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1

Effect of Nanomaterials on Thermal Stability of 1,3,6,8-Tetranitro Carbazole

Pourmortazavi S. M., Rahimi-Nasrabadi M., Rai H., Jabbarzadeh Y., Javidan A.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 1

201--216

EN

1,3,6,8-tetranitro carbazole (TNC) as a secondary explosive is used in composite explosive formulations in order to reduce the sensitivity and increase the stability of the explosive composites. In this work, the thermal stabilities of pure TNC and its nanocomposites prepared via three different nanoparticles were studied by thermal analysis, i.e. differential scanning calorimetery (DSC) and thermogravimetry (TG) techniques. Thermal analysis data revealed that the thermal behavior of pure TNC is significantly different from the nanocomposites studied. Pure TNC decomposed completely during a single step in the temperature range 385-425 °C. However, the addition of nanoparticles to the TNC powder leads to higher thermal stability in comparison with the pure TNC. The decomposition kinetics of TNC and its nanocomposites were studied by non-isothermal DSC at several heating rates. Thermokinetic and thermodynamic parameters corresponding to the thermal decomposition of pure TNC and nanocomposites were computed and compared. The results showed that the addition of nanoparticles to the TNC powder has a considerable effect on the thermal stability of the explosive.

2

Characterization and Application of Al/Ni Reactive Multilayers in Exploding Foils

Wang T., Zeng Q., Li M.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 3

547--558

EN

A self-propagating reaction achieved by initiating an Al/Ni reactive multilayer foil can generate significant heat. The interdiffusion rate of the reactants plays an important role in the foils properties and is mainly affected by premixing and the bilayer thickness. The present research aims to characterize Al/Ni multilayer foils and to investigate their influence on an exploding foil initiator. Samples with different bilayer thicknesses were fabricated by magnetron sputtering. The heat released and the flame velocity were characterized. Foils with a stored energy of about 1100 J/g were prepared and the heat released revealed the existence of a 4 nm premixing layer. The analytical model proposed by Mann was employed to match the measured flame velocities; the fitted model showed good agreement with the experimental results. To make a comparison, Cu and Al/Ni exploding foils with the same bridge size were fabricated and tested in the identical discharge circuit. The results showed that the energy deposition ratio of an Al/Ni foil was 67-69%, while the value for Cu was only 39-45%, which indicated that Al/Ni multilayers could effectively increase the energy utilization of an initiator. Larger average flyer velocities were also observed with the Al/Ni initiators.

3

N-Nitropyridinium Nitrate: An Efficient Nitrating Agent for the Synthesis of 2-[Butyl(nitro)amino]ethyl Nitrate (n-BuNENA)

Bayat Y., Esmailmarandi F.

Central European Journal of Energetic Materials

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2016

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Vol. 13, no. 4

838--844

EN

The present investigation focused on the synthesis of 2-[butyl(nitro)amino]ethyl nitrate (n-BuNENA), by the nitration of N-butylethanolamine. For this purpose, various nitrating agents were studied and N-nitropyridinium nitrate was found to be a good nitrating agent. Short reaction time, ease of handling, performance of the reaction in one step and good yield are the main aspects of the present method. It also lead to 75% yield, which is a higher yield than by other methods. The purity of the product was evaluated by HPLC analysis, and its identity was confirmed by IR and 1H NMR spectroscopy.

4

Thermal Expansion of Explosive Molecular Crystals: Anisotropy and Molecular Stacking

Qian W., Zhang C., Xiong Y., Zong H., Zhang W., Shu Y.

Central European Journal of Energetic Materials

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2014

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Vol. 11, no. 1

59--81

EN

Molecular dynamics simulations of three typical explosive crystals, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), 1,1-diamino-2,2- dinitroethene (FOX-7) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), were carried out under NPT ensemble and selected force field. The equilibrium structures at elevated temperatures were obtained, which show that the stacking behaviour of the molecules does not change with temperature. The coefficient of thermal expansion (CTE) values were calculated by linear fitting methods, and the results show that the CTE values are close to the experimental results and are anisotropic. The total energies of the cells expanding along each single crystallographic axis were calculated by the periodic density functional theory method, indicating that the energy change rates are anisotropic, and correlation equations of the energy change vs. CTE values were established. The essence of the anisotropy of the explosive crystal’s thermal expansion was compared and elucidated.

