Superabsorbent Composite XXII: Effects of Modified Sepiolite on Water Absorbency and Swelling Behavior of Chitosan-g-Poly(acrylic acid)/Sepiolite Superabsorbent Composite

In this work, a series of chitosan-g-poly(acrylic acid)/sepiolite (CTS-g-PAA/ST) superabsorbent composites containing raw sepiolite, acid-activated sepiolite, and cation-exchanged sepiolite were synthesized by free-radical graft polymerization in aqueous solution, using N,N'-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The effects of raw sepiolite, acid-activated sepiolite, and cation-exchanged sepoilite on equilibrium water absorbency, swelling rate, and swelling behavior in different pH value solution of superabsorbent composites were systematically investigated. The results from FTIR spectra showed that chitosan and sepiolite participated in graft polymerization reaction with acrylic acid. The introduction of acid-activated and cation-exchanged sepiolite into chitosan-g-poly(acrylic acid) polymeric network could improve water absorbency and swelling rate compared with that of the raw sepiolite. All prepared samples have similar swelling behavior in different pH solutions and the equilibrium water absorbencies of samples keep roughly constant in the PH range from 4 to 12. POLYM. COMPOS., 31:89-96, 2010. (C) 2009 Society of Plastics Engineers.