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Studies on NTO-, FOX-7- and DNAN-based Melt Cast Formulations

Mishra V. S., Vadali S. R., Bhagat A. L., Garg R. K., Kugaonkar V. M., Raman S., Sinha R. K., Asthana S.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 2

403--417

EN

In the present paper, 2,4-dinitroanisole (DNAN) has been evaluated as a melt cast explosive in comparison to the widely used 2,4,6-trinitrotoluene (TNT). The detonation failure diameter of a bare DNAN charge is greater than 100 mm and about 44 mm with 1.5 mm steel confinement. Comparative studies of two sets of formulations were carried out. The first set comprised formulations containing 60% of NTO, FOX-7, HMX or RDX and 40% of DNAN or TNT. The second set comprised formulations containing 30% of NTO, FOX-7, TATB or RDX and 70% of DNAN or TNT. The studies were mainly concentrated on characterization of the formulations, which included determination of the sensitivity parameters and the velocity of detonation (VOD). The study confirmed that DNAN and DNAN-based formulations are relatively insensitive compared to TNT and the analogous TNT-based formulations respectively. The rate of the detonation reaction of DNAN is enhanced in the presence of the high energy ingredients RDX, HMX, FOX-7 and NTO to varying degrees. The VODs of the FOX-7/TNT and RDX/TNT formulations match closely with the proportions of FOX-7 and RDX under study. The VOD and shock sensitivity of the FOX-7/DNAN formulations decrease rapidly compared to the RDX/DNAN formulations, with increases in the proportion of FOX-7 or RDX. The combinations of NTO with TNT, and NTO with DNAN, are more shock insensitive than TNT or DNAN alone. NTO-based compositions are more insensitive than FOX-7-based compositions.

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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).

3

Experimental Studies on a High Energy Sheet Explosive Based on RDX and Bis(2,2-dinitropropyl) Formal/Acetal (BDNPF/A)

Jangid S. K., Singh M. K., Solanki V. J., Pandit G., Nath T., Sinha R. K.

Central European Journal of Energetic Materials

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2016

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Vol. 13, no. 3

557--566

EN

A plastic bonded explosive (PBX) in the form of a sheet explosive was formulated with 1,3,5-trinitro-1,3,5-triazinane (RDX) dispersed in a polymeric matrix of a thermoplastic linear polyurethane and a 50/50 wt.% eutectic mixture of energetic plasticizers, viz., bis(2,2-dinitropropyl)formal (BDNPF) and bis(2,2-dinitropropyl)acetal (BDNPA) was used to increase the performance of the sheet explosive in terms of its velocity of detonation (VOD). The sheet explosives were prepared by a rolling process. Natural rubber (ISNR-5) based sheet explosive was taken as the standard composition. The study showed that the BDNPF/A based sheet explosive has a velocity of detonation of 7850 m/s, which is about 900 m/s higher than the standard composition. Thermal analysis of the sheet explosive formulations was performed using differential scanning calorimetry (DSC).

4

Studies on Tungsten Based High Density Cast Polymer Bonded Explosive (PBX) Formulations

Vadhe P. P., Manickam S., Rahujade N., Kondra A., Prasad U., Sinha R. K.

Central European Journal of Energetic Materials

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2015

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Vol. 12, no. 3

497--506

EN

Aluminized melt-cast TNT and PBX (cast/pressed) based compositions have been widely studied and used in different warheads for various applications,such as air blast, underwater blast, thermobaric effects, etc. Tungsten (W) based cast PBX formulations are the least reported in the literature. We have partially replaced RDX or HMX in the control PBX formulation with 15 to 25% W powder and investigated the effect of this on the ease of processing, density, sensitivity, mechanical properties and explosive performance. The viscosity was improved from 9 to 3 kPoise, and the density by about 12 to 25% on the addition of W powder to the PBX formulations. The sensitivity to impact for the RDX/Wand HMX/W based PBX formulations was improved by 12 to 37%. The reinforcing effect of the W powder caused an increase in hardness (Shore A) by 16 to 45%. A decreasing trend in the velocity of detonation (VOD) was observed because of the replacement of the nitramine content (RDX/HMX) with W powder. The approximate detonation pressure of RDX/W/HTPB (65/20/15), roughly calculated by the Kamlet-Jacobs method, is better than the other tungsten based formulations investigated.

5

Broad angle and frequency tunable photonic crystal-polarization beam splitter based on negative refraction: Transition from right-handed to left-handed medium

Rajput M., Sinha R. K.

Optica Applicata

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2011

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Vol. 41, nr 1

29--40

EN

A new design of a broad angle photonic crystal polarization beam splitter (PhC-PBS) with frequency tunable index of refraction, i.e. varying from positive to negative, is presented. Designed PhC-PBS shows transition from right-handed medium (positive index medium) to left-handed medium (negative index medium) with change in normalized frequency from 0.437 to 0.516. The design description includes band structure calculations and equi-frequency contour (EFC) analysis, where direction of refraction is tuned by the frequency and thickness of a slab. The proposed PBS splits transverse electric (TE) polarization in negative direction and transverse magnetic (TM) polarization in positive direction for optical communication windows in the range of 1.31 žm and 1.55 žm. Finite difference time domain (FDTD) method is employed to evaluate left-handed, right-handed transmission and reflection characteristics. High transmission and extinction ratio at wide range of incident angles validate proposed design as an efficient and broad angle PBS based on tunable negative refraction. Demonstration of near- and far-field resonance patterns reveals that proposed structure has the high potential in the design and development of the multiple photonic device applications, i.e., highly directional optical antennas also.