SEDIMENTATION EQUILIBRIUM OF POLYDISPERSE NONIDEAL SOLUTES: A COMPARISON OF THREE APPROXIMATIONS*

AUTOR(ES)
RESUMO

In the evaluation of sedimentation equilibrium data for polydisperse nonideal solutions, extrapolation procedures are required for the determination of the true solute weight-average molecular weight and of the light-scattering second virial coefficient. In an attempt to decide just which concentration-dependent parameter should be used in making these extrapolations, Van Holde and Williams, J. Polym. Sci., 11, 243 (1953), and Fujita, J. Phys. Chem., 63, 1326 (1959), and ibid., 73, 1759(1969), have derived relations between apparent and true weight-average molecular weights which, starting from approximate forms of the same differential equations, appear to give different working expressions. The present analysis of these results will demonstrate new and perhaps unexpected relations between them.

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