Diffusion in elastic fluids

Abstract

Diffusion coefficients for KCl have been determined by the capillary method of Anderson and Saddington [J. Chem. Soc. S381, 381-386 (1949)], using 36Cl- tracer in corn syrup solutions of two different viscosities. Values of the diffusion coefficient were obtained both for the original corn syrup solutions and for the same solution after addition of small amounts of polyacrylamide to introduce elasticity ("Boger fluids"). The results indicated that the diffusivities for the latter were increased by 55% and 18% respectively, as compared with the unmodified fluids. A qualitative explanation of this effect is proposed in terms of changes to the drag exerted on the molecule as a result of increas..