5

Synthesis, Crystal Structure, and Properties of a Novel, Highly Sensitive Energetic, Coordination Compound: Iron (II) Carbohydrazide Perchlorate

Liu R., Zhou Z., Qi S., Yang L., Wu B., Huang H., Zhang T.

Central European Journal of Energetic Materials

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2013

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Vol. 10, no. 1

17--36

EN

A single crystal of iron (II) carbohydrazide perchlorate [FeII (CHZ)3](ClO4)2 (FeCP), a novel, lead-free, energetic coordination compound, was synthesized and its structure determined by X-ray single crystal diffraction for the frst time. The crystal belongs to the monoclinic system P2(1)/n space group, with a = 1.0066(2) nm, b = 0.8458(2) nm, c = 2.1194(4) nm, β = 100.693(3)° and Z = 4. The central Fe(II) ion is coordinated to three bidentate carbohydrazide units through the carbonyl oxygen atom and an amino nitrogen atom, forming a six-coordinated, non-centrosymmetric complex cation. The thermal analyses by differential scanning calorimetry and thermogravimetry show that the onset temperature of thermal decomposition (152.7 °C) and the critical temperature of thermal explosion of FeCP (161.2 °C) are both much lower than those of other transition metal carbohydrazide perchlorate compounds, and also those of some other primary explosives in service. FeCP has a high enthalpy of combustion, as measured by oxygen bomb calorimetry. The impact, friction and fame sensitivity tests indicate that FeCP is extremely sensitive and hazardous. Unexpected explosions occurred even during the operational processes. In order to explore the intrinsic cause of these explosions, theoretical calculations of the orbital energies were performed based on DTF. These results reveal that the impact sensitivity is positively correlated with the energy gap between HOMO and LUMO: the smaller energy gap results in the higher impact sensitivity.

6

Role of Thermochemical Decomposition in Energetic Material Initiation Sensitivity and Explosive Performance

Shackelford S. A.

Central European Journal of Energetic Materials

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2008

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Vol. 5, nr 1

75-101

EN

Catastrophic initiation of an energetic material consists of a complex, interactive, sequential train of mechanistic mechanical, physical, and chemical processes which occur over a finite time period and proceed from macroscopic into sub-microscopic composition levels (bulk > crystalline > molecular > atomic). Initiation results when these processes proceed at a rate which generates sufficient energy (heat) to reach a threshold stage within this finite time period. Thus, the rate at which these mechanistic processes occur defines initiation sensitivity and affects performance. Thermochemical decomposition processes regulate the rate at which heat energy is released at the molecular level, and therefore to some extent, control energetic material initiation sensitivity and performance characteristics. Kinetic deuterium isotope effect (KDIE) data, obtained during the ambient pressure thermochemical decomposition process, identifies the mechanistic rate-controlling bond rupture which ultimately regulates the energy release rate of a given energetic material. This same rate-controlling bond rupture also appears as a significant rate-limiting feature in higher order deflagration, combustion, and explosion phenomena. The effect the KDIE-determined rate-controlling bond rupture exerts on initiation sensitivity, and its potential influence in combustion and explosion performance is delineated.

7

Synthesis and Characterisation of 2,2-Dinitro-1,3-propanediol-based Plasticisers

Ek S., Eldsäter C., Goede P., Holmgren E., Tryman R., Latypov N. V., Raymond Y. G. Y., Wang L. Y.

Central European Journal of Energetic Materials

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2005

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Vol. 2, nr 4

33-45

EN

In this paper, the synthesis of two energetic plasticisers (2,2-dinitro-1,3-bis(2-azido acetoxy) propane and 2,2-dinitro-1 ,3-bis(formyloxy)propane is outlined. The attempted syntheses of even further derivatives are described. The prepared compounds were characterised and evaluated as plasticisers. Their glass transition temperatures are acceptable to excellent, but both of them are thermally unstable.