M.B. Talawar

Environmentally compatible next generation green energetic materials (GEMs).

This paper briefly reviews the literature work reported on the environmentally compatible green energetic materials (GEMs) for defence and space applications. Currently, great emphasis is laid in the field of high-energy materials (HEMs) to increase the environmental stewardship along with the deliverance of improved performance. This emphasis is especially strong in the areas of energetic materials, weapon development, processing, and disposal operations. Therefore, efforts are on to develop energetic materials systems under the broad concept of green energetic materials (GEMs) in different schools all over the globe. The GEMs program initiated globally by different schools addresses these challenges and establishes the framework for advances in energetic materials processing and production that promote compliance with environmental regulations. This review also briefs the principles of green chemistry pertaining to HEMs, followed by the work carried out globally on environmentally compatible green energetic materials and allied ingredients.

New directions in the science and technology of advanced sheet explosive formulations and the key energetic materials used in the processing of sheet explosives: Emerging trends.

This review presents the work carried out by the international community in the area of sheet explosive formulations and its applications in various systems. The sheet explosive is also named as PBXs and is a composite material in which solid explosive particles like RDX, HMX or PETN are dispersed in a polymeric matrix, forms a flexible material that can be rolled/cut into sheet form which can be applied to any complex contour. The designed sheet explosive must possess characteristic properties such as flexible, cuttable, water proof, easily initiable, and safe handling. The sheet explosives are being used for protecting tanks (ERA), light combat vehicle and futuristic infantry carrier vehicle from different attacking war heads etc. Besides, sheet explosives find wide applications in demolition of bridges, ships, cutting and metal cladding. This review also covers the aspects such as risks and hazard analysis during the processing of sheet explosive formulations, effect of ageing on sheet explosives, detection and analysis of sheet explosive ingredients and the R&D efforts of Indian researchers in the development of sheet explosive formulations. To the best of our knowledge, there has been no review article published in the literature in the area of sheet explosives.

Synthesis, characterization and evaluation of 1,2-bis(2,4,6-trinitrophenyl) hydrazine: A key precursor for the synthesis of high performance energetic materials

1,2-Bis(2,4,6-trinitrophenyl) hydrazine (3) is one of the precursors in the synthesis of an important energetic material viz., hexanitrazobenzene. The simple and convenient lab scale synthesis of title compound (3) was carried out by the condensation of picryl chloride (2) with hydrazine hydrate at 30-50 degrees C in methanol based on the lines of scanty literature reports. Picryl chloride was synthesized by the reaction of picric acid (1) with phosphorous oxychloride based on the lines of reported method. The synthesized compound (3) was characterized by IR and 1H NMR spectral data. Some of the energetic properties of the synthesized compound have also been studied. The theoretically computed energetic properties of the title compound (3) indicated the superior performance in comparison to tetranitrodibenzo tetraazapentalene (TACOT) and hexanitrostilbene (HNS) in terms of velocity of detonation.

Computer code to predict the heat of explosion of high energy materials

The computational approach to the thermochemical changes involved in the process of explosion of a high energy materials (HEMs) vis-à-vis its molecular structure aids a HEMs chemist/engineers to predict the important thermodynamic parameters such as heat of explosion of the HEMs. Such a computer-aided design will be useful in predicting the performance of a given HEM as well as in conceiving futuristic high energy molecules that have significant potential in the field of explosives and propellants. The software code viz., LOTUSES developed by authors predicts various characteristics of HEMs such as explosion products including balanced explosion reactions, density of HEMs, velocity of detonation, CJ pressure, etc. The new computational approach described in this paper allows the prediction of heat of explosion (DeltaH(e)) without any experimental data for different HEMs, which are comparable with experimental results reported in literature. The new algorithm which does not require any complex input parameter is incorporated in LOTUSES (version 1.5) and the results are presented in this paper. The linear regression analysis of all data point yields the correlation coefficient R(2)=0.9721 with a linear equation y=0.9262x+101.45. The correlation coefficient value 0.9721 reveals that the computed values are in good agreement with experimental values and useful for rapid hazard assessment of energetic materials.

Transition metal salts of 2, 4, 6-trinitroanilinobenzoic acid - potential energetic ballistic modifiers for propellants

Abstract Iron (Fe2+ and Fe3+), cobalt and nickel salts of 2,4,6-trinitroanilino benzoic acid have been synthesized, and characterized by elemental analysis, IR, metal content and explosive properties like impact and friction sensitivity. Differential thermal analysis shows the thermal stability of these salts as: ferrous, 270°C; ferric, 280°C; cobalt, 270°C; and nickel, 300°C. The impact sensitivity (h50%) of these salts are > 170 cm except for Fe3+ salt (156 cm). The friction sensitivity of all the salts were found to be > 36 kg. The salts were found to be devoid of any free acid present in them.

