Modification of Stokes-Einstein Equation for Diffusivities in Dilute Polymer Solutions

An improved correlation is presented for the estimation of binary diffusion coefficients in various dilute polymer solutions. The correlation is based on the Stokes-Einstein equation with empirical corrections for the nonroundness and the size ratio of polymer and solvent molecules. These corrections are computed from the UNIQUAC or UNIFAC group contribution R and Q parameters. The method works well for various polymer systems. The proposed correlation reduced the average error from 133% to 33%.