FLOW-DEPENDENT REJECTION OF POLYSTYRENE FROM MICROPOROUS MEMBRANES

Dilute solutions of polystyrene (molecular weight 1 multiplied by 10**5-2 multiplied by 10**7) in a mixed solvent of 90% carbon tetrachloride-10% methanol were filtered through track-etched porous mica membranes. The reflection coefficient sigma , defined as the fraction of polymer held back by the membrane, was measured as a function of polymer size r, pore radius r//0, and solvent flow rate q through each pore. Polymer size was characterized by the Stokes-Einstein radius, as determined from diffusion coefficients measured by quasielastic light scattering, and chain relaxation times tau were estimated from measured intrinsic viscosities.