Viscosity Characteristics of Cationic Polyacrylamide Aqueous Solutions

Area of Science:

• Polymer Science
• Rheology
• Materials Science

Background:

• Cationic polyacrylamide (CPAA) is widely used in industrial applications requiring fluid modification.
• Understanding CPAA solution rheology is crucial for optimizing performance under diverse conditions.
• High salinity and temperature environments pose significant challenges to polymer solution stability and flow behavior.

Purpose of the Study:

• To investigate the rheological properties of CPAA solutions.
• To evaluate the impact of CPAA concentration, shear rate, temperature, and electrolytes (NaCl, CaCl2) on viscosity and flow performance.
• To determine the critical shear rate for the transition from shear-thinning to shear-thickening behavior.

Main Methods:

• Utilized an Anton Paar rotational rheometer for flow behavior analysis.
• Tested CPAA solutions across a concentration range of 500-5000 ppm.
• Investigated temperatures from 20-80 °C at 20 °C intervals and electrolyte concentrations of 0-10 Wt.% NaCl and CaCl2.

Main Results:

• CPAA solutions exhibit non-Newtonian shear-thinning behavior below 200 s⁻¹, transitioning to shear-thickening above this rate.
• Dynamic viscosity significantly increases with CPAA concentration (e.g., 2.4 to 33.8 mPa·s for 500-5000 ppm at 10 s⁻¹).
• Viscosity decreases substantially with increasing temperature (e.g., 33.8 to 18.3 mPa·s for 5000 ppm at 10 s⁻¹ from 20 to 80 °C) and is reduced by NaCl and CaCl2 presence.

Conclusions:

• CPAA solutions demonstrate complex rheological behavior sensitive to concentration, shear rate, temperature, and electrolytes.
• The identified shear rate transition is critical for predicting flow performance in industrial settings.
• Findings provide valuable insights for optimizing CPAA formulations in challenging high-salinity and high-temperature applications.