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Svatopluk Zeman - One of the best experts on this subject based on the ideXlab platform.
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A new look on the electric spark sensitivity of Nitramines
Defence Technology, 2020Co-Authors: Svatopluk ZemanAbstract:Abstract Electric spark energy, EES, for a 50% probability of initiation of the 14 Nitramines was determined using a measuring instrument in which the electrodes are in direct contact with the sample. Indirectly proportional relationships were established between the logarithm of the EES values and the length of the longest N–N bond in the Nitramine molecule. This finding is compatible with the mechanism of the first step in the electro-reduction of the Nitramine grouping. Directly proportional relationships were found to exist between the EES values and the crystal lattice free volumes, ΔV (i.e. an increase in the ΔV values increases the Nitramine's resistance to electric sparks) but there were several Nitramines with the opposite course of this relationship. Also a semilogarithic relationships between the EES values and a ratio of intrinsic volumes of molecule, Vint, to the ΔV values were described as well as ambiguous linear dependence between these energies and a sum of the positive and negative extremes of the molecular surface electrostatic potentials, VS,Σ. Several Nitramines studied (always the same ones) display roughly the same distribution in the coordinate systems of relationships with lengths of the longest N–N bonds, the Vint/ΔV ratio and the sum VS,Σ as the independent variables. It was found that, typically, such relationships start from a single identical point, in effect a point corresponding to data for a structural unit from which the studied Nitramines can be hypothetically generated, and/or are converging on another point, often the one corresponding to the data for HNIW. All the findings point to a fundamental influence of the intermolecular forces on reactivity of Nitramines exposed to electric sparks.
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Crystal lattice free volume and thermal decomposition of Nitramines
Defence Technology, 2019Co-Authors: Svatopluk Zeman, Ahmed K. HusseinAbstract:Abstract The linear, directly proportional, equations between the Arrhenius parameters (Ea and log A) of the thermal decomposition and the crystal lattice free space per molecule, ΔV, of 22 Nitramines are described. It is shown that, because of a significant limitation by the molecular structural characteristics of such compounds, they are divided into a number of partial relationships. These partial relationships divide the Nitramines into a group of substances relating to dimethyl Nitramine and a sub-group related to e−HNIW. These directly proportional equations mean that an increase in the ΔV values is related to an increase in the thermal stability of the corresponding Nitramines. A comparison with similar published dependencies for the impact and friction sensitivities, on the one hand, and with the relationship between the Ea values and the sum of the negative and positive extremes of molecular surface electrostatic potentials, on the other, confirms the well-known fact that intermolecular interaction in the Nitramines studied plays a decisive role in the thermal reactivity of such compounds. The crystal lattice free space manifests itself here perhaps only in the solid state thermal decomposition of RDX, HMX and DINGU. This study again confirms a level of disorder in the distribution of the forces in the crystal lattice of the “common” quality of e−HNIW, compared with its “reduced sensitivity (RS)” or pure analogues.
