Effects of organification degree of mordenite on swelling behaviors of starch-g-poly (acrylic acid) /organo-mordenite superabsorbent composites

Abstract

Starch-g-poly(acrylic acid)/organo-mordenite (St-g-PAA/OMOR) superabsorbent composites were prepared via inverse suspension polymerizationutilizing potassium persulfate as an initiator and N, N’-methylene bisacrylamide as a crosslinker. Different dosages of cetyltrimethylammonium bromide were used to obtain organo-mordenite (OMOR) samples with different organification degrees. The effects of the organification degree of OMOR on the water absorbency, swelling behavior, and reswelling properties of St-g-PAA/OMOR were studied. The results from both FTIR and XRD analyses indicate that the Si–OH group of OMOR was involved in the formation of the St-g-PAA/OMOR composite. SEM analyses showed that the organification degree of OMOR influenced the morphology of the St-g-PAA/OMOR composite. The water absorption absorbency, swelling rate, and reswelling capability of the St-g-PAA/OMOR composite prepared using the OMOR with the optimal organification degree were superior to those of the St-g-PAA/mordenite composite. The swelling behaviors of the St-g-PAA/OMOR composites, which were measured in distilled water, obeyed Schott’s second-order kinetics model. The St-g-PAA/OMOR composite prepared using the OMOR with the 8 wt.% organification degree had the highest water absorption capacity and the highest swelling rate. Moreover, after five swelling–shrinking cycles, the composite retained its excellent water absorption capacity.