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1

Performance and Detonation Characteristics of Polyurethane Matrix Bonded Attractive Nitramines

Elbeih A., Wafy T. Z., Elshenawy T.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 1

77--89

EN

Several cast-cured plastic bonded explosives (PBXs) based on cyclic nitramines bonded by a polyurethane matrix have been prepared and studied. The nitramines were ε-CL20 (ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, ε-HNIW), BCHMX (bicyclo-HMX, cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole), RDX (1,3,5-trinitro-1,3,5-triazacyclohexane) and HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane). The detonation velocities were measured experimentally. The brisance of the prepared compositions was determined by the Kast method. The penetration performance of shaped charges filled with the prepared compositions was measured experimentally. The detonation parameters of the studied compositions and the individual explosives were calculated using the EXPLO5 thermodynamic code. It was concluded that CL20-HTPB has the highest detonation characteristics and performance of all of the prepared PBXs. BCHMX-HTPB is an interesting PBX with performance and detonation characteristics higher than those of RDX-HTPB. A linear relationship between the detonation pressures of the prepared PBXs and their performances in terms of the explosive brisance was observed; while the penetration depths formed by the shaped charge jets depended on the Gurney velocity of the studied PBXs samples.

2

Thermally Induced Polymorphic Transformation of Hexanitrohexaazaisowurtzitane (HNIW) Investigated by in-situ X-ray Powder Diffraction

Liu Y., Li S., Wang Z., Xu J., Sun J., Huang H.

Central European Journal of Energetic Materials

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2016

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Vol. 13, no. 4

1023--1037

EN

The ε→γ phase transition of HNIW induced by heat was investigated with in situ X-ray powder diffraction (PXRD). The effects of purity, particle size, insensitive additives and the time of isothermal heat treatment on the phase transition were evaluated. It was found that the phase transition is irreversible with changes in temperature, and the two phases can coexist in a certain temperature range. Moreover, the initial phase transition temperature increases with increasing purity and decreasing particle size of HNIW, and thus with the approximate crystal density. The addition of graphite and paraffin wax to HNIW as insensitive additives leads to a decrease in the initial phase transition temperature, but the addition of TATB does not affect the initial phase transition temperature. Thus, TATB is a suitable insensitive additive. Moreover, at the critical temperature, the isothermal time determined the efficiency of the ε- to γ-phase transition. This work lays the foundations for the choice of molding technologies, performance test methods, ammunition storage options, as well as the manufacture of HNIW-based explosive formulations.

3

Statistical Optimization of the Preparation of HNIW Nanoparticles via Oil in Water Microemulsions

Bayat Y., Zarandi M., Khadiv-Parsi P., Salimi Beni A.

Central European Journal of Energetic Materials

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2015

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Vol. 12, no. 3

459--472

EN

HNIW (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) is a family member of high-energy density cage nitramines which have so many versatile applications. In this paper, HNIW nanoparticles were prepared by the oil in water microemulsion route. The effects of various experimental parameters on this reaction were investigated using the Taguchi method. The effects of different variables: organic phase, water/organic phase (W1/W2), organic phase/ propanol (W3/W4) and HNIW weight percent, on the particle size of the HNIW were investigated at three distinct levels. Optimal conditions for obtaining HNIW nanoparticles were determined. Performing the process under the optimal conditions proposed by the Taguchi method leads to the production of HNIW nanoparticles with an average size of about 80 nm. The HNIW nanoparticles were characterized using Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), Differential Thermal Analysis (DTA) and X-Ray Diffraction (XRD).

4

Metody syntezy i właściwości fizykochemiczne 2,4,6,8,10,12-heksanitro-2,4,6,8,10,12-heksaazaizowurcytanu (HNIW)

Borkowski J., Czerwińska M.

Wiadomości Chemiczne

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2013

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[Z] 67, 1-2

93--109

EN

Explosives have a very rich history of its creation. This history dates back to the ninth century, when the Chinese invented a black powder. In the end of the twentieth century, the first nitroamine polycyclic cage structure was obtained. The representative of this group is 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaizowurtzitane (HNIW, Cl-20). HNIW has recently been the subject of an interest as one of the strongest explosive material. As nitroamine, HNIW is compared to the other energetic materials: RDX i HMX [1, 2]. Researchers [5, 6] showed, that it is possible to replace a variety of typical explosives by HNIW and thanks to that obtain compositions with higher densities, heat of explosion and higher velocity of detonation. In the published papers [7-13, 16] there were presented six polymorphs of HNIW: αβγδε with specific stabilities and structural characteristics. Unfortunately, there is no a direct method of obtaining HNIW. There are at least four steps needed to obtain HNIW. The first step is the synthesis of HBIW [20-22]. The next one is debenzylation reaction of HBIW [20-29] in order to remove the benzyl groups. The third step is removal of the two other benzyl groups and replace them by nitroso, formyl or acetyl groups [20, 24, 30, 32]. In the final step there is a nitration of HNIW precursors [31-37]. The HNIW seems to be a promising explosive and it can replace other currently used energetic materials. However, using HNIW is limited due to the complicated and expensive technology of its production. Therefore, research groups carried out new syntheses of HNIW to eliminated these problem. In this article, review of the literature on the physicochemical properties and synthetic methods for HNIW were presented. The basic physical and explosive parameters of HNIW were summarized. The spatial structure was presented and polymorphs of HNIW were characterized. The methods for obtaining HNIW and intermediate products needed for its preparation were described. The methods of preparation of different HNIW polymorphs were also given.

