Effects of modified vermiculite on the synthesis and swelling behaviors of hydroxyethyl cellulose-g-poly(acrylic acid)/vermiculite superabsorbent nanocomposites

A series of hydroxyethyl cellulose-g-poly(acrylic acid)/vermiculite (HEC-g-PAA/VMT) superabsorbent nanocomposites were prepared by radical solution polymerization among hydroxyethyl cellulose (HEC), partially neutralized acrylic acid (AA), raw vermiculite (RVMT), acidified vermiculite (AVMT) and organo-vermiculite (OVMT) in the presence of initiator ammonium persulfate (APS) and crosslinker N,N’-methylenebisacrylamide (MBA). FTIR results revealed that AA was grafted onto HEC backbone and VMT participated in polymerization. VMT was exfoliated during polymerization reaction and a nanocomposite structure was formed as shown by XRD and TEM analysis. Effects of VMT content, concentration of HCl solution and organification degree of OVMT on water absorbency were investigated and the swelling kinetics of the developed nanocomposites was also evaluated. Results showed that incorporation of VMT greatly enhanced the water absorbency, and the modified VMT by acidification and organification can improve the water absorbency more remarkably than raw one. OVMT can improve the swelling capabilities and swelling rate to the highest degree in contrast to RVMT and AVMT.