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Studies on Curing of an Aluminized Ammonium Perchlorate Composite Propellant Based on Nitrile Butadiene Rubber Using a Quinol Ether of 1,4-Benzoquinone Dioxime

Singh Sudhir, Raveendran Sidharth, Kshirsagar Dhirendra R., Gupta Manoj, Bhongale Chetan J.

Central European Journal of Energetic Materials

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2022

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Vol. 19, no. 1

18--38

EN

The isocyanate-based curing agents used for polyurethane are toxic and hygroscopic in nature. In the present work, an alternate approach was adopted, a reaction between the unsaturated rubber having an α-methylene hydrogen atom and a dinitrosobenzene (DNB) - generating system (quinol ether of 1,4-benzoquinone dioxime, QE) without a catalyst, thus generating a cured system. QE is a novel curing agent for propellant applications which imparts the necessary curing. The curing reaction between nitrile butatadiene rubber (NBR) and quinol ether (QE) was studied by FTIR and the results revealed the formation of anil groups (Ar–C=N). The anil group results from the reaction between NBR and DNB, generated on decomposition of QE. Propellant formulations were prepared with variation of the curing agent from 0.2 to 0.5%. The composition and rheological, mechanical, ballistic and thermal properties of the resulting cured systems were investigated. The viscosity and spreadability were suitable for casting. The tensile strength, modulus, and hardness show an increasing trend and the elongation decreases on varying QE from 0.2 to 0.5% in the propellant. However, all of the compositions showed nearly the same burning rate and pressure exponent. The QE based curing system is non-hygroscopic and has extremely low toxicity. The experimental results revealed that the proposed curing agent may find application in explosives and propellants.

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Studies on the High Performance Characteristics of an Aluminized Ammonium Perchlorate Composite Solid Propellant Based on Nitrile Butadiene Rubber

Sudhir Singh, Sidharth Raveendran, Dhirendra Kshirsagar R., Gupta Manoj, Chetan Bhongale

Central European Journal of Energetic Materials

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2021

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Vol. 18, no. 4

492--511

EN

n the present study, a high performance composite solid propellant formulation was prepared based on nitrile butadiene rubber (NBR) and dibutyl phthalate (DBP) plasticizer, which has a longer pot life and high density specific impulse. The developed cost effective novel binder system was prepared with readily available raw materials (NBR and DBP). The formulation of the composition was performed by varying the content of the NBR/DBP binder in the range of 14-20%. The rocket performance characteristics were determined theoretically using PROPEP and compared with those of an HTPB based propellant. The rheological, mechanical, physical, ballistic and thermal properties of the NBR/DBP propellant were studied and compared with literature data for similar compositions based on an HTPB/dioctyl adipate (DOA) binder. The yield stress was determined by spreadibilty measurements, and indicated the superiority of this binder based propellant over existing composite propellants. It was concluded that following decreasing the content of the NBR/DBP binder in the propellant from 20 to 14%: in the range 58.83-78.45 bar (5.883-7.845 MPa), the pressure index increased from 0.159 to 0.371, – at 68.64 bar (6.864 MPa), the burning rate increased from 4.10 to 6.54 mm/s, but the theoretical specific impulse value did not change significantly (258.0259.8 s), – the tensile strength and E-modulus increased from 6.03 to 9.88 (0.591-0.969) to and from 18.00 to 75.00 kgf/cm2 (1.765 to 7.355 MPa), respectively. Moreover, a DSC and TGA study indicated a lower decomposition temperature for the NBR/DBP propellant compared to the HTPB propellant. The NBR/DBP propellant exhibited a pot life more than double that of a conventional HTPB/ DOA based propellant.

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

Ghosh Kavita, Kumar Arvind, Banerjee Shaibal, Patro Uma Sankar, Gupta Manoj

Central European Journal of Energetic Materials

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2019

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Vol. 16, no. 2

281--298

EN

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.

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Using Anthropogenic Waste (Steel Slag) to Enhance Mechanical and Wear Properties of a Commercial Aluminium Alloy A356

Sridhar Raja K. S., Bupesh Raja V. K., Gupta Manoj

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 1

279--284

EN

The present study addresses the utilization of induction furnace steel slag which is an anthropogenic waste, for enhancing the mechanical properties of a commercial aluminium alloy A356. Different weight percentage (3wt%, 6wt%, 9wt%, and 12wt%) of steel slag particles in 1 to 10 μm size range were used as reinforcing particles in aluminium alloy A356 matrix. The composites were prepared through stir casting technique. The results revealed an improvement in mechanical properties (i.e. microhardness and tensile strength) and wear resistance with an increase in weight percentage of the steel slag particles. This research work shows promising results for the utilization of the steel slag for enhancing the properties of aluminium alloy A356 at no additional cost while assisting at same time in alleviating land pollution.