The Synthesis and Properties of the Modified Bentonite-Starch Absorbent Polymer

The composite absorbent polymer was synthesized by the solution polymerization method with acrylic acid, starch and bentonite as raw materials, N, N-methylene-bis-acrylamide as cross-linking agent, and ammonium persulphate as initiator. The whole process was under nitrogen protection. Factors including amount of starch, crosslinker, initiator, monomer, and neutralization degree and reaction temperature were investigated in terms of their influences on water absorbency. Effect of bentonite amount on polymer strength and water absorption rate was also tested. The modified polymer, with the composition of 10% corn starch, 0.15% initiator, 0.05% crosslinking agent and 8% bentonite, showed a significant strength enhancement at 65°C and 80% neutralization degree (molar ratio) with water absorption of 1012g/g in deionized water and 92g/g in 0.9% NaCl solution.