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1

Effect of Natural Ageing on the Safety Parameters and Performance of TNT-based Melt Cast RDX/TNT Compositions

Sharma Tirupati Chander, Singh Arjun, Soni Pramod Kumar, Singh Vasundhara, Kishore Prateek

Central European Journal of Energetic Materials

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2023

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Vol. 20, no. 2

138--158

EN

2,4,6-Trinitrotoluene (TNT) based melt cast RDX/TNT compositions stockpiled for a period of time were exposed under natural environmental conditions, with humidity and temperature for storage in the range of 40-95% RH and 4-47 °C, respectively. The composition, chemical, thermal and mechanical properties of the RDX/TNT compositions before and after ageing were studied by high performance liquid chromatography, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry and a universal test machine, respectively. In addition, the safety, mechanical sensitivities, detonation velocity and blast parameters were also investigated through vacuum stability tests (VST), a BAM fall hammer apparatus, a BAM friction tester and a piezoelectric accelerator, respectively. The results showed that after ageing, the colour of the composition had become dark but there was no variation in the RDX and TNT content by high performance liquid chromatography (HPLC). The VST results showed that the volume of evolved gas was almost the same and less than 2 mL/g, indicating chemical stability. The results obtained from different analytical techniques demonstrated that there was no significant variation in the chemical, thermal and mechanical properties for the aged samples as compared to the fresh composition. The change in mechanical sensitivity is related to the components and the ageing mode. The detonation velocity and detonation pressure were found to be similar to those of the freshly prepared composition and consistent with the data obtained from overall natural ageing. The results of blast studies revealed that there was either a similar or slight variation in the blast peak over pressure and impulse for RDX/TNT compositions at different locations before and after ageing under natural environmental conditions.

2

Three Insensitive Energetic Co-crystals of 1-Nitronaphthalene, with 2,4,6-Trinitrotoluene (TNT), 2,4,6-Trinitrophenol (Picric Acid) and D-Mannitol Hexanitrate (MHN)

Hong D., Li Y., Zhu S., Zhang L., Pang C.

Central European Journal of Energetic Materials

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2015

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Vol. 12, no. 1

47--62

EN

Co-crystallization is proposed as an effective method to alter the physicochemical properties of energetic materials, e.g. density, sensitivity and solubility. As reported in this paper, it was found that 1-nitronaphthalene could form cocrystals with TNT, picric acid and MHN in a 1:1 molecular ratio. The sensitivity and thermal stability of the 1-nitronaphthalene co-crystals was greatly improved compared with that of pure TNT, picric acid and MHN. In addition, the melting points of TNT, picric acid and MHN were lowered through co-crystallization with 1-nitronaphthalene. The electrostatic potential surface of 1-nitronaphthalene, calculated by the DFT method, showed that the electron-rich 1-nitronaphthalene has a tendency to be a proton donor and to co-crystallize with other energetic materials. The structures of the co-crystals of 1-nitronaphthalene with TNT and picric acid were characterized by single crystal X-ray diffraction (SXRD). The 1-nitronaphthalene/MHN co-crystal was studied by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and FTIR.

3

New Synthetic Methods for 4,4’,5,5’-Tetranitro-2,2’-bi- 1H-imidazole (TNBI)

Szala M., Lewczuk R.

Central European Journal of Energetic Materials

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2015

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Vol. 12, no. 2

261--270

EN

Four new nitration methods for the synthesis of 4,4’,5,5’-tetranitro-2,2’- bi-1H-imidazole (TNBI) were examined. TNBI was synthesized by nitration of 2,2’-bi-imidazole (BI) with the following mixtures: (CH3CO)2O/HNO3, (CF3CO)2O/ HNO3, P4O10/HNO3 and H3PO4/P4O10/HNO3. Nitration of BI with a mixture of nitric acid and acetic anhydride leads to 4,4’-dinitro-bi-imidazole. The other nitrating conditions investigated gave TNBI in lower yields (6.0-22.4%). Crystallization of crude TNBI from wet ethanol/acetone gave TNBI as its dihydrate. The structures of BI and TNBI were characterized by 1H, 13C and 15N NMR spectroscopy and elemental analysis. Friction and impact sensitivity, detonability and detonation velocity were determined for pure TNBI dihydrate.

