TEMPERATURE-DEPENDENCE OF VISCOSITY OF POLYURETHANE POLYOL SOLUTIONS - APPLICATION OF RHEOLOGICAL MODELS

Polyurethane polyols were synthesized by reacting the diols with polyi socyanates. Viscosity of their 50% (w/w) solutions in various solvents has been determined at different temperatures by using Haake Roto Vis co RV12 Rotational Viscometer. The temperature dependence of viscosity data was solved by Levenberg Marquardt's algorithm by using nonlinear regression models based on WLF, Vogel, and Arrhenius equations. The T -g values obtained from WLF and Vogel equation are comparable to each other and these equations can be satisfactorily used for the analysis of temperature dependence of viscosity data of oligomer solutions. The residuals are random and the absolute average percentage error in ana lyzing the viscosity data by these equations is minimum. The values of constants in WLF equation are found to be system dependent and adjust able parameters. The predicted In eta values obtained from WLF and Vog el equations fit well with the plots of experimental In eta values as a function of temperature. (C) 1996 John Wiley & Sons, Inc.