Rheological Behaviour of HTPB-based Composite Propellant: Effect ofTemperature and Pot Life on Casting Rate

Abstract

To study the rheological properties and the flow behaviour of HTPB based composite propellant, a typical mix was carried out with 86 per cent solid loading and toluene diisocynate (TDI) as curator. Viscosity of the propellant slurry was measured at different shear rates over a range of temperature from 40 ºC to 60 ºC at various time intervals up to five hours from end of mix. The data are analysed using power law fluid equation to determine the viscosity index (K) and pseudoplasticity index (m). From these, optimum casting temperature and useful pot life was evaluated. Casting rates at different temperatures were determined by Haegen-Poisseuille equation modified for non-Newtonian fluid flow, using K and m.

Studies on the effect of plasticiser and addition of toluene diisocyanate at different temperatures in composite propellant formulations

“…Moreover, composite propellant mixtures are heterogeneous in nature and binders used in such systems are bi-functional and always cured with bi-functional curatives (TDI). Because of the chemical reaction between -OH and -NCO groups of HTPB and TDI, respectively, the nature of mixtures becomes non-Newtonian [17,18]. Thus, the viscosity of slurry/mixture increases on increasing time indicates time dependent mixture.…”

HTPB-Polyurethane: A Versatile Fuel Binder for Composite Solid Propellant

“…For nonNewtonial material, if the viscosity decreases with shear, the rate of decrease is the measure of pseudoplasticity of the material. The flow of highly loaded propellant slurry (86 % solid loading) can be more closely approximated by the Power Law fluid model (Mahanta et al, 2007). The pseudoplasticity index (PI) and viscosity index were calculated from the curve by fitting to a Power Law equation i.e.…”

“…The information of change on viscosity during the curing process is critical in modelling the PU flow behaviour. Though extensive works have been carried out on this topic in the last decade (Muthiah et al, 1992, Lakshmi & Athithan, 1999, Singh et al, 2002& Mahanta et al, 2007, it is still a fascinating research area at present. The thermal decomposition of HTPB has been studied exclusively in inert atmosphere (Panicker & Ninan, 1997).…”

Pseudoplasticity of Propellant Slurry with Varied Aluminium Content for Castability Development

“…According to Dombe et al (2008), slurry of composite propellants usually have n of 0,6 -1. [9], [3], [10] …”