The effect of metal ions additives on the rheological behavior of polyacrylamide solution

Abstract

The rheological behavior of polyacrylamide solution has been studied here in the presence of various metal ions using a concentric cylinder viscometer. Determining shear stress in the shear rate range 0–555 s −1 has provided empirical measures of the stabilization effect of the metal ions. It was found that greater shear stress of the polymer solution occurs in the presence of metal ions than with pure polyacrylamide solution. The effect of temperature and of the kind of metal ions on the rheological behavior of polyacrylamide–metal solution was systematically studied by using the power equation in the temperature range 20–50 °C and at polyacrylamide concentration of 0.5 wt%. The consistency coefficient of polyacrylamide–metal solution decreased and the flow behavior index of polyacrylamide–metal solution increased with increasing temperature. It was found that the effect of temperature on the consistency coefficient and flow behavior index of polyacrylamide–metal solution followed an Arrhenius type relationship. For metal ions, the stabilizing effect as measured by the difference in consistency and flow behavior index between polymer and metal ions, was proportional to the radius of the metal ion, suggesting that the strength of the complex between the ion and polymer is important in determining stability. Transition metal ions showed dependence of the stabilizing effect on ionic radius. The general rheological equation, optimal in terms of multiple correlation coefficients, was established and confirmed by experimental data.