REPUBLIC OF SERBIA

MINISTRY OF DEFENCE

www.mod.gov.rs

MINISTRY OF DEFENCE

Material Resources Sector

Defensive Technologies Department

Military Technical Institute

www.vti.mod.gov.rs

VISCOELASTIC PROPERTIES OF COMPOSITE ROCKET PROPELLANTS BASED ON HYDROXYL-TERMINATED POLY(BUTADIENE) AND ISOPHORONE DIISOCYANATE POLYURETHANE

saša brzić

BRANKA POPOVIĆ

Military Technical Institute, Belgrade, odsekbaric@gmail.com,

MILOŠ TOMIĆ

Faculty of Technology and Metallurgy, University of Belgrade, milost86@yahoo.com

Abstract: The aim of this work was to evaluate viscoelastic behaviour of composite rocket propellant (CRP) based on polyurethane. Polymer matrix is consisted of hydroxyl-terminated poly(butadiene)-HTPB and isophorone diisocyanate-IPDI as a curing agent. Propellant selected for this study contained 85% solids loading. Also, temperature and frequency dependence of dynamic mechanical properties – storage modulus, (G´), loss modulus, (G'') and loss tangent, (tanδ  =  G˝/G´) are presented. Shift factors, a_T, and coefficients, C₁ and C₂ in WLF equation are determined. A good agreement were observed between the experimental and calculated values of the shift factors, a_T, so one can conclude that, for tested CRP sample, WLF equation with calculated values of constants C₁ and C₂ is valid in whole temperature range of test.

Key words: dynamic mechanical analysis, composite rocket propellants, master curve, WLF equation.