Assessment of applicability of carreau, ellis, and cross models to the viscosity data of resin solutions

In this study, three popular rheological models, which fit adequately well to viscosity data of polymeric materials, are chosen for making a comparative assessment of their applicability to practical data. The resulting nonlinear equations of the three models are solved by using Levenberg Marquardt's algorithm. The assessment of their applicability to practical viscosity data of 66 solutions of two resins in 11 solvent systems and reported data of other polymers has been analyzed. The Carreau and Ellis models have yielded unique global estimates for various rheological parameters, whereas the Cross model yielded local solutions. However, both Carreau and Cross models yielded parameter estimates with low overall residual error. The three models are found to have good applicability to viscosity data of resin solutions in good and moderate solvents; however, some deviation is observed when they are tested for solvents in which the resin has poor solubility.