Probing the compatibility of energetic binder poly-glycidyl nitrate with energetic plasticizers: thermal, rheological and DFT studies

The essential idea of developing energetic binders and plasticizers is to enhance the thermal stability and energy content, improve the oxygen balance and burning behaviour of moulds, reduce the glass transition temperature and improve other mechanical properties of propellant and explosives formulations. The compatibility of energetic binder poly-glycidyl nitrate (PGN) with some energetic plasticizers of solid propellants was studied using differential scanning calorimetry (DSC), rheology and DFT methods in relation to the effect of the addition of five different energetic plasticizers, i.e. bis(2,2-dinitro propyl) acetal (BDNPA), dinitro-diaza-alkanes (DNDA-57), 1,2,4-butanetriol trinitrate (BTTN), N-N-butyl-N′(2-nitroxy-ethyl) nitramine (BuNENA) and diethyleneglycol dinitrate (DEGDN), on the rheological and thermal properties of the energetic binder PGN. The results obtained for the mixture of plasticizer and binder with respect to decomposition temperature (Tmax) and the format of the peak are compared with the results obtained for the pure binder, indicating the compatibility of these plasticizers with PGN. The glass transition temperatures (Tg) of all these mixes were determined by low-temperature DSC, which showed a lowering of Tg with a single peak. Rheological evaluation revealed that the viscosity of the binder is sufficiently lowered with an increase in flow behaviour on addition of 20% (w/w) plasticizer. The addition of 20% DEGDN has the maximum effect on the lowering of the viscosity of PGN. Quantum chemically derived molecular electrostatic potential (MESP) shows the possible sites of interaction of plasticizers and binder with the estimated lowest Vmin values and their magnitudes provide an insight into their mutual interactions. The relative trend in interaction energies between plasticizer and binder, PGN, is well correlated with a corresponding trend in the ability of plasticizers towards reducing the viscosity of PGN. The information gathered in the present study would in general be valuable with respect to designing new plasticizers.

Studies on metal salts of 4-(2,4,6 - trinitroanilino) benzoic acid

Abstract Synthesis, characterization and thermal studies of copper and lead salts of 4-(2,4,6-trinitroanilino) benzoic acid have been carried out. Differential thermal analysis data show that Pb2+ and Cu2+ salts are stable up to 240 and 260°C respectively and then decompose exothermically. Impact sensitivity value (h50) is 77 cm for lead salt and 170 cm for copper salt. Both the salts are found friction insensitive upto 36 kg. The calorimetric values of lead and copper salts are 679 and 839 cal/g, respectively.

Studies on the utilization of stripping voltammetry technique in the detection of high-energy materials

Research and development activities are on in many laboratories to develop methods for detecting energetic materials at the trace level. Production or application of high-energy materials may also contaminate the natural environmental systems. Therefore, development of a simple, portable, and inexpensive device for determining explosives at the trace levels is highly desirable. In this study, a stripping voltammetry technique is used for their analytical determination. The study is conducted in an acetonitrile medium. Optimum conditions are obtained in stripping voltammetry for individual analytes. The stripping voltammetric method is compound-selective and can be used for determining a particular high-energy material in a mixture. In this paper, we report the development of an electro-analytical procedure for detecting conventional energetic materials such as Tetryl, TNT, PETN, RDX, and HMX, using the stripping voltammetric method.

Thermokinetic decomposition and sensitivity studies of 4,4ˊ-diamino-3,3ˊ-azoxy furazan (DAAF)-based melt cast explosive formulations

ABSTRACT 4,4ˊ-diamino-3,3ˊ-azoxy furazan (DAAF) is an insensitive high explosive. DAAF has safety characteristics (impact, friction) similar to triaminotrinitrobenzene and shock sensitivity similar to HMX. The present article describes the thermal analysis and sensitivity study of DAAF with RDX and 2,4,6-trinitrotoluene (TNT). DAAF has been evaluated as a possible replacement for RDX in TNT-based, aluminized as well as nonaluminized melt cast formulation. DAAF-based melt cast formulations were characterized for their sensitivity to mechanical stimuli, bomb calorimetric analysis, and thermal decomposition behavior. The thermal analysis reveals the compatibility of DAAF with benchmark explosives like RDX and TNT in explosive formulations. The composition DT (DAAF + TNT) and DTA (DAAF + TNT+ Al) is more friction and impact insensitive as compared to RT (RDX + TNT) and RTA (RDX + TNT+ Al) compositions. The bomb calorimetric values of DT composition as well as DTA composition are higher than RT and RTA compositions. The result shows that DAAF can be effectively used as a RDX replacement in melt cast explosive formulations. DT-based aluminized composition showed more thermal stability than RT- and RTA-based control compositions, which clearly revealed the usefulness of DAAF for enhanced blast effect.

Correction: Understanding the reactivity of bis(propargyl) aromatic esters towards GAP: a theoretical exploration

Correction for ‘Understanding the reactivity of bis(propargyl) aromatic esters towards GAP: a theoretical exploration’ by Sanjeevani H. Sonawane et al., New J. Chem., 2017, DOI: 10.1039/c7nj01172e.