50

AbstractAn analysis of the experimental data available to date shows that the explosive TKX‐50 has really high explosive performance characteristics, although not as outstanding as claimed previously, due to the overestimation of the enthalpy of formation. The obtained experimental data on the dependence of the detonation velocity on the density of TKX‐50 samples agree with the results of calculations, in which the experimentally determined enthalpy of formation 194.1 kJ mol−1 is used. The energetic performance of TKX‐50 surpasses the parameters of nitramines RDX, HMX, and even CL‐20, determined at the same densities. However, the calculated detonation velocity of TKX‐50 at theoretical maximum density is 9287 m s−1, which is slightly lower than the detonation velocity of CL‐20 at maximum density. It is worth noting that the detonation velocity of the TKX‐50 at the experimentally attainable density (1.8 g cm−3) is 9037 m s−1. Calculations using the experimentally determined enthalpy of formation show that high‐energy composite propellant formulations containing TKX‐50 are inferior in a specific impulse to compositions based on CL‐20 and HMX.

Nitropyrazole based tricyclic nitrogen-rich cation salts: A new class of promising insensitive energetic materials

Nitrogen-rich compound 5,5′-(4-nitro-1H-pyrazole-3,5-diyl)-bis-(4H-1,2,4-triazole-3,4-diamine) (4) and its energetic salts (5–8) were synthesized. Compounds 4–7 posesse satisfactory mechanical sensitivity (IS > 40 J, FS > 360 N). 4 and 5 have the higher decomposition temperatures (4, 318 °C and 5, 304 °C) than TNT (TNT, 295 °C). Compared with TATB (8114 m•s−1), the calculated detonation velocity of 8 (8716 m•s−1) has a certain advantage. Multi-factor analysis shows that these compounds are promising nitrogen-rich energetic materials.

Investigation of CL-20/TFAZ cocrystal: preparation, structure and performance

The cocrystals of hexanitrohexaazaisowurtzitane (CL-20) and 7H-trifurazano[3,4-b:3’,4’-f:3”,4”-d]azepine (TFAZ) in a 1 : 1 molar ratio were prepared by both slow evaporation and self-assembly method. Structure determination showed that it belongs to the monoclinic system (space group P21) with crystal density of 1.932 g cm−3. The intermolecular hydrogen bonds and N–O•••NO2 type interactions are demonstrated as the predominant driving force in cocrystal formation. Furthermore, the cocrystals were successfully synthesized by a self-assembly method using only water as solvent at mild conditions, and the product yield was up to 92.3%. The two types of cocrystals were fully characterized by powder X-ray diffraction and scanning electron microscope. Moreover, the thermal behavior, sensitivity, and calculated detonation performances of the cocrystal were evaluated. The cocrystal exhibits good thermal stability (Td = 242.8 °C), low impact sensitivity (H50 = 42 cm) and friction sensitivity (Pf = 38%), high crystal density, and high calculated detonation velocity (9103 m/s). This work opens up a new perspective in the environment-friendly preparation of energetic cocrystals on a large-scale, as well as provides a potential low-sensitivity and high-energy explosive.

Structure and Properties of 1,4‐Bis(Trinitromethyl)Benzene

AbstractThe structure, activation energy, onset temperature, heat of formation, and calculated detonation properties of 1,4‐bis(trinitromethly)benzene are reported here. The crystal structure of this compound shows that as other trinitromethyl containing compounds the planes of the three independent C‐NO2 are approximately perpendicular to one another. The crystal density is 1.805 g/cm3. Like other trinitromethyl containing explosives, the onset temperature is relatively low (103.7 °C). The incorporation of two trinitromethly groups yields a reasonable oxygen balance (−25.5 %) which is close to that of RDX (−21.6 %). While the calculated detonation velocity of HNX exceeds that of TNT it is almost 6 % lower than that of RDX.

