A study of the effect of temperature on a mixture of polymer and curative in the processing of rocket propellants is reported. Experimental viscosity of a hydroxyl-terminated polybutadiene-toluene diisocyanate (HTPB-TDI) system was measured using a Brookfield viscometer model DV III. Viscosity showed dependence on temperature as well as time. The viscosity data of the HTPB-TDI system showed a linear relationship with temperature, with a change in slope at 45degreesC. The time dependence model showed a fourth-order curve fit, which gave better results over the exponential model fit. The activation energy required for flow of the HTPB-TDI system was found to be 15.5 kJ/mol. Experimental viscosity measurements at various temperatures was also carried out on a hydroxyl-terminated polybutadiene-dioctyl adipate -toluene diisocyanate (HTPB-DOA-TDI) system. The temperature dependence showed a decrease in viscosity with an increase in temperature up to 60 min, beyond which the viscosity increased. Viscosity showed a linear relation with temperature, with a change in the slope at 50degreesC instead of at 45degreesC for HTPB-TDI system. Beyond 50degreesC the data followed a polynomial model similar to that of the HTPB-TDI system, and the results matched well with the experimental data. The activation energy of the HTPB-DOA-TDI system increased with an increase in the binder weight ratio. (C) 2003 Wiley Periodicals, Inc.