Zero-shear Viscosity and Critical Concentrations of Aqueous Solution of Partially Hydrolyzed Polyacrylamide

Creep and oscillation experiments were performed to measure the zero-shear viscosity (eta(0)) and storage modulus (G') of aqueous solution of partially hydrolyzed polyacrylamide (PHPA), respectively. The overlapping concentration (C*) and crossover concentration (C**) of PHPA solution were determined through the dependence of no on solution concentration( C). Effects of temperature, pH value and electrolytes (NaCl and CaCl2) on C* and C** were investigated. The results show that as temperature and electrolyte concentration are raised, eta(0) and G' decrease while C* and C** increase gradually. The higher the electrolyte cation valence is, the more obvious the induced variation of viscosity and critical concentrations of PHPA solution is. With pH value increasing, eta(0) and G' increase initially and decrease subsequently while C* and C** decrease first and increase afterwards.