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New Aspects of the Impact Reactivity of Nitramines
Propellants Explosives Pyrotechnics, 2000Co-Authors: Svatopluk ZemanAbstract:The impact reactivity (“the first reaction”) of 16 Nitramines was determined as the drop energy Ed, required for 50% initiation probability. Relationships have been found between the Ed values, on the one hand, and heats of fusion, 15N NMR chemical shifts of aza atoms in reaction centers, parameters of low-temperature thermolysis, and oxygen balances of Nitramines studied, on the other. Taking these relationships the Ed values were predicted for four Nitramines, from which three have not been synthesized yet. On the basis of the said relationships it was stated that the impact reactivity of Nitramine molecules depends on the electronic configuration within their reaction centers and on their conformational stability and intensity of their intermolecular interactions. The reaction centers here are the same as in the case of initiation of the Nitramines by shock. It is found that ϵ-HNIW possesses higher thermal and impact reactivities in comparing with those of β-modification. Neue Aspekte der Schlagempfindlichkeit von Nitraminen Die Schlagempfindlichkeit (“die erste Reaktion”) von 16 Nitraminen wurde als die Fallenergie Ed bestimmt, die fur eine 50% ige Initiie_rungswahrscheinlichkeit erforderlich ist. Es wurden Beziehungen zwischen den Ed-Werten einerseits und den Bildungswarmen, den 15N NMR chemischen Verschiebungen der aza-Atome in Reaktionszentren, Parametern der Niedertemperaturthermolyse und der Sauerstoffbilanz der untersuchten Nitramine andererseits gefunden. Unter Benutzung dieser Beziehungen wurden die Ed-Werte von 4 Nitraminen vorhergesagt, von denen 3 noch nicht synthetisiert sind. Basierend auf den besagten Relationen wird festgestellt, das die Schlag_empfindlichkeit von Nitraminmolekulen von der Elektronenkonfiguration innerhalb ihrer Reaktionszentren, ihrer Kon_for_ma_tions_stabilitat und der Intensitat der intermolekularen Wechselwirkung abhangt. Die Reaktionszentren hier sind dieselben wie im Falle der Schockinitiierung der Nitramine. Es zeigte sich, das ϵ-HNIW eine hohere thermische Empfindlichkeit sowie Schlagempfindlichkeit im Vergleich mit der β-Modifikation besitzt. Nouveaux aspects de la sensibilite a l'impact des Nitramines La sensibilite a l'impact (“la premiere reaction”) de 16 Nitramines a ete determinee comme etant l'energie de chute Ed necessaire pour obtenir une probabilite d'initiation de 50%. On a trouve des relations entre les valeurs Ed, d'une part, et les chaleurs de fusion, les deplacements des raies RMN 15N des groupes aza dans les centres de reaction, les parametres de la thermolyse a basse temperature et le bilan d'oxygene des Nitramines etudiees, d'autre part. En utilisant ces relations, on a predit les valeurs Ed de 4 Nitramines, dont 3 ne sont pas encore synthetisees. Sur la base des relations susnommees, on constate que la sensibilite a l'impact des molecules de Nitramine depend de la configuration electronique a l'interieur de leurs centres de reaction, de leur stabilite conformationnelle et de l'intensite de leur interaction intermoleculaire. Les centres de reaction sont ici les memes que dans le cas de l'initiation des Nitramines par choc. On a montre que ϵ-HNIW possedait une sensibilite thermique ainsi qu'une sensiblite a l'impact superieures a celles obtenues avec la modification β.
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relationship between the arrhenius parameters of the low temperature thermolysis and the 13c and 15n chemical shifts of Nitramines
Thermochimica Acta, 1992Co-Authors: Svatopluk ZemanAbstract:Abstract A linear relationship is shown to exist between the Arrhenius parameters E and log A of the initial stage of the non-autocatalysed, low-temperature thermolysis and the 13C and 15N chemical shifts of six Nitramines. The existence of this relationship is interpreted from the point of view of the primary fragmentation in the thermolysis of the Nitramines, i.e. homolysis of the N-NO2 bond. A linear relationship is also found between the heat of explosion (represented as the square of the detonation velocity and the 15N chemical shift of the nitro groups of four of the Nitramines and as well as the 13C chemical shift in the derivatives with the methylene-Nitramine grouping within their molecules.
Do Binh Minh - One of the best experts on this subject based on the ideXlab platform.
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simultaneous degradation of 2 4 6 trinitrophenyl n methylNitramine tetryl and hexahydro 1 3 5 trinitro 1 3 5 triazine rdx in polluted wastewater using some advanced oxidation processes
Journal of Industrial and Engineering Chemistry, 2014Co-Authors: Do Ngoc Khue, Nguyen Van Chat, Vu Quang Bach, Do Binh MinhAbstract:Abstract Here we report the study on the utilization of several advanced oxidation processes such as electro-oxidation and Fenton process in simultaneous treatment of two Nitramine explosives: 2,4,6-trinitrophenyl-N-metylNitramine (Tetryl) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The preliminary tests indicated that the electrolytic method using a TiO 2 /IrO 2 /RuO 2 -coated electrode could rapidly degrade Tetryl but not RDX. While the addition of certain amount of H 2 O 2 induced an increase of Tetryl degradation yield but had insignificant effect on RDX decomposition, the use of Fenton's reagent showed an enhanced efficiency in degradation of both Nitramines. It can be concluded that among tested processes, Fenton process is the most effective for treatment of Nitramine-containing wastewaters.
