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Telechilic polybutadiene solid propellant binders based on click chemistry approach

Reshmi, S and Arunan, E and Nair, CPR (2017) Telechilic polybutadiene solid propellant binders based on click chemistry approach. [Book Chapter]

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Official URL: https://www.researchgate.net/publication/321668779...


Solid propellants are widely used for launch vehicle and missile applications. The polymeric fuel binder is a critical ingredient of a composite solid propellant. It acts as the matrix for holding together the oxidiser, metallic fuel and other additives and also imparts structural integrity, mechanical properties to the propellant and contribute to the combustion phenomena. In recent years, the impetus has been to improve the energetics by the use of binders with energetic functional groups. The introduction of ‘triazole’ groups in the polymer network via ‘Click chemistry’ is one such approach. This imparts superior processability, mechanical properties and ballistics to the propellant. Amongst the different types of polymeric binders used in composite solid propellants, hydroxyl terminated polybutadiene (HTPB) is considered as the most versatile. In the present approach, hydroxyl terminated polybutadiene (HTPB) was chemically modified to derive propargyl end capped polymers. The polymers were then cured by ‘Click Chemistry’ approach to form triazole network using an azide bearing polymer viz. Glycidylazide polymer (GAP) referred to as PTPB triazole. The curing parameters were studied using Differential Scanning Calorimetry (DSC). Curing occurs only for an alkyne:azide molar equivalence of 1:0.1 and beyond this stoichiometry, phase separation occurs. Rheological studies of PTPB triazole was carried out and the properties were compared with HTPB-tolylenediisocyanate (TDI) based urethane system (based on hydroxyl: isocyanate). The studies revealed that the gel time for curing through the 1, 3 dipolar addition is higher for triazole curing route than urethanes based systems indicating a higher ‘pot life’. The mechanical properties of the triazole mediated networks were evaluated and compared to those of HTPB-urethanes. Thermo gravimetric analysis (TG) of the triazoles derived from the polymers were investigated and the mechanism of decomposition of PTPB triazole with AP as oxidiser was elucidated by pyrolysis GC-MS.The propellant level properties of PTPB triazolewere evaluated and compared with propellants based on HTPBurethane system. The studies reveal that propellant based on PTPB triazolehavesuperior processabilitywith acceptable mechanical properties, than HTPB-urethanes It also provide improved ballistic properties in terms of higher gas generation during combustion.

Item Type: Book Chapter
Publication: Click Chemistry: Approaches, Applications and Challenges
Publisher: Nova Science Publishers, Inc.
Additional Information: The copyright for this article belongs to Nova Science Publishers, Inc.
Keywords: Ballistics; Binders; Combustion; Composite propellants; Curing; Differential scanning calorimetry; Esters; Explosives; Fuel additives; Functional groups; Gravimetric analysis; Mechanical properties; Phase separation; Polybutadienes; Polyols; Synthesis (chemical); Thermogravimetric analysis, Ballistic properties; Chemically modified; Combustion phenomena; Composite solid propellant; Hydroxyl terminated polybutadienes; Mechanism of decomposition; Missile applications; Rheological studies, HTPB propellants
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 14 Aug 2022 04:59
Last Modified: 14 Aug 2022 04:59
URI: https://eprints.iisc.ac.in/id/eprint/74726

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