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Viscoelastic properties of hydroxyl-terminated poly(butadiene) based composite rocket propellants
In the present study, the viscoelastic response of three composite solid
propellants based on hydroxyl-terminated poly(butadiene), ammonium
perchlorate and aluminum has been investigated. The investigation was
surveyed by dynamic mechanical analysis over a wide range of temperatures
and frequencies. The mechanical properties of these materials are related to
the macromolecular structure of the binder as well as to the content and
nature of solid fillers. The storage modulus, loss modulus, loss factor and
glass transition temperature for each propellant sample have been evaluated.
The master curves of storage (log G' vs log ω) and loss modulus (log G'' vs
log ω) were generated for each propellant. A comparison of logaT vs
temperature curves for all propellants indicate conformance to
Williams-Landel-Ferry equation. Choosing the glass transition as the
reference temperature, WLF equation constants are determined. Fractional
free volume at the glass transition temperature and thermal coefficient of
free volume expansion values are in accordance with the consideration that
Al is reinforcing filler