Monitoring the Cross-Linking of a HPAm/Cr(III) Acetate Polymer Gel Using1H NMR, UV Spectrophotometry, Bottle Testing, and Rheology

The gelation of a polymer gel formulated at 40°C with 7500 mg/L of partly hydrolyzed polyacrylamide (HPAm) and 3000 mg/L of Cr(III) acetate 50% active was monitored for 72 h using 1H nuclear magnetic resonance (NMR) techniques, oscillatory rheology, bottle testing, and UV spectrophotometry. During the first 5 h, 1H NMR techniques detected changes in the polymer gel signal intensity and transverse relaxation that may be related to the rheological properties of the HPAm/Cr(III) acetate polymer gels. Bottle testing and UV spectrophotometry detected additional changes during 30 and 72 h respectively. Monitoring of the gelation process using these techniques is presented here.