Water sorption kinetics of superabsorbent hydrogels of saponified cassava starch-graft-poly(acrylamide)

Authors

  • Prabha C. Parvathy,

    1. Division of Crop Utilization, Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram, Kerala, India
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  • Alummoottil N. Jyothi

    Corresponding author
    1. Division of Crop Utilization, Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram, Kerala, India
    • Division of Crop Utilization, Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram, Kerala, India Fax: +91-471-2590063.
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Abstract

Superabsorbent polymers (SAPs) are hydrophilic polymeric networks that can absorb, swell and retain large quantity of water and other physiological fluids. In this paper, the water sorption pattern and kinetics of cassava starch based SAP hydrogels were studied under different conditions of swelling such as soaking duration, pH, presence of salts, and particle size of the hydrogel. The kinetics was studied using Voigt-based viscoelastic model to determine the rate parameter and the swelling rate (SR). It was noted that under all conditions, the water sorption followed a second order kinetics. The absorbency was directly proportional to the rate of swelling. But when the sample was allowed to swell in aqueous solutions of CaCl2 and AlCl3, the absorbency as well as the SR was irregular. The particle size also had significant effect on water absorption by the SAP and the polymer with smaller particles showed more absorption than those with larger particle size. The solvent induced phase transition of the superabsorbent hydrogel was also studied.

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