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

Nowoczesne materiały wybuchowe : trzecia generacja

Zygmunt B.

Wiadomości Chemiczne

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2007

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[Z] 61, 11-12

913-935

EN

Explosives are chemical compounds or mixtures which, under the influence of an external energetic stimulus of sufficient intensity, develop a rapid exothermic reaction generating large quantity of gas at very high pressure and temperature. Explosives are a chemical energy source of high power (quantity of energy released in a time unit) and high density (quantity of energy per unit of volume). From the application point of view, explosives are divided into blasting, propelling and initiating ones. Of these, blasting explosives are the most common and their production worldwide reaches many millions of tons a year. Detonation is the basic form of their explosive transformation. It can be started by a relatively intense energetic stimulus, for example by a disruptive or other detonator. The linear velocity of propagation of explosive's chemical decomposition during detonation (detonation velocity) reaches several thousand meters per second. During detonation of a blasting explosive, the pressure of detonation products reaches the level of several GPa for mining explosives and as much as 50 GPa for the most powerful military explosives. The detonation pressure value is the measure of an explosive's brisance. It is the brisance that is used to destroy (crush) the structure of a medium. Due to the fast development of mining industry, the demand for effective, safe and inexpensive mining explosives was growing. In the mid-fifties of the 20th century new types of blasting explo-sives appeared on the US market without typical explosive material as part of the composition. The materials were a mixture of ammonium nitrate as oxidant (base ingredient) and an organic or inorganic combustible ingredient. Within a short time, ammonium nitrate fuel oil (ANFO), a mixture of granulated ammonium nitrate and fuel oil characterized by a good flow handy in use, became the most widely used material. Nowadays, ANFO makes more than half of all explosives used in the mining industry worldwide. Simultaneously, another revolutionary innovation was introduced - substantial quantity of water, previously regarded as an ingredient that ruined the explosive properties of mixtures, was purposefully added to the explosive composition. The resulting slurry and emulsion explosives containing a saturated water solution of ammonium nitrate had a semi-liquid consistency, which made it possible to mechanise their manufacture and to load boreholes with explosives on the mining site. The author has specified new, safe varieties of explosives which do not contain typical explosive compounds, with ammonium nitrate as a predominant ingredient. They are named "third generation explosives", the first generation being black gunpowder used for a millennium as the versatile explosive and the second generation being explosive chemical compounds (mostly nitrocompounds, aromatic nitroamines and the esters of nitric acid(V) and aliphatic polyalcohols). In Poland, a research on new varieties of third generation explosives was started in the early 1970s at IPO (ammonium nitrate type) and at WAT (slurry and emulsion type). Based on the research, several modern versions of explosives were developed and brought into production to be used subsequently in the country's open and underground pits. The paper presents the basic historical developments in the field of mining explosives, from black gunpowder to modern safe materials devoid of explosive constituents. Based on the author's own research, the physical and chemical properties of third generation explosives have been characterized in depth, such as ANFO, slurries and emulsions. Particular attention has been paid to the physical structure of mixtures, which plays a key role in determining their explosive characteristics. Keywords: mining high explosives, history of development, explosive properties.

6

Problemy wodorowego paliwa

Marzec A.

Polityka Energetyczna

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2007

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T. 10, z. 1

89-96

PL

Współczesne procesy produkcji wodoru z paliw kopalnych lub wody związane są z emisją dwutlenku węgla, wobec czego należy je skojarzyć z wydzielaniem i depozycją C02. Jeśli tak się stanie, powstanie problem konkurencyjności pomiędzy energią elektryczną -także wytwarzaną w skojarzeniu z depozycją- a wodorem. Transport wodoru od producenta do użytkownika wymaga nowych technologicznych rozwiązań w zakresie przesyłu i dystrybucji oraz szczególnie starannego zapewnienia bezpieczeństwa z uwagi na szeroki zakres wybuchowości i palności tego gazu. Obecnie wodór nie jest w stanie konkurować z przesyłem energii elektrycznej. Zastosowanie wodoni do napędu silników w transporcie samochodowym to przede wszystkim dotąd nierozwiązany problem zaopatrzenia samochodów w taką ilość wodoru, która umożliwi pojazdom uzyskanie podobnego zasięgu (po jednorazowym tankowaniu), jaki charakteryzuje samochody o napędzie węglowodorowym. Tego rodzaju bariery nie występują w sektorze transportu samochodowego, w którym stosowany byłby napęd hybrydowy (napęd paliwami węglowodorowymi współpracujący naprzemiennie z napędem elektrycznym). Stan zaawansowania nowych rozwiązań w zakresie produkcji i szerokiego zastosowania wodoru jako paliwa rokuje nadzieje na osiągnięcie dojrzałości nie wcześniej niż po 30-40 latach, tymczasem ochrona klimatu wymaga szybkiego działania.