Molecular dynamics simulation on TKX-50/fluoropolymer

Molecular dynamics were used to study dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) and TKX-50 based high-energy mixed explosives (HE) with fluoropolymers (F2311, F2314, F2611 and F2614). The binding energies, radial distribution functions, cohesive energy density (CED), mechanical properties and detonation properties have been simulated. The simulated results show that TKX-50 based HE-polymer formed by adding fluoropolymer to the (100) surface of TKX-50 has excellent thermodynamic stability, especially F2611 and F2614. The CED values of four HE-polymer are reduced by adding a small number of fluoropolymer, the order of CED is F2611 > F2311 ≈ F2614 > F2314. The calculated results show that the stiffness of four HE-polymer is weakened and the elasticity is enhanced, the order of mechanical properties of four HE-polymer is F2614 > F2314 > F2311 > F2611. The calculated detonation velocity (D) and detonation pressure (P) of four HE-polymers reduce a little, and still keep their high values. TKX-50 based HE-polymer of F2614 has better overall performances, which provides theoretical reference for the formulation of TKX-50 based HE-polymer.

Effect of ionic composition on thermal properties of energetic ionic liquids

A model to predict the effect of ionic composition on the thermal properties of energetic ionic liquids was developed by quantitative structure-property relationship modeling, which predicted the detonation velocity, pressure, and melting temperature of energetic ionic liquids. A hybrid approach was used to determine the optimal subset of descriptors by combining regression with the genetic algorithm as an optimization method. The model showed the high accuracy, reaching a correlation factor of R2 as 0.71, 0.73 and 0.68 for the correlation between the calculated detonation velocity, pressure and melting temperature against reported values. It was validated extensively and compared to the Kamlet–Jacobs equation. The effect of ion composition on the thermal properties of energetic ionic liquids could be quantitatively analyzed through the developed model, to give an insight for the design of new energetic ionic liquids.

Synthesis of 4,8‐Dinitraminodifurazano[3, 4‐b,e]pyrazine Derived Nitrogen‐Rich Salts as Potential Energetic Materials

AbstractA series of new energetic compounds based on 4,8‐dinitraminodifurazano[3, 4‐b,e]pyrazine were synthesised and fully characterized by NMR and IR spectroscopy, and elemental analysis. The structures of compounds 3‐a, 3‐c, 3‐f, and 3‐g were determined by single‐crystal X‐ray diffraction analysis. The physicochemical and energetic properties of these energetic compounds including density, thermal stability, and energetic performance (e. g., detonation velocities and detonation pressures) were investigated. The combination of nitrogen‐rich 4,8‐dihydrodifurazano[3, 4‐b,e]pyrazine framework with highly energetic nitramino moieties endowed these as‐synthesised compounds with excellent detonation performance. Among these as‐synthesised compounds, five energetic salts (3‐a, 3‐b, 3‐c, 3‐f, and 3‐g) exhibited satisfactory calculated detonation velocities (8921–9413 m s‐1), which were superior to cyclo‐1,3,5‐trimethylene‐2,4,6‐trinitamine (RDX) (8878 m s‐1). Notably, compound 3‐f exhibits an excellent calculated detonation velocity of 9166 m s‐1 and also acceptable impact and friction sensitivities (IS=8 J, FS=108 N). The prominent detonation performance with moderate sensitivities indicates that compound 3‐f has the potential to compete with traditional high explosives.

Synthesis, characterization, and thermal analysis of a new energetic salt based on 1ʹ-hydroxy-1H,1ʹH-5,5ʹ-bitetrazol-1-olate

ABSTRACT4-Amino-1,2,4-triazolium 1ʹ-hydroxy-1H,1ʹH-5,5ʹ-bitetrazol-1-olate (ATHBTO) was synthesized by reacting 4-amino-1,2,4-triazole (AT) and 1H,1′H-5,5′-bistetrazole-1,1′-diolate dihydrate (H2BTO·2H2O). Its crystal structure was characterized through single-crystal X-ray diffraction. Meanwhile, FTIR, 1H NMR, 13C NMR, and elemental analysis were also introduced to analyze its composition. The thermal stability was investigated by differential scanning calorimetry, thermogravimetric analysis, and thermogravimetric tandem infrared spectrum. Results indicated that ATHBTO exhibited excellent resistance to thermal decompositions reaching 511.4 K and had a 64.6% mass loss between 475.7 and 552.3 K. The kinetics parameters were calculated by Kissinger’s method and Ozawa–Doyle’s method. Moreover, according to the Kamlet–Jacobs formula, the calculated detonation velocity and detonation pressure of ATHBTO attained 8218 m/s and 28.69 GPa, respectively.

