Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2004
Publication Date: 8/22/2004
Citation: Willett, J.L., Finkenstadt, V.L. Processing and properties of starch-polyacrylamide graft copolymers prepared using reactive extrusion. 2004. p.44.
Technical Abstract: Graft copolymers of starch and polyacrylamide (PAAm) can be readily prepared using a twin screw extruder. Initiator type and concentration significantly affect the properties of the PAAm. Ammonium persulfate (APS) gives PAAm with molecular weights exceeding 500,000, while Fenton's reagent (ferrous iron-hydrogen peroxide) gives molecular weights in the range 75,000 to 300,000 under comparable conditions. APS also gives higher conversions of monomer to polymer (less than 90%) and higher grafting efficiencies (approximately 75%) than Fenton's reagent. Effects of increasing monomer content and decreasing initiator content are in general agreement with free radical polymerization kinetics. PAAm molecular weights are lower with Fenton's reagent due to chain termination by ferric ions. Since grafting PAAm molecular weight and graft frequency both depend on the level of initiator used, some degree of control over the properties of the starch graft copolymer is possible. After saponification, the starch-PAAm graft copolymers absorb between 150 and 250 times their weight in water at pH7.