Preparation of cassava starch-graft-polyacrylamide superabsorbents and associated composites by reactive blending

Cassava starch-g-polyacrylamide (PAM) was successfully prepared by a reactive batch processing using a specially designed batch reactor resulting in a superabsorbent polymer (SAP) with water absorption of 605 g/g being obtained under the optimized reaction conditions. The occurrence of a graft copolymer was confirmed by FT-IR spectra, where it was found to exhibit all characteristic bands of both starch and acrylamide (AM) units. SEM micrographs of the starch granules showed an irregular shape and varied particle sizes with a smooth surface, while the graft copolymers had a coarse porous structure and broad network. Various types of inorganic filler were added to the graft copolymer to prepare the SAP composites (SAPC). It was found that the SAPC with bentonite clay exhibited the highest water absorption of approximately 730 g/g. Conversely, the incorporation of silica to the graft copolymer gave a significantly lower water absorption capability than the copolymer alone.