Starch graft copolymers as superabsorbents obtained via reactive extrusion processing

Starch graft copolymers have been obtained via grafting of acrylic monomers i.e. acrylamide (AAm) and acrylic acid (AA) during the reactive extrusion processes. 2,2'-azobis (2-methylpropionamidine) dihydrochloride (AAPH) was used as a radical initiator and N'N-methylenebisacrylamide (MBA), mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (trade name PETIA) and alkoxylated pentaerithritol acrylate (trade name Ebecryl 40) were applied as acrylic crosslinkers. The obtained materials were characterized by FTIR and their water sorption properties investigated using swelling (vol. %) and sorption (wt. %) tests. Sorption of water into these graft copolymer samples reached values of ca. 6 - 13 g of water per g of dry materials. It was also found that water sorption values were dependent on ratio of AAm and AA as well as on a type of the applied crosslinking agent.