Pot life extension of hydroxyl terminated polybutadiene based solid propellant binder system by tailoring the binder polymer microstructure

ABSTRACT

A possibility of extending the pot life of the HTPB-TDI based propellant binder system without adverse modification of mechanical properties is explored in the present study. It is proposed that by tailoring functionality distribution of the base HTPB polymer and changing the binder composition concurrently, the pot life of the binder system can be extended while the mechanical characteristics are kept within the acceptability window. Using an existing empirical relationship between fraction of high molecular weight (Fh) in HTPB and r-value corresponding to a more optimized set of mechanical properties, the r-values were calculated for different HTPB resins. HTPB resins with widely varying fractions of high molecular weight (Fh) were chosen and binder networks were prepared at different r values. Viscosity build up and chemical kinetics were studied for different formulations. From the studies, it is shown that the extension of pot-life is achievable by about 150 minutes without sacrificing the mechanical characteristics.

KEYWORDS:

• High molecular weight fraction
• HTPB
• pot life
• propellant
• TDI
• viscosity

Acknowledgments

The authors wish to express their thanks to Smt. Chandrakumari Amma for helping to evaluate the viscosity build up profile.