Preparation and swelling properties of crosslinked sodium polyacrylate

Crosslinked sodium polyacrylate as a superabsorbent was prepared by inverse suspension polymerization with cyclohexane as the continuous phase and sorbite anhydride monostearic acid ester (span-80) as the dispersant. The crosslinking degree was regulated by NaOH. The distilled water absorbency (WA) of the polymer gel was about 700 times its own weight if the gel was allowed to swell at room temperature for 24 h. WA under various conditions, such as varying pH, temperature, reaction time, neutralization, and cyclohexane concentration, was investigated and optimized. Our results revealed that the optimal reaction conditions were 55 degreesC, 25-min reaction time, 85% neutralization, and a 7:1 (v/v) cyclohexane/monomer ratio. Our results also showed that such synthesized polymer gels have a high WA and a good water-retention ability under different pressures. (C) 2001 John Wiley & Sons, Inc.