Abstract
Current theories for the interpretation of sedimentation and viscosity data are discussed, with particular reference to those substances where experimental uncertainties preclude the application of the Scheraga-Mandelkern β function. Attention is directed to the ratio of Ks (the coefficient of concentration-dependence of the reciprocal sedimentation coefficient) to [η], the intrinsic viscosity. This ratio was reported by Wales and Van Holde to be a constant equal to about 1.6 for all random-coil polymers, and a theoretical basis for this constancy was derived; the ratio is also of fundamental importance in the “porous-plug” theory of Ogston and the polymer theory of Yamakawa. From a survey of existing data, it is shown here that compact spherical macromolecules also give Ks/[η] values of about 1.6, whereas those macromolecules known to be asymmetric give lower values. These observations form the basis of a method for distinguishing between the separate contributions of asymmetry and expansion of form to the intrinsic viscosity.
Published Version
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