CONCENTRATION DEPENDENCY OF SEDIMENTATION CONSTANT

Recently we have calculated the Huggins constant in terms of the characteristic relaxation spectrum. Here we apply the same method to the coefficient ke, which is defined by s/s0=1-k 2c⋯ , where s is the sedimentation constant at the polymer weight concentration c, and so is that at infinite solution. It is found that k4, is related to the expansion coefficient a, (determined by viscosity measurements) and to the molecular weight of the polymer in the following manner: k4= C0M1/2(α η-αη-1), where C0 is a constant dependent on the unperturbed dimensions of the polymer coil. This equation is compared with recent experiments by Nagasawa and by Cowie and good agreement is obtained. Thus, plots of k4 against M1/2 (αη-αη-1) give excellent linearity.