BEHAVIOR OF THE SOLUTIONS OF HYDROLYZED P OLYACRYLAMIDE IN SHEAR AND CONVERGING FLOWS

Viscosity of semidilute aqueous solutions of high-molecular-mass polya crylamide was examined as a function of velocity gradient in shear flo w in a cylinder-in-cylinder cell and in converging flow at the inlet o f a narrow capillary. It was demonstrated that in shear flow, the visc osity decreased with an increase in velocity gradient, whereas the eff ect of velocity gradient was the opposite in the case of intensely con verging flow. Decreasing polymer concentration in solution or adding s alt reduced these effects. Viscosity variation is controlled by two co mpeting processes: deterioation of the fluctuation network in semidilu te solution and uncoiling of macromolecules. In an intensely convergin g flow, chain uncoiling was found to dominate.