Modified bead-spring theory of dilute polymer solutions. II. Effects of polydispersity and comparison with experiment



A constitutive equation, previously derived for dilute, monodisperse solutions of linear macromolecules, is extended to include polydisperse solutions. This result, which represents a coupling of continuum and molecular theory, realistically portrays the effects of molecular weight and molecular weight distribution on mechanical behavior. Intrinsic viscosity–shear rate data are well described, and with certain semiempirical modifications the equation also fits normal stress and dynamic viscosity data for slightly more concentrated solutions. Some unusual effects associated with the characterization of macromolecular degradation, in studies of turbulent drag reduction, are also explained.