Synthesis and swelling behavior of a novel protein-based superabsorbent hydrogel composite:: Collagen-g-poly (sodium acrylate)/kaolin

This article describes the synthesis and swelling properties of a superabsorbing hydrogel composite based on collagen. The composite have been prepared via graft copolymerization of acrylic acid (AA) in the presence of kaolin powder using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. The certain variables of the graft copolymerization (i.e. the monomer, the initiator, and the crosslinker concentration as well as kaolin/collagen weight ratio) affected on the ultimate water-swelling capacity were optimized. Evidence of grafting and kaolin interaction was obtained by comparison of FTIR spectra of initial substrates and superabsorbent composite. The effect of kaolin amount and MBA concentration showed that with increasing of these parameters, the water absorbency of the superabsorbent composite was decreased. The swelling measurements of the hydrogels were conducted in aqueous salt solutions. The effect of solutions with different pHs on the swelling of the superabsorbent was also studied. Finally, the swelling kinetics of the synthesized composite with various particle sizes was preliminarily investigated