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4 Central European Journal of Energetic Materials

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Composite Propellant Formulation of Poly (16-, 32- and 64-) Azido Dendritic Esters as Energetic Plasticizer and Evaluation of Properties

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Yamajala K. D. B. , Singh H. , Kurva R. , Maurya M. , Banerjee S.

Central European Journal of Energetic Materials

2020

tom Vol. 17, no. 4

506--522

16-, 32- and 64-Polyazido hyperbranched dendrimers were synthesized from hydroxy terminated dendritic ester by following two steps namely, tosylation and azidation. The poly azido dendrimers were incorporated in composite propellant formulations as an energetic plasticizer. The physical, thermal sensitivity and ballistic properties of these composite propellants such as burning rate, Cal-val, density, ignition/decomposition temperature (AET), DSC-TGA, mechanical properties, impact and friction sensitivity were evaluated experimentally while the specific impulse (Isp) and characteristic velocity (C*) were obtained theoretically. A significant enhancement in heat release was noted in the propellant formulation having 16-azido dendritic ester as an energetic plasticizer compared to 32- and 64-azido dendritic esters and a reference composition.

Thermal Hazards Studies for the Azidation Process in the Preparation of Tetra Functional Glycidylazide Polymer (t-GAP) Using a Thermal Screening Unit (TSU)

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Adak P. K. , Ghosh M. , Meena A. K. , Jain M. , Banerjee S.

Central European Journal of Energetic Materials

2024

tom Vol. 21, no. 3

282--297

Glycidylazide polymer (GAP) tetraol or tetra functional GAP (t-GAP) is a potential energetic binder, capable of exhibiting superior mechanical properties and better curing behaviour for application in high energy propellants. t-GAP is conventionally prepared through azidation of tetra functional poly-epichlorohydrin (t-PECH). Azidation reactions using a metal azide are known to be sensitive to temperature. The present study was aimed at a systematic evaluation of the safe temperature limit for the preparation of t-GAP and to derive optimized reaction conditions using a thermal screening unit (TSU), through both dynamic and isothermal heating experiments. The thermal hazard studies suggested that the azidation reaction is fairly stable at temperatures above 100 °C as it did not exhibit any abrupt rise in reaction temperature or pressure. The process was validated using laboratory scale batches and completion of the reaction was verified using FTIR spectroscopy.

Influence of Dispersion Methods on the Mechanical, Thermal and Rheological Properties of HTPB-based Nanocomposites: Possible Binders for Composite Propellants

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Ghosh K. , Kumar A. , Banerjee S. , Patro U. S. , Gupta M.

Central European Journal of Energetic Materials

2019

tom Vol. 16, no. 2

281--298

The present study reports on the methods of preparation for HTPB-clay nanocomposites and their mechanical, thermal and rheological properties for their functional utility as an improved binder system for composite propellants. HTPB-clay nanocomposites were prepared by dispersing organoclay Cloisite 30B (1-3 wt.%) in the polymer matrix by magnetic stirring and high shear mixing. Critical parameters like time, temperature and RPM were optimized. These nanocomposites were cured with toluene diisocyanate in the presence of the cure catalyst DBTDL. The dispersion of the nanoclay was evaluated by using small angle X-ray scattering (SAXS) and energy dispersive X-ray (EDX) spectroscopy. EDX suggested homogeneous distribution while SAXS revealed partial exfoliation of the clay particles in the polymer matrix. Superior dispersion of the nanoclay was obtained by high shear mixing. The tensile properties of the nanocomposites prepared by high shear mixing showed 10-20% more strength and elastic modulus. The nanocomposites showed thermal stability higher than the pristine HTPB. Swelling behavior revealed increased cross linking, and the rheological behavior exhibited higher viscosity of the nanocomposites. In addition, the clay amount was increased up to 10 wt.% and its effect on the mechanical, thermal and swelling behavior was observed. Theoretical performance predictions of composite propellants with nanocomposites revealed their possible functional utility.

Study of the Progress of Reaction in the Preparation of tetra-Functional GAP using FTIR Spectroscopy

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Adak P. K. , Meena A. K. , Ghosh M. , Sutar V. , Jain M. , Banerjee S.

Central European Journal of Energetic Materials

2024

tom Vol. 21, no. 2

138--152

Glycidyl azide polymer (GAP) with tetra hydroxyl functional groups or t-GAP is a potential energetic polymeric binder for application in both high energy propellants and high explosives. t-GAP is synthesized via azidation of the precursor tetrafunctional poly-epichlorohydrine (t-PECH) with sodium azide in DMSO solvent medium. In this article, process optimization and progress of chemical reaction for preparation of t-GAP is studied using FTIR spectroscopy and an attempt is made to predict the reaction kinetics with concentration profiling. The characteristic vibrational features corresponding to C‒N3 of t-GAP and C‒Cl of t-PECH have been used to monitor the progress of reaction.