5

Effect of Different Polymeric Matrices on the Sensitivity and Performance of Interesting Cyclic Nitramines

Elbeih A., Zeman S., Jungova M., Akstein Z.

Central European Journal of Energetic Materials

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2012

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Vol. 9, nr 2

131-138

EN

Different polymeric matrices, based on butadiene-styrene rubber, polymethyl-methacrylate and silicone binders, were investigated for their ability to decrease the sensitivity of explosives to different mechanical stimuli. A series of plastic explosives based on four different nitramines, namely RDX (1,3,5-trinitro- 1,3,5-triazacyclohexane), β-HMX (β-1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane), BCHMX (bicycloHMX, cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5- d ]imidazole) and ε -HNIW (ε -2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, ε-CL-20), bonded by the selected polymeric matrices were prepared. Sensitivity to impact of all of the plastic explosives prepared as well as of the pure explosives, was measured using the fall hammer test. Sensitivity to friction was determined using the BAM friction test. The performance was studied using the ballistic mortar test and the results were recorded relative to TNT (trinitrotoluene) as reference. By comparing the results of impact and friction sensitivities, it is obvious that the mechanism of transfer of the friction force to the reaction center of the nitramine molecule should be different from that of impact energy transfer. The silicone binder appeared to be the best polymer for decreasing the sensitivity of explosives. The results of the ballistic mortar proved that the performance of the plastic explosives prepared is affected by the type and weight percentage of the binder in each sample.

6

Path to ε-HNIW with Reduced Impact Sensitivity

Elbeih A., Husarova A., Zeman S.

Central European Journal of Energetic Materials

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2011

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Vol. 8, nr 3

173-182

EN

New purification method was applied to obtain epsilon HNIW (ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, ε-HNIW) which has low impact sensitivity. The method is based on removing the impurities from a solution of alpha HNIW (ε-HNIW) by a chemical reaction to obtain pure epsilon form. For comparison, selected different published methods for recrystallization of HNIW to obtain the epsilon form were studied. All the selected methods are based on solvent-antisolvent technique. The optimum parameters, such as type of solvent and anti-solvent, volume ratio of solvent to anti-solvent, rate of addition, speed of stirring, etc., were applied to enhance the crystal size and shape of ε-HNIW. Checking the polymorphs of the obtained HNIW was done by Fourier transform infrared spectroscopy (FTIR). The thermal stability of the prepared samples was studied by using differential thermal analysis technique (DTA). Qualitative analysis of the crystal size and shape was done using scanning electron microscope (SEM) devise. Quantitative measurement of the crystals sizes for the studied samples was determined by Laser scattering particle size distribution analyzer. Impact sensitivity was measured by falling hammer test. The results indicate that all the applied methods of recrystallization give ε-HNIW. The impact sensitivity of HNIW decreases by obtaining small particles with regular shape. All the used published methods produce ε-HNIW with higher impact sensitivity than other nitramines. While the obtained crystals from the new method has regular smooth surface, with small particle size and its impact sensitivity is lower than RDX and HMX.

7

Thermal Stability and Detonation Characteristics of Pressed and Elastic Explosives on the Basis of Selected Cyclic Nitramines

Elbeih A., Pachmáň J., Zeman S., Trzciński W. A., Akstein Z., Sućeska M.

Central European Journal of Energetic Materials

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2010

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Vol. 7, nr 3

217-232

EN

Bicyclo-HM X (cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d] imidazole or BCHM X) was studied as a plastic explosive bonded with the C4 matrix and with Viton A. Also a series of nitramines namely RDX (1,3,5-trinitro-1,3,5=triazinane), HM X (1,3,5,7-tetranitro-1,3,5,7-tetrazocane) and HNIW (ĺ-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, ĺ-CL-20) were studied for comparison with the same types of binders. The detonation velocity, D, of all prepared mixtures was measured. Their thermal stability was determined using non-isothermal differential thermal analysis (DTA). While the C4 matrix lowers the thermal stability of the resulting explosives, Viton A enhances this stability. Approximate relationships between the peaks of exothermic decomposition and the D values were found. The detonation parameters were also calculated by means of Kamlet & Jacobs method, CHEETAH and improved EXPLO5 code for all the mixtures. From the measured D values and the calculated detonation parameters, it is obvious that the detonation parameters of BCHM X-mixtures are very close to HM X-explosives and better than those of RDX-mixtures. It was found that the C4 matrix reduces the difference between the values of energy of detonation in the studied C4 mixtures. As expected, the pressed HNIW-Viton A mixture has the highest detonation parameters of all of the prepared mixtures.

8

Research of High Explosives Based on RDX, HMX and CL-20 in the Small Scale Underwater Test Examination

Koślik P., Staś J., Wilk Z., Zakrzewski A.

Central European Journal of Energetic Materials

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2007

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Vol. 4, nr 3

3-13

EN

HNIW(CL-20), HMX and RDX have been examined in the small scale underwater test. Pressure curves of detonating materials were obtained. The comparison between HNIW, HMX and RDX pressure waves parameters were estimated. Applicability of the small scale underwater test for high explosives examining became proved.