Flow behaviors of anionic polyacrylamide aqueous solutions

This experimental study investigates the flow behaviors of anionic polyacrylamide (APAA) aqueous solutions to better understand their characteristics for different industrial uses and applications. This study examined numerous experimental samples of polymer solutions using FLOC 24 APAA powder over concentration range of 500-5000 mg/L, and two different electrolytes of NaCl and CaCl 2 were included with concentration range of 1-10 Wt. %. To scrutinize the flow behavior of APAA aqueous solutions, rheological measurements of shear stress and dynamic viscosity versus shear rate were carried out employing MCR 92 rotational rheometer over four temperatures of 20, 40, 60, and 80 °C. The main outcomes of the current study include, firstly, the shear stress increases with both shear rate and APAA concentration. The effect of polymer concentration is mostly notable at shear rate of less than 200 s -1 , above this verge, the shear stress contours are similar regardless of APAA concentration. Secondly, the rheogram contours decline significantly as the temperature rises from 20 °C to 80 °C, attributed to negative thermal effects on molecular cohesion forces of APAA solutions. The APAA solutions generally exhibit shear-thinning behavior up to a critical shear rate, after which a shear-thickening behavior is observed. Thirdly, temperature has a strong negative influence on the reported dynamic viscosity across the tested range of 20 °C to 80 °C. Lastly, the introduction of varying concentrations of NaCl and CaCl₂ salinity consistently leads to a reduction in dynamic viscosity of APAA polymer solutions.