The effect of LaFeO3@MnO2 on the thermal behavior of energetic compounds: An efficient catalyst with core-shell structure

Large particle size and low specific surface area are two major factors of restricting metal oxides as combustion catalyst with high performance. The construction of three-dimensional (3D) heterojunction materials with synergistic effect is conducive to enhancing the catalytic activity. In this work, LaFeO₃ were prepared by a facile solvo-thermal method and post-heat treament. However, the LaFeO₃ with a large particle size shows poor specific surface area, resulting in a low catalytic activity. In order to improve its catalytic activity, a 3D core/shell heterostructured LaFeO₃@MnO₂ composite was constructed by coupling LaFeO₃ with MnO₂. The core-shell structured LaFeO₃@MnO₂ provides a larger specific surface area and high catalytic effect on the thermal decomposition of ammonium perchlorate (AP) with a reduced decomposition temperature from 403.73 °C to 281.38 °C, an enhanced energy release from 649.6 J·g⁻¹ to 966.5 J·g⁻¹, and a decreased apparent activation energy from 139.05 kJ·mol⁻¹ to 110.88 kJ·mol⁻¹. Additionally, LaFeO₃@MnO₂ also shows efficient catalytic effects on the thermal decomposition of hexanitrohexaazaisowurzitane (CL-20) and cyclotetramethylenetetranitramine (HMX)_.     

Prediction of the condensed phase heat of formation of energetic compounds

A new reliable simple model is presented for estimating the condensed phase heat of formation of important classes of energetic compounds including polynitro arene, polynitro heteroarene, acyclic and cyclic nitramine, nitrate ester and nitroaliphatic compounds. For CHNO energetic compounds, elemental compositions as well as increasing and decreasing energy content parameters are used in the new method. The novel correlation is tested for 192 organic compounds containing complex molecular structures with at least one nitro, nitramine or nitrate energetic functional groups. This work improves the predictive ability of previous empirical correlations for a wide range of energetic compounds. For those energetic compounds where group additivity method can be applied and outputs of quantum mechanical computations were available, it is shown that the root mean square (rms) deviation of the new method is lower.     

Characterisation of elastomers fracture behavior by energetic parameters

The knowledge of fracture behavior of elastomers necessitates the comprehension of crack initiation and propagation phenomena which pose difficulties related to the deformation of elastomers. The reliability of elastomer materials is linked to their resistance to rupture. This resistance can be evaluated using the global approach of fracture mechanics. The objective of this work is to numerically analyze by finite element method the characterization of rupture behavior of these materials on the basis of energetic parameters. Consideration is given to the evolution of the deformation energy density to quantify the energy of tear of a real material identified by hyper-elastic material models.     

Important aspects of behaviour of organic energetic compounds: a review

The importance of a prediction tool increases with greater relevance for synthesis, performance and vulnerability predictions. Some important aspects of performance behaviour and their theoretical calculations, which are indispensable in recognising energetic molecules of interest, are described here. This review also discusses on factors influencing sensitivity and overall stabilities of organic energetic compounds especially on nitroaromatics and nitramines, and exceptions to this relationship suggest other factors playing roles in specific instances.     

Studies on energetic compounds. Part XI: preparation and thermolysis of polynitro organic compounds.

The thermolysis of high energetic polynitro organic compounds has been reviewed in the present communication.     

Supercritical fluid extraction of energetic nitroaromatic compounds and their degradation products in soil samples

This paper explores the use of supercritical fluid extraction (SFE), in combination with various analyte collection strategies, for extracting energetic nitroaromatic compounds and their degradation products from soil samples. The required selectivity has been achieved by a combination of an SFE program and active trapping. Several different collection strategies were tested, using a selection of liquids (methanol, toluene, methyl tert-butyl ether, acetonitrile), inert and solid-phase extraction materials (Nexus, Oasis, LiChrolut), and 1-cm liquid chromatography precolumns (porous graphitic carbon, PGC). The best results were obtained using SFE in combination with a PGC precolumn. This setup allows on-line cleanup of the extract, and comparable results were obtained using either GC-ECD or GC-chemical ionization-MS for confirmatory analysis. The time required for a complete analysis was less than 60 min, and only 1 mL of toluene was needed for a 0.5-g representative sample. In contrast, the EPA standard method 8330 required 18-h sonication and 20 mL of acetonitrile for a 4.0-g sample and further time for sample cleanup and HPLC analysis. The method presented here provides method detection limits in the low-nanogram range, with relative standard deviations lower than 7%. The optimized method has been compared and validated with EPA method 8330 in terms of efficiency parameters such as robustness, accuracy (trueness and precision), and capability of detection. The validation demonstrated that the two analytical methodologies give comparable performance for the determination of nitroaromatic compounds, but SFE is superior for analyzing amine degradation products.     

Quick estimation of heats of detonation of aromatic energetic compounds from structural parameters

In this paper, a simple procedure is introduced for a quick and reliable estimation of detonation heats of aromatic energetic compounds without considering heats of formation of energetic compounds. This method does not use any experimental or computed data of energetic materials. The methodology assumes that the heat of detonation of an energetic compound with composition of C(a)H(b)N(c)O(d) can be obtained from the number of nitrogens, ratios of oxygen to carbon and hydrogen to oxygen as well as the contribution of some specific functional groups. There is no need to use any assumed decomposition products to calculate heats of detonation for energetic compounds. Predicted heats of detonation of pure energetic compounds with the product H(2)O in the liquid state for 31 aromatic energetic compounds have a root mean square (rms) of deviation of 0.32 kJ/g from experiment. The new method gives good results with respect to two empirical methods which use measured heats of formation of explosives with two sets of decomposition gases.     

