Study of the flow development of polymer solutions through capillaries

Flow experiments through capillaries with semirigid and rigid polymers in aqueous solutions were carried out in order to study the dependence of the flow development on the molecular conformation and the length to diameter ratio (L/D), oC the capillary at relatively low shear rates. It was found that the apparent viscosity has a strong dependence upon the ratio L/D for a given shear rate, although an asymptotic value is reached. This dependcnce was reflected in the non-linearity of Bagley's plots. The asymptotic value was attained at lower L/D values for semirigid molecules than for rigid ones, showing the influence of the molecular conformation on the flow field development due to the different modes of relaxation for each type of molecule.