Submitted to: Annual Meeting of the Bio Environmentally Degradable Polymer Society
Publication Type: Abstract Only
Publication Acceptance Date: July 9, 2002
Publication Date: September 10, 2002
Citation: WILLETT, J.L. PREPARATION OF STARCH-G-POLYACRYLAMIDE COPOLYMERS BY REACTIVE EXTRUSION. ANNUAL MEETING OF THE BIO ENVIRONMENTALLY DEGRADABLE POLYMER SOCIETY. 2002. Abstract p. 42. Technical Abstract: Graft copolymers of starch and polyacrylamide were prepared by reactive extrusion using a co-rotating twin screw extruder and ammonium persulfate initiator. Feed rates were 109 g/min up to 325 g/min (all components) at a moisture content of 50 percent, with screw speeds in the range 100 rpm to 300 rpm. Starch/monomer weight ratios ranged from 5:1 to 1.3:1. Conversions of monomer to polymer were generally 80 percent or greater with residence times of 400 seconds or less. Conversion was independent of residence time, and increased with feed rate, suggesting that reaction efficiency was proportional to the degree of fill in the extruder. Grafting efficiencies were in the range of 60 percent to 90 percent. Grafting efficiencies were lower for waxy maize starch than for normal corn starch. Solubilities in 70/30 water-ethanol (a polyacrylamide solvent) were approximately 10 percent to 15 percent by weight; polyacrylamide content of the soluble fractions ranged from 25 percent to 70 percent and increased with increasing acrylamide/starch ratio. Polyacrylamide molecular weights determined using intrinsic viscosity were in the range of 250,000 to 325,000. These results show that reactive extrusion offers the potential for rapid production of starch graft copolymers with unsaturated monomers.