Rheological properties of hydrolyzed polyacrylamide/sodium oleate mixed system in the presence of different inorganic salts

• The effect of salts with the same anions but different cations was studied.
• All systems show shear-thinning property at higher shear rate.
• In oscillatory experiments, all of the systems show elastic behaviors.
• The effectiveness of cations decreasing the viscosity is Na+>K+>12Ca2+>12Mn2+.

The effects of inorganic salts NaCl, KCl, CaCl2 and MnCl2 with the same anions but different cations on the rheological properties of hydrolyzed polyacrylamide/sodium oleate (HPAM/C17H33COONa) mixed system were investigated systemically by steady-flow and oscillatory experiments at different concentrations of inorganic salts and temperatures, respectively. The results of steady-flow measurements indicate that for all of the systems, the steady-shear viscosities (η) decrease obviously with the addition of inorganic salts and show shear-thinning property at higher shear rate and the data fit power-law equation. In oscillatory experiments, all of the systems show elastic behaviors which also depend strongly on the concentrations of the inorganic salts. The storage moduli (G'), loss moduli (G″), the complex viscosities (η⁎) and η all decreased as the inorganic salts concentrations increased. The order of effectiveness of cations in decreasing the viscosity and the activation energy of HPAM/C17H33COONa mixed system is Na+>K+>12Ca2+>12Mn2+.