1D Energetic Metal-Organic Framework: Sodium 6-Nitro-5-oxidopyrazolo[3,4-c][1,2,5]oxadiazol-4-ide with Good Thermal Stability

A ladder-like 1D energetic metal-organic framework, sodium 6-nitro-5-oxidopyrazolo[3,4-c][1,2,5]oxadiazol-4-ide was first synthesized from the potassium salt. The sodium salt with an interesting furazan-pyrazole system which is first synthesized by an intramolecular condensation, is fully characterized by crystal X-ray diffraction, elemental analysis, IR spectroscopy. The sodium salt shows a density of 1.88 g cm−3, a high decomposition temperature of 258 oC, and a promising calculated detonation velocity of 7760 m s−1. It has an impact sensitivity of 16 J which makes it a replacement as a thermally stable energetic material. Besides, the natural compound 6-nitro-4H-pyrazolo[3,4-c][1,2,5]oxadiazole 5-oxide shows the best energetic properties with calculated detonation velocity of 9407 m s−1 and calculated detonation pressure of 40.4 GPa.

(E)‐1,2‐Bis(3,5‐dinitro‐1H‐pyrazol‐4‐yl)diazene – Its 3D Potassium Metal–Organic Framework and Organic Salts with Super‐Heat‐Resistant Properties

(E)‐1,2‐Bis(3,5‐dinitro‐1H‐pyrazol‐4‐yl)diazene (H2NPA, 1) and its energetic salts, which are a series of new, energetic, highly heat‐resistant, dense explosives, were synthesized. The explosives contain four nitro groups and an azo‐bridged framework and were characterized by 1H and 13C NMR (in some cases 15N NMR) spectroscopy, IR spectroscopy, and elemental analysis. The crystal structures of K2NPA (a three‐dimensional metal–organic framework, 3D MOF) and the guanidinium salt 4 were determined by single‐crystal X‐ray diffraction, and their properties (density, thermal stability, and sensitivity towards impact and friction) were investigated. The detonation properties were evaluated from the measured density and calculated heat of formation by the EXPLO5 v6.01 program. All of the salts exhibit thermal stabilities with decomposition temperatures ranging from 156 to 315 °C, high densities (1.70–2.15 g cm–3), high detonation velocities (8224–9083 m s–1), and high positive heats of formation (45.7–1040.1 kJ mol–1). The obtained 3D metal–organic framework explosive K2NPA combines exceptional thermal stability (Td = 315 °C) with a high density (d = 2.15 g cm–3) and possesses ideal calculated detonation velocity (vD = 8275 m s–1) and pressure (PCJ = 31.1 GPa) values. Moreover, its suitable impact sensitivity (IS) of 1.5 J and friction sensitivity (FS) of 60 N make K2NPA an outstanding, highly heat‐resistant, green primary explosive. The guanidinium salt 4 also exhibits a high thermal stability (Td = 304 °C) that is superior to that of HMX, insensitivity to impact (IS > 40 J) and friction (FS > 360 N) comparable to those of 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB), and a high detonation performance (vD = 8391 m s–1).

Theoretical study of the reaction kinetics and the detonation wave profile for 1,3,5-triamino-2,4,6-trinitrobenzene

We simulate the reaction process of 1,3,5-triamino-2,4,6-trinitrobenzene in wide temperature and pressure ranges by molecular dynamics and evaluate the intermediate molecules, chemical reaction rates, and Hugoniot relations. Based on them, the leading shock wave, fast reaction zone, Chapman-Jouguet state, and slow reaction zone under detonation are investigated by different theoretical methods. A complete structure of the detonation wave is obtained. The calculated detonation velocity, detonation pressure, detonation products, and the length of the reaction zone are in agreement with the experiments and others' calculations. We find that some intermediate molecules play an important role in determining the reaction path of explosives but just remain a little after detonation, such as H2 and NH3.