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A number of nanocomposites have been synthesized biomimetically by embedding various transition metal salts in polyvinyl alcohol (PVA) as the preorganised matrix. The metal salts were reduced to metallic form using aqueous sodium borohydride solution. In the present paper, very comprehensive studies on thermal decomposition behavior of these composites have been carried out using thermogravimetric and differential scanning calorimetric studies. The transition metal salts/ metals based composites exhibit increased thermal stability as indicated by shift in the decomposition temperature of pure PVA. The DSC data show increase in glass transition temperature of all composites, except the one containing iron, in comparison with neat PVA.The improvement in the thermal stability is explained in terms of decrease in the segmental mobility of polymer chains due to entrapment of metal salt / metal forming a complex with the hydroxyl group of the polymer chains and thus decreasing heat transfer process for decomposition of polymer composites.

A number of fuel blends based on 3‐carene, norbornadiene, furfuryl alcohol, ethylidene norbornene, and kerosene in different weight proportions have been developed as rocket fuels which exhibit synergistic hypergolic ignition with red fuming nitric acid (RFNA) as oxidizer with low ignition delays (IDs<40 ms). The optimum compositions of fuel blends were determined by measuring ID values of different blends at optimum O/F ratios. Eight selected fuel blends and one neat fuel (ethylidene norbornene) were theoretically evaluated for their performance parameters using NASA‐CEC‐71 software with RFNA as oxidizer at different O/F ratios and at chamber pressure of Pc, 2451.66 and 4903.33 (or 5197.52) kPa, keeping the exit pressure constant at 98.07 kPa. For experimental validation of performance parameters, static firing trials of these fuel blends with RFNA were carried out using 735.5 N thruster at 2451.66 kPa chamber pressure using doublet or triplet impinging stream type of injector. The experimental C* values were compared with theoretically determined C* values to predict combustion efficiencies which were found to be more than 95% in all the cases.

Hypergolic fuel has unique importance in missiles and satellite launch vehicles. Hydrazine and its derivatives (Monomethyl hydrazine, MMH and Unsymmetrical Dimethyl Hydrazine, UDMH) are the continuous choices of fuel in bipropellant though it is carcinogenic and toxic. Development of new, green and costeffective fuel blends based on trust-worthy, ionic liquid and biofuel in different volume proportion have been reported. The blends exhibit reasonably good stability (chemical and thermal), low viscosity (h < 15 mPa·s), high density (1 > 1 g/cm 3 ), low ignition delay and high performance in comparison with UDMH -a proven liquid fuel presently being used as promising fuels for liquid rocket application. The reported blends appear to be a technologically promising, eco-friendly and affordable fuel blend to replace currently used liquid toxic fuels.Hypergolicity is a desirable property of liquid bipropellant for rocket application. It is the self-igniting tendency of fuel when it comes in contact with a liquid oxidizer. It is measured in terms of ignition dealy (ID), which is a time, lapsed between a physical contact of fuel and oxidizer, and the appearance of the flame. A shorter ID is very desirable for the safe and reliable functioning of the liquid rocket engine. The ID less than 50 ms is the acceptable limit for liquid bipropellant engines. [1] It depends on some physical parameters like mixing, mixing rate, droplet size and the diffusion rate of fuel and oxidizer. [2,3] The ID also depends upon the chemical reactivity of fuel and oxidizer, the chamber pressure, the oxidizer and fuel weight ratio, etc. In this context, the pre-ignition reaction plays a very important role. If the amount of heat generated during pre-ignition reaction is sufficient to take the fuel to its ignition temperature, then only ignition will take place. If the pre-ignition reaction fails to generate the required heat, then ignition may not take place, and only vigorous chemical reactions may be exhibited. If the system is hypergolic in nature, it does not require an external ignition source, and thus, the system becomes more reliable, and offers the start-restart capability to the engine. [2,4] Therefore, a hypergolic fuel presents unique importance of liquid fuel in bipropellant.