Diaminofurazan (DAF): Thermolysis and evaluation as ballistic modifier in double base propellant.
ABSTRACT Diaminofurazan (DAF) is used as a precursor in the synthesis of many high performance insensitive high explosives. This paper reports the thermal studies on DAF and its evaluation as a ballistic modifier in double base propellant formulations. Differential scanning calorimetry (DSC) and differential thermal analysis (DTA) revealed that DAF shows two-stage decomposition, whereas the kinetics of initial stage of thermal decomposition of DAF evaluated from TG data gave activation energy (E(a)) of 67 kJ mol(-1). The evolution of gases containing species such as CN, NH, OH and oxides of nitrogen during thermal decomposition of DAF was also revealed by hyphenated TG-FTIR data. Evaluation of DAF as a ballistic modifier in RDX incorporated double base propellant formulations indicated that it brings down the pressure index to 0.20 compared to 0.70 for a control composition in the pressure range 6.9-8.8 MPa when used in combination with basic lead salicylate (BLS). It was observed that DAF does not have adverse effect on vulnerability and chemical stability of the propellant formulation.
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ABSTRACT: 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.Journal of Hazardous Materials 05/2008; 161(2-3):589-607. · 3.93 Impact Factor
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ABSTRACT: We report the first experimental and theoretical study of gas phase excited electronic state decomposition of a furazan based, high nitrogen content energetic material, 3,3'-diamino-4,4'-azoxyfurazan (DAAF), and its model systems, diaminofurazan (DAF) and furazan (C2H2N2O). DAAF has received major attention as an insensitive high energy explosive; however, the mechanism and dynamics of the decomposition of this material are not clear yet. In order to understand the initial decomposition mechanism of DAAF and those of its model systems, nanosecond energy resolved and femtosecond time resolved spectroscopies and complete active space self-consistent field (CASSCF) calculations have been employed to investigate the excited electronic state decomposition of these materials. The NO molecule is observed as an initial decomposition product from DAAF and its model systems at three UV excitation wavelengths (226, 236, and 248 nm) with a pulse duration of 8 ns. Energies of the three excitation wavelengths coincide with the (0-0), (0-1), and (0-2) vibronic bands of the NO A 2Sigma+<--X 2Pi electronic transition, respectively. A unique excitation wavelength independent dissociation channel is observed for DAAF, which generates the NO product with a rotationally cold (20 K) and a vibrationally hot (1265 K) distribution. On the contrary, excitation wavelength dependent dissociation channels are observed for the model systems, which generate the NO product with both rotationally cold and hot distributions depending on the excitation wavelengths. Potential energy surface calculations at the CASSCF level of theory illustrates that two conical intersections between the excited and ground electronic states are involved in two different excitation wavelength dependent dissociation channels for the model systems. Femtosecond pump-probe experiments at 226 nm reveal that the NO molecule is still the main observed decomposition product from the materials of interest and that the formation dynamics of the NO product is faster than 180 fs. Two additional fragments are observed from furazan with mass of 40 amu (C2H2N) and 28 amu (CH2N) employing femtosecond laser ionization. This observation suggests a five-membered heterocyclic furazan ring opening mechanism with rupture of a CN and a NO bond, yielding NO as a major decomposition product. NH2 is not observed as a secondary decomposition product of DAAF and DAF.The Journal of Chemical Physics 02/2008; 128(3):034303. · 3.12 Impact Factor
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ABSTRACT: The analytical applications of the evolved gas analysis (EGA) performed by infrared spectroscopy, for the period extending from 2005 to 2009, are collected in this review. By this technique, the nature of volatile products released by a substance subjected to a controlled temperature program are on-line determined, with the possibility to prove a supposed reaction, either under isothermal or under heating conditions.Applied Spectroscopy Reviews 01/2010; 45(4):241-273. · 2.92 Impact Factor