William A Goddard - One of the best experts on this subject based on the ideXlab platform.
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A detailed model for the decomposition of Nitramines: RDX and HMX
Journal of Computer-Aided Materials Design, 2001Co-Authors: Debashis Chakraborty, Richard P Muller, Siddharth Dasgupta, William A GoddardAbstract:A unified decomposition scheme for two very important cyclic Nitramines used as primary explosives – RDX and HMX – has been constructed using ab initio Density Functional Theory (DFT) calculations. Molecular parameters such as vibrational frequencies and moments of inertia corresponding to the computed potential energy profile of unimolecular decomposition of these Nitramines were then used to obtain the thermochemistry of all identified species and reaction rate constants of each individual channel. These primary decomposition reactions were then combined with: (i) important secondary reactions of the key reactive radical intermediates, such as CH_2NNO_2 (Methylene Nitramine MN), CH_2N, NO, NO_2, OH, etc.; (ii) existing nitramie reaction networks [33]. We have developed an improved mechanism for the detailed chemistry of Nitramines which can be applied to combustion and detonation phenomena of this class of energetic materials.
Mohammad Hossein Keshavarz - One of the best experts on this subject based on the ideXlab platform.
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A New Method for Predicting the Friction Sensitivity of Nitramines
Central European Journal of Energetic Materials, 2020Co-Authors: Mohammad Hossein Keshavarz, M. Hayati, Sara Ghariban-lavasani, Narges ZohariAbstract:This study presents a new simple correlation between friction sensitivity of Nitramines and their molecular structures. This novel correlation can help chemists and chemical engineers to predict the friction sensitivity of new Nitramines without using any experimental data, which is important for safety in industrial processes. The new correlation can also help to elucidate the mechanism of initiation of energetic materials by frictional stimuli. This new method assumes that friction sensitivity of a Nitramine of general formula CaHbNcOd can be expressed as a function of the optimized elemental composition and the contributions of specific molecular structural parameters. The new correlation has root mean square and average deviations of 7.64 and 6.44 J, respectively, for 20 Nitramines with different molecular structures. The proposed new method was also tested for 11 Nitramines containing complex molecular structures.
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Correlation between shock sensitivity of Nitramine energetic compounds based on small-scale gap test and their electric spark sensitivity
Zeitschrift für anorganische und allgemeine Chemie, 2017Co-Authors: Mohammad Hossein Keshavarz, Mohammad Ghaffarzadeh, Mohammad Reza Omidkhah, Kiumars FarhadiAbstract:Electric spark sensitivity and shock sensitivity based small-scale gap test for Nitramine energetic compounds are two important sensitivity parameters, which are needed for assessment of their safety in working places. A novel method is introduced for reliable prediction of electric spark or shock sensitivity of a desired Nitramine energetic compound when reliable data for one of the sensitivity is available. A novel correlation with a high value of correlation coefficient (R2=0.998) is derived between electric spark and shock sensitivities of 20 cyclic and acyclic Nitramines. For these Nitramines, the predicted results of electric spark sensitivities of the novel model are compared with two of the best available models. The root-mean-square (rms) and maximum deviations of the new model are 0.20 and 0.51 J, respectively, which are much less than two comparative methods. The reliability of the new method for prediction of electric spark sensitivity of further 14 Nitramines is also compared with one of the best available methods, where the measured electric spark or shock sensitivities were not available in literature.
