Synthesis and Characterization of Poly(Acrylamide-co-2-Acrylamido-2-Methylpropane Sulfonic Acid)/Kaolin Superabsorbent Composite

A novel poly(acrylamide-co-2-acrylamido-2-methylpropane sulfonic acid)/kaolin (P(AM-co-AMPS)/kaolin) superabsorbent composite was synthesized by copolymerization reaction of acrylamide (AM), 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and kaolin using ammonium persulfate (APS) as an initiator and N,N’-methylenebisacrylamide (NMBA) as a crosslinker in an aqueous solution. Evidence of the reaction between kaolin and P(AM-co-AMPS) copolymer was confirmed by comparing the Fourier transform infrared (FTIR) spectra of kaolin, P(AM-co-AMPS) copolymer and P(AM-co-AMPS)/kaolin superabsorbent composite. The reaction was also confirmed by scanning electron microscopy (SEM). Effects of APS, NMBA and kaolin concentrations, weight ratio of AM/AMPS and reaction temperature on water absorbency were investigated. The superabsorbent composite synthesized under the optimum synthesis conditions exhibits the maximum water absorption of 1678 g/g in distilled water and 141 g/g in 0.9 wt% NaCl solution. Results obtained from this study show that P(AM-co-AMPS)/kaolin superabsorbent composite has good water and salt solution absorbency at a relatively high temperature. The gel strength of the superabsorbent composite is significantly increased by increasing the concentration of kaolin.