Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/15/2004
Publication Date: 7/12/2004
Citation: Willett, J.L., Finkenstadt, V.L. Reactive extrusion of starch:continuous production of starch graft copolymers. Abstract n. 41-3. p. 102.
Technical Abstract: The preparation of starch graft copolymers using water-soluble monomers by the standard batch-slurry method is generally limited due to monomer solubility in the reaction medium. We have recently demonstrated the use of reactive extrusion as a continuous method of producing starch-polyacrylamide graft copolymers. Parameters investigated include acrylamide/starch ration, moisture content, and type and concentration of initiator. Typical residence times were 400 seconds or less. In general, conversions of monomer to polymer are 90 per cent or greater, with grafting efficiencies of approximately 70 per cent for acrylamide/starch feed ratios of 0.8 or less. Moisture content has a significant effect on conversion, grafting efficiency, and molecular weight of polyacrylamide; these parameters decrease as the moisture content increases. Ammonium persulfate is an effective initiator in this process at levels as low as 0.25 per cent based on starch. Other initiators studied (ferrous ammonium sulfate/hydrogen peroxide or ceric ammonium nitrate) were not as effective, yielding lower conversion, grafting efficiencies, and polyacrylamide molecular weights. These materials have potential applications as hydrogels, controlled release agents, and flocculants.