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Relationship between electric spark sensitivity and activation energy of the thermal decomposition of Nitramines for safety measures in industrial processes
Journal of Loss Prevention in The Process Industries, 2013Co-Authors: Mohammad Hossein Keshavarz, Narges Zohari, Seyed Abolfazl SeyedsadjadiAbstract:Abstract This study presents a new simple correlation between electric spark sensitivity of Nitramines and their activation energies of thermolysis, which are important for safety measures in industrial processes. The new correlation can help to elucidate the mechanism of initiation of energetic materials by electric spark. It can be used to predict the magnitude of electric spark sensitivity of new Nitramines, which is difficult to measure. The methodology assumes that electric spark sensitivity of a Nitramine with general formula C a H b N c O d can be expressed as a function of its activation energy of thermal decomposition as well as optimized elemental composition and the contribution of specific molecular structural parameters. The new correlation has the root mean square and the average deviations of 1.37 and 1.09 J, respectively, for 21 Nitramines with different molecular structures. The proposed new method is also tested for 16 Nitramines so that there is no experimental data of electrostatic sensitivity for them.
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Simple method for prediction of activation energies of the thermal decomposition of Nitramines
Journal of Hazardous Materials, 2009Co-Authors: Mohammad Hossein KeshavarzAbstract:Abstract A novel general method has been introduced to predict activation energies of thermal decomposition of Nitramines as an important class of energetic compounds. It is shown that the activation energies of acyclic Nitramines can be expressed as a function of optimized elemental composition. The resultant relationship as a core correlation can be corrected for cyclic Nitramines that contain more than five member ring. R 2 value or the coefficient of determination of the new correlation is 0.94. The new correlation has the root mean square (rms) and the average deviations of 5.67 and 3.98 kJ/mol, respectively, for 14 Nitramines with different molecular structures. The new method is also tested for some cyclic and acyclic Nitramines with complex molecular structures, e.g. two new Nitramines 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW) and 4,10-dinitro-2,4,6-tetroxa-4,10-diaazaisowurtzitane (TEX), so that it can predict relatively good results as compared to the experimental values.
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Reliable prediction of electric spark sensitivity of Nitramines: a general correlation with detonation pressure.
Journal of hazardous materials, 2009Co-Authors: Mohammad Hossein Keshavarz, Hamid Reza Pouretedal, Abolfazl SemnaniAbstract:For Nitramines, a general correlation has been introduced to predict electric spark sensitivity through detonation pressure. New method uses maximum obtainable detonation pressure as a fundamental relation so that it can be corrected for some Nitramines which have some specific molecular structure. There is no need to use crystal density and heat of formation of Nitramine explosives for predicting detonation pressure and electric spark sensitivity. The predicted electric spark sensitivities are compared with calculated results on the basis of quantum mechanical computations for some Nitramines that latter can be applied. The root mean square (rms) deviations from experiment for new method and the predicted results of complicated quantum mechanical method are 1.18 and 3.49J, respectively.
Andy M Booth - One of the best experts on this subject based on the ideXlab platform.
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preliminary studies into the environmental fate of nitrosamine and Nitramine compounds in aquatic systems
Energy Procedia, 2013Co-Authors: Lisbet Sorensen, Eirik F Da Silva, Odd Gunnar Brakstad, Kolbjorn Zahlsen, Andy M BoothAbstract:Preliminary hydrolysis and photolysis data are presented for a suite of Nitramines and nitrosamines relevant to post combustion CO2 capture using monoethanolamine solvent. Two Nitramines (DMNA and MEA-NO2) and the nitrosamine NDELA were resistant to hydrolytic degradation at pH 4, 7 and 9. The nitrosamine NPz was hydrolytically stable at pH 4 and 9, but exhibited ~30% degradation at pH 7. Nitrosamines appear highly susceptible to photolytic degradation, while Nitramines are photolytically stable. The data form part of an ongoing study investigating the fate of nitrosamines and Nitramines in terrestrial and aquatic environments.