ABSTRACT
In the limit of infinite dilution. polymer solution viscosity is linearly dependent on polymer concentration. This happens because the polymer molecules are so far apart that one molecule does not feel the presence of the other molecules. As a consequence. the solution viscosity is the product of the number of polymer molecules with the contribution of any one of the dissolved molecules. At a higher concentration. but still in the dilute region. the viscosity increases in a nonlinear manner with concentration due to the action of mutual hydrodynamic forces between molecules. The actual computation of the relative viscosity llR is done by taking the ratio of the energy dissipated by shear flow per unit time per unit volume by the solution to the corresponding quantity for the solvent alone. The various methods of carrying out the viscosity calculation for solute particles of different shapes and sizes have been reviewed by Frisch and Simha 1181. and the general result is that the concentration dependence of the viscosity can be written as:
(8.3)
in which <1J is the volume fraction and k1 is a shape-dependent constant: for rigid rods this constant has a value 0.73 1181.
