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Influence of Guanylurea Dinitramide (GUDN) on the Thermal Behaviour, Sensitivity and Ballistic Properties of the B-KNO3-PEC Ignition System

Badgujar D. M., Phatak S., Wagh R. M., Bhingarakar V., Talawar M. B., Kakade S. D.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 2

315--326

EN

Boron and potassium nitrate are the key components for the ignition system of the igniter composition for rocket propellants. Boron-potassium nitrate-ethyl cellulose (B:KNO3:PEC) in proportions of 30:70:10 is a well established igniter composition. The composition delivers a maximum pressure in the range 4.0-4.6 MPa in closed vessel firing at a loading density of 0.01 g/cm3. For the effective ignition of a large booster stage propellant (length more than 4 m), an enhancement in the maximum pressure, without affecting safety, is a prime requirement. The use of guanylurea dinitramide (GUDN) in an igniter composition has not been reported in the literature. Hence, the present study on the effect of GUDN on the combustion behaviour and sensitivity of the B/KNO3 composition (30/70) has been carried out. Several compositions containing different weight percents of GUDN were prepared. Their thermal behaviour was determined by thermal analysis DSC-TGA. Their sensitivities to external stimuli such as impact, friction and spark were evaluated. The results of closed vessel firings indicated that GUDN-based igniter compositions produced higher peak pressures (up to 4.5 MPa to 5.8 MPa), with invariably lower burning times, compared to the control composition. The REAL computer programme indicated an increase in the flame temperature of the composition from 2238 K to 2425 K on addition of GUDN. All of the compositions were insensitive towards friction up to 36 kg, and towards spark up to 5 J energy.

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Review of Promising Insensitive Energetic Materials

Badgujar D. M., Talawar M. B., Mahulikar P. P.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 4

821--843

EN

During the last twenty years military explosives, and energetic materials in general, have changed significantly. Worldwide, research and development programs are active in developing promising insensitive HEMs with higher performance. This has been due to several factors, which include new operational requirements such as Insensitive Munitions (IM), but it is also due to the availability of new materials and to new assessment and modelling techniques. The present review focuses on the basic idea and necessity for IM, and the conditions, technical requirements and tests for IM. The review also explains the various promising insensitive high explosives, their synthesis and formulation used in different propellants.

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An Improved Safe Method for the Synthesis of Ammonium 5-Nitrotetrazolate (ANT), a Key Intermediate for the Synthesis of Green Energetic Materials (GEMs)

Marimuthu A., Talawar M. B.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 4

861--875

EN

Ammonium 5-nitrotetrazolate (ANT) is an important precursor for the synthesis of green energetic materials (GEMs), including lead/mercury-free environmentally benign primary explosives. The currently employed methods for the synthesis of ANT are hazardous, use an excess of organic solvents/reagents and thus generate effluent. Furthermore, these methods offer low yields of ANT as they involve multistep processes. We describe herein an improved, safe and convenient method for the synthesis of ANT, which greatly improves the process safety and product yield. The advantage of this method is that it avoids hazardous operations, such as the isolation and handling of acidic copper(II) nitrotetrazolate, an extremely sensitive explosive intermediate during the preparation of ANT. In our procedure, 5-aminotetrazole (5-AT) is diazotized with sodium nitrite and nitric acid in the presence of a copper salt. The sensitive copper acid salt thus formed from the reaction mixture is treated in situ with aqueous barium hydroxide to convert it to barium 5-nitrotetrazolate and insoluble copper oxide. Finally, the aqueous barium 5-nitro-1H-tetrazolate (BaNT) is treated with ammonium sulfate to yield ammonium 5-nitrotetrazolate (ANT) in good yield. The synthesized ANT was characterized by its physicochemical properties using spectral and thermal techniques. The purity of the ANT was measured by HPLC and ion chromatography (IC). Furthermore, the structure of ANT was confirmed by single crystal X-ray analysis.

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Experimental Studies on Advanced Sheet Explosive Formulations Based on 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and Hydroxyl Terminated Polybutadiene (HTPB), and Comparison with a RDX-based System

Jangid S. K., Talawar M. B., Singh M. K., Nath T., Sinha R. K.

Central European Journal of Energetic Materials

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2016

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Vol. 13, no. 1

135--147

EN

The present investigation reports the use of 2,4,6,8,10,12-hexanitro2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) in sheet explosive formulations. In this study, hydroxyl terminated polybutadiene (HTPB) based sheet explosives were prepared incorporating the powerful explosive CL-20 as a partial replacement for hexahydro-1,3,5-trinitro-1,3,5-triazine(RDX). The effects of incorporating CL-20 on the performance, sensitivity, thermal and mechanical properties of the sheet explosive compositions are reported. Sheet explosive formulation containing 80% of RDX and 20% of HTPB-binder was studied as control sample. HTPBbinder consisted of 12% HTPB, 2.9% dioctyl adipate (DOA) and 5.1% dioctyl phthalate (DOP). HTPB was cured with 4,4’-methylene diphenyl di-isocyanate (MDI) to form urethane linkages. The incorporation of 20% of CL-20 in place of RDX led to a remarkable increase in the velocity of detonation (VOD), of the order of 7680 m/s, and to better mechanical properties in terms of tensile strength (1.14 MPa) compared to the control formulation [RDX /HTPB-binder (80/20)]. The 20% CL-20 incorporated sheet explosive formulation also showed remarkable increases in impact and shock sensitivity. Thermal analysis of the sheet explosive compositions has also been carried out using differential scanning calorimetry (DSC).

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Towards New Directions in Oxidizers/Energetic Fillers for Composite Propellants: an Overview

Dey A., Sikder A. K., Talawar M. B., Chottopadhyay S.

Central European Journal of Energetic Materials

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2015

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Vol. 12, no. 2

377--399

EN

There is continued interest in the development of safe and reliable composite propellant formulations using modern energetic ingredients such as energetic oxidizers/energetic ingredients, energetic binders, and energetic ballistic modifiers. There are continued efforts by energetic materials researchers, scientists, technologists and engineers to design composite propellant formulations with better ballistic properties than conventional formulations. The efforts in many research and development (R & D) laboratories all over the world are aimed at utilizing modern oxidizers/ energetic fillers for the development of composite propellant formulations for both space and defence applications. Composite propellants are considered to be the major source of chemical energy for rockets and missiles. Energetic oxidizers/fillers play vital roles in the preparation or manufacture of composite propellant formulations. Various energetic oxidizers/fillers have been developed during the last five decades to address environmental safety, high energy and processing conditions. In this article, the authors have reviewed the characteristic properties of the energetic oxidizers/fillers used in the preparation of composite propellants. The characteristic properties of the energetic ingredients play an important role in the preparation of composite propellant formulations with the desired mechanical properties. The advantages and disadvantages of various energetic oxidizers/ingredients for specific and potential propellant applications are also highlighted throughout the course of this review article. The future direction in composite propellant formulations calls for the development of green propellant formulations. Efforts will continue to seek alternative and more energetic oxidizers/fillers in comparison to conventional oxidizers. There is an urgent need to replace conventional oxidizers such as ammonium perchlorate with eco-friendly ingredients.