Preparation of a starch-graft-acrylamide/kaolinite superabsorbent composite and the influence of the hydrophilic group on its water absorbency

A novel starch-graft-acrylamide/kaolinite superabsorbent composite with water absorbency 4000 times (g g(sample)(-1)) was synthesized by a graft copolymerization reaction among acrylamide, potato starch and kaolinite ultrafine powder, followed by saponification with NaOH. The influence of the hydrophilic group on water absorbency was investigated. It was found that the combined absorbent effect of -CONH2, -COONa and -COOH groups was superior to that of a single group, and the composite with the molar ratio of 8:63 for the -CONH2, -COONa and -COOH groups exhibits the highest water-absorbent ability. (C) 2003 Society of Chemical Industry.