A simple correlation for predicting heats of fusion of nitroaromatic carbocyclic energetic compounds

In this paper, it is shown that heats of fusion of nitroaromatic carbocyclic energetic compounds can be predicted by using some structural parameters. Elemental composition and the contribution of some specific polar functional groups would be needed in the new method. Predicted heats of fusion using the method described herein for 41 nitroaromatic carbocyclic compounds are compared with experimental data. Calculated heats of fusion have a root mean square (rms) deviation of 3.01 kJ/mol and average deviation of 2.35 kJ/mol for these energetic compounds.     

Determining heats of detonation of non-aromatic energetic compounds without considering their heats of formation

A new procedure is introduced for calculating heats of detonation of non-aromatic energetic compounds through ratios of oxygen to carbon and hydrogen to oxygen as well as the contribution of some structural parameters. There is no need to use heats of formation of non-aromatic energetic compounds that are usually needed by the other methods. Moreover, this much simple method does not use any experimental and computed data of energetic materials. Predicted heats of detonation for 28 non-aromatic energetic compounds have a root mean square (rms) of deviation of 0.54 kJ/g from experiment, which show good agreement with respect to measured values. The new method is the simplest procedure for predicting heats of detonation and provides reliable results which are comparable with the other methods.     

Theoretical prediction of electric spark sensitivity of nitroaromatic energetic compounds based on molecular structure

A new simple correlation is introduced for predicting electric spark sensitivity of nitroaromatic compounds. This approach is based on the number of carbons and hydrogens as well as the ratio of hydrogens to oxygens and the presence of certain groups, i.e. alkyl or alkoxy groups, attached to an aromatic ring. The model is optimized using a set of 17 polynitroaromatic explosives as training set and then it is applied to 14 explosives from a variety of chemical families as test set in order to assess the predictive capability of new method. Predicted results are reasonably close to the measured values for both training and test sets.     

Development of a miniature calorimeter for identification and detection of explosives and other energetic compounds

The development of versatile systems capable of providing rapid, portable, and inexpensive detection of explosives and energetic compounds are critically needed to offer enhanced levels of protection against current and future threats to homeland security, as well as satisfying a wide range of applications in the fields of forensic analysis, emergency response, and industrial hazards analysis. Calorimetric techniques have been largely overlooked in efforts to develop advanced chemical analysis technology, largely because of limitations associated with the physical size of the instruments and the relatively long timescales (>30 min) required to obtain a result. This miniaturized calorimeter circumvents these limitations, thereby creating a first-of-its-kind system allowing thermal analysis to be performed in a portable format that can be configured for use in a variety of field operations with a significantly reduced response time (approximately 2 min). Unlike current explosives detectors, this system is based on calorimetric techniques that are inherently capable of providing direct measurements of energy release potential and therefore do not depend on prior knowledge of familiar compounds.     

Studies on energetic compounds Part 45. Synthesis and crystal structure of disodium azotetrazole pentahydrate

A disodium salt of azotetrazolate (SAZ) has been prepared and characterized by elemental, UV, 13C NMR, FT-IR, and crystallographic analyses. Single crystals of the pentahydrate were grown by slow evaporation of an aqueous solution under reduced pressure. The crystal structure of SAZ has been determined by X-ray diffraction. The crystal lattice is triclinic P1 (no. 2) with lattice parameters a=7.115(1)A, b=7.559(1)A, c=12.025(1)A, alpha=79.75(1) degrees , beta=81.12(1) degrees , gamma=68.16(1) degrees and V=587.97(12)A3. Explosion delay studies have been undertaken using the tube furnace technique. The thermal stability of the compound has been discussed in the light of TG-DSC and explosion delay.     

Desorption of Solid O2 Induced by Vibrational Excitations

Molecular dynamics calculations of the vibrationally induced desorption of a simple low cohesive energy molecular solid, O ₂ have been carried out. The calculations were extended up to 8 ns after the excitation. The desorption process has been found to have an evaporative character. Upon high excitation densities, guest molecules dissolved in the lattice were carried off by the matrix material. The evolution of the bulk of the irradiated material was examined. The transfer of vibrational energy into lattice heating evolves from a steady linear to rapid nonlinear regime. The efficiency of energy transfer to the lattice was found to depend nonlinearly on the density of excited molecules and on the anharmonicity of the intramolecular potential.     

Electrical behavior of lithium intercalated layered In-Se compounds

InSe and In₂Se₃ was lithium intercalated by mean of a spontaneous intercalation reaction. The electrical conductivity was studied and was found to be altered by 3-orders of magnitude with respect to non-intercalated samples. An interesting time dependent anisotropy appeared during intercalation, associed to the initial non-uniform Li distribution and the movement of Li concentration kinks.     

Approximate prediction of melting point of nitramines, nitrate esters, nitrate salts and nitroaliphatics energetic compounds

A simple new procedure is introduced to predict melting point of selected class of energetic compounds containing nitramines, nitrate esters, nitrate salts and nitroaliphatics energetic compounds. The number of nitrogen and oxygen as well as the number of nitramine group and the contribution of some specific functional groups would be needed in the new method. Energetic compounds should contain at least one of the functional groups including N-NO(2), C-ONO(2) or nonaromatic C-NO(2). Calculated melting point for 33 nitramines, nitrate esters, nitrate salt and nitroaliphatics are compared with experimental data. Predicted melting points have average deviation of 5.4% for these energetic compounds.