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Novel High-Nitrogen Content Energetic Compounds with High Detonation and Combustion Performance for use in Plastic Bonded Explosives (PBXs) and Composite Solid Propellants

Keshavarz M. H., Abadi Y. H., Esmaeilpour K., Damiri S., Oftadeh M.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 2

364--375

EN

Five novel high-nitrogen content (N>50%) derivatives of tetrazole are introduced in the study reported here. The assessment of various properties of these compounds were performed, which include physicothermal properties (crystal density, condensed phase heat of formation, melting point, enthalpy of fusion and entropy of fusion), detonation performance (velocity and pressure of detonation, detonation temperature and power), sensitivity with respect to external stimuli (impact, shock, friction and electric spark) and combustion performance (specific impulse). The predicted results of these compounds are compared with dihydroxylammonium 5,5’-bistetrazole-1,1’-diolate (TKX-50) and octanitro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) as a high performance ionic salt and a neutral explosive, respectively. The novel energetic compounds were found to have higher detonation and combustion performance than either TKX-50 or HMX. The new explosives are therefore good candidates to obtain high detonation and combustion performance in plastic bonded explosives (PBXs) and composite solid propellants, respectively.

2

Modelling of the Effect of Concentrated Nitration Conditions on the Efficiency of the Production of ,7-Dinitro-1,3,5,7-tetraazabicyclo[3,3,1]nonane (DPT)

Hadi Z., Esmaeilpour K., Damiri S., Afzali A., Keshavarz M. H.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 1

72--84

EN

3,7-Dinitro-1,3,5,7-tetraazabicyclo[3,3,1]nonane (DPT) is one of the most important intermediates in the synthesis of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). A suitably modified Bachmann process, nitrolysis of solid hexamine in the presence of ammonium nitrate-nitric acid and acetic anhydride on a laboratory scale, is introduced to increase the efficiency, production capacity and purity of the DPT produced. Various quantitative and qualitative analytical methods were used for the identification and quality control of the product. A central composite design (CCD) of experiments was used to optimize the production process, increasing the production capacity, reducing the amount of acetic acid as the reaction medium to a suitable limit, and examining the effects of the main factors impacting on the efficiency of the nitration, e.g. the volume of ammonium nitrate-nitric acid solution, nitration temperature reactor addition time and volume of acetic anhydride. The overall results indicated that DPT was obtained with an efficiency of 64.58% and a production capacity of 20.77 (100 g·mL−1).

3

Statistical Optimization and Selective Separation of RDX and HMX Explosives by Using Binary Solvent Mixtures Containing Ethyl Acetate and Water

Damiri S., Pouretedal H. R., Panahi H., Dris A.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 2

391--402

EN

The present study introduces the application of a binary solvent of ethyl acetate and water for the selective separation of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). The effect of temperature and weight percent of ethyl acetate in water on the solubility of RDX and HMX over a temperature range of 273.15 K to 363.15 K and 70.0 wt.% to 100.0 wt.% ethyl acetate in water mixtures were modelled and optimized using a central composite design (CCD) and response surface methodology (RSM) in Minitab (ver. 16) software. Multiple regression analysis and analysis of variance (ANOVA) showed that the predicted results were in good agreement with the experimental data. The enthalpies of dissolution and mixing of the materials were determined experimentally from the solubility data. The experimental results showed that the solubility ratio of RDX to HMX can change 6.53- to 16.55-fold, indicating a much lower solubility of HMX in this binary solvent, for a relatively selective separation of RDX and HMX mixtures. Separation experiments under optimized conditions showed that 98.3% of the RDX impurity in HMX was recovered in the first precipitation with an HMX purity of > 99.5% as characterized by high performance liquid chromatography (HPLC).

4

A Novel Method for the Prediction of the Impact Sensitivity of Quaternary Ammonium-based Energetic Ionic Liquids

Keshavarz M. H., Esmaeilpour K., Khoshandam H., Keshavarz Z., Atabak H. H., Damiri S., Afzali A.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 3

520--533

EN

Impact sensitivity is an important safety parameter for the assessment of the hazards of working with new energetic compounds including ionic molecular energetic materials. This paper introduces two novel simple correlations to assess the impact sensitivity of quaternary ammonium-based energetic ionic liquids, which are based on the elemental composition of cations and anions divided by the molecular weight of a desired ionic liquid as well as the contribution of specific cations and anions. For 72 ionic molecular systems as a training set, the root mean square (rms) deviations of predictions for these models relative to experiment are 11 J and 6 J, respectively. The reliability of the models has also been tested for a further three ionic compounds containing complex structures, which give rms deviations of 12 J and 6 J, respectively, with respect to the measured data. The results of the current study indicate that the accuracy of this novel method for the prediction of the impact sensitivity of quaternary ammonium-based energetic ionic liquids is not necessarily enhanced by greater complexity.

5

Increasing the Efficiency of the Production of 1,3,5,7-Tetranitro-1,3,5,7-tetrazocane (HMX)

Afzali A., Esmaeilpour K., Damiri S., Hadi Z., Keshavarz M. H.

Central European Journal of Energetic Materials

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2016

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Vol. 13, no. 4

845--858

EN

This work introduces a suitable method for the optimization of selective synthesis of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX), as one of the most well-known high explosives, from the aspects of production capacity and efficiency, by nitration of 3,7-dinitro-1,3,5,7-tetraazabicyclo[3,3,1]nonane (DPT). The effective factors in the productive capacity of HMX and the synthesis of a product from raw DPT with high capacity, purity, and efficiency have been identified. The required qualitative and quantitative analyses were performed for the identification and confirmation of the product quality. In order to optimize the process of increasing the capacity of HMX production and evaluation of the effects of different factors on the production capacity, a series of experiments were designed and performed by using central composite design (CCD). Practical studies and statistical analyses showed good conformity between the model presented and the actual results, allowing the selective production of HMX with an efficiency of greater than 70% and a high production capacity.

6

Non-isothermal Studies on the Thermal Decomposition of C4 Explosive Using the TG/DTA Technique

Pouretedal H. R., Damiri S., Ghaemi E. F.

Central European Journal of Energetic Materials

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2014

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Vol. 11, no. 3

405--416

EN

The thermal behaviour of energetic materials is very important for their safe production, storage, handling and even demilitarization. In this work, the thermal behaviour and decomposition kinetics of conventional C4 plastic explosive has been studied experimentally by a non-isothermal thermogravimetric (TG)/differential thermal analysis (DTA) technique at different heating rates (2, 4, 6 and 8 °C·min-1). The kinetic triplet of activation energy, frequency factor and model of thermal decomposition of this compound has been evaluated via model-fitting and model-free methods. The results show a single thermal decomposition process for C4, with the model of integral function (g(α)) of [(1−α)-1/3 −1]2 and differential function (f(α)) of [(1−α)2/3(3α−3)/2(1−α)1/3−2], indicating a 3-dimensional diffusion mechanism. In addition, Ea values of 207.1 ± 17.3, and 241 kJ·mol-1, by using the isoconversional model-free modified Kissinger-Akahira-Sunose (KAS) and the Kissinger method, respectively, were obtained for the conversion interval of 0.3-0.7. The C4 matrix shows a significant effect on the activation energy distribution of pure RDX.