A 2-FLUID MODEL IN HYDRODYNAMICS OF DILUT E-SOLUTIONS OF FLEXIBLE-CHAIN POLYMERS

A two-fluid model in which a macromolecule is represented by a closed volume of a solution of monomer units, within which the monomer units are constrained by an external field which tends to establish a given distribution of local monomer unit density. The variation of local den sity is described by the equations for hydrodynamics of fluid mixtures exposed to an external field. The model is significantly simplified w hen the concentration of monomer units inside the coil is assumed to b e extremely low. Plots of diffusion coefficient and intrinsic viscosit y versus hydrodynamic interaction parameter are used to compare the ne w model with the models reported previously. A two-fluid model is sign ificantly simpler than the well-known ''pearl necklace'' model and, in contrast to a largely similar porous rigid sphere model, takes into a ccount the variation of local density caused by the flow, although it underestimates the effects due to hydrodynamic interactions. Ways to i mprove the model are discussed.