Generalized correlations for molecular weight and concentration dependence of zero-shear viscosity of high polymer solutions

Data are presented to show that two correlations of viscosity–concentration data are useful representations for data over wide ranges of molecular weight and up to at least moderately high concentrations for both good and fair solvents. Low molecular weight polymer solutions (below the critical entanglement molecular weight M_c) generally have higher viscosities than predicted by the correlations. One correlation is η_sp/cη] versus k′η], where η_sp is specific viscosity, c is polymer concentration, η] is intrinsic viscosity, and k′ is the Huggins constant. A standard curve for good solvent systems has been defined up to k′η]c ≈? 3. It can also be used for fair solvents up to k′η]c ≈? 1.25· low estimates are obtained at higher values. A simpler and more useful correlation is η_R versus cη], where η_R is relative viscosity. Fair solvent viscosities can be predicted from the good solvent curve up to cη] ≈? 3, above which estimates are low. Poor solvent data can also be correlated as η_R versus cη] for molecular weights below 1 to 2 × 10⁵.