EN

Contemporary processes producing hydrogen from fossil fiiels or water, contribute to carbon dioxide emission. Thus, they have to be associated with capture and seąuestration of carbon dioxide. If so, eiectricity energy that can be also combined with C02 removal, on one side and hydrogen fuel on the other side. should be compared in a number of issues. The hydrogen large scalę transfer from a manufacturer to end-users requires new technological solutions and ensuring extremely careful safety measiires due to the wide explosive rangę of hydrogen and its high flammability. It is elear that at present, hydrogen transfer cannot compete with eiectricity transfer. Use of engines powered by hydrogen in transportation sector, poses yet unsolved problem of hydrogen storage in cars. Neither compressed, nor liquefied hydrogen might be a good solution. A compression as well as liquefaction reąuires high energy input. Practical hydrogen storage demands a major technology breakthrough, most likely in solid-state materials capable of storing a sufficient amount of hydrogen. Such barriers would not oceur in transportation sector powered by hybrid engines (hydrocarbon fuel drive engine working alternately with electrical motor). Summing up, the technological breakthrough of production and large scalę use of hydrogen could be expected after 30 up to 40 years. However, climate protection is immediately needed.

7

1,1-diamino-2,2 dinitroeten (DADNE), nowy wysokoenergetyczny i małowrażliwy materiał wybuchowy

Cudziło S., Chyłek Z.

Wiadomości Chemiczne

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2006

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[Z] 60, 11-12

763-791

EN

The search for new molecules that combine possibly high performance and simultaneously low sensitivity is one of the directions of development of explosives. In 1998, 1,1-diamino-2,2-dinitroethene (DADNE) was synthesized by N. Latypov et al. using destructive nitration of heterocyclic compounds containing the structural element of acetamidine. Soon it turned out that this comparatively simple structure, which can be synthesized without difficulties, possesses very favorable functional qualities as an explosive. The structure of DADNE molecule is conducive to creation of inter- and intramolecular hydrogen bonds, and this makes DADNE a very stable (activation energy of 243 kJ/mole), thermally resistant (decomposition above 200oC) and dense substance (1.787 g/cm3). DADNE has favorable oxygen balance and on decomposition the molecule can produce entirely gaseous products (CO, H2O, N2) in the amount of ca. 900 cm3/g. Consequently the performance of DADNE almost equals to the common high explosive RDX (1,3,5-triaza-1,3,5-trinitrocyclohexane), but its sensitivity is comparable with that of TNT (2,4,6-trinitrotoluene). Other advantages of DADNE include excellent compatibility with typical components of explosive formulations and propellants as well as ability to be pressed into mechanically resistant pellets without any additives. The already known properties of DADNE indicate that it can be used on its own or in formulations as a high explosive or propellant component.

8

Self-sensitizable Characteristics of Modified Ammonium Nitrate

Ye Z., Qian H., Lu Ch., Liu Z.

Central European Journal of Energetic Materials

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2005

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Vol. 2, nr 4

55-62

EN

Ammonium nitrate has been modified by evaporative recrystallization from its mixture solution with hexadecyl trimethyl ammonium bromide and sodium dodecyl sulfate. The physical property of the modified compound has been nwestigated by SEM, DSC, specific surface area and particle size measurements. The results show that in comparation with common ammonium nitrate, the modified ammonium nitrate has an irregular crystal shape, greater specific surface area, better particle size distribution, lower heat of crystal pattern transition and higher transition temperaturę. These indicate the modified ammonium nitrate has a mesoporous structure with good self-sensitizable, anti-hygroscopic and anticaking performances as an oxidizer of industrial explosive.