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Reactive Extrusion of Starch‐Polyacrylamide Graft Copolymers: Effects of Monomer/Starch Ratio and Moisture Content
Author(s) -
Finkenstadt Victoria L.,
Willett Julious L.
Publication year - 2005
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200500157
Subject(s) - starch , acrylamide , polyacrylamide , monomer , copolymer , extrusion , chemistry , moisture , water content , polymer chemistry , reactive extrusion , food science , polymer , materials science , organic chemistry , composite material , geotechnical engineering , engineering
Summary: The effects of monomer/starch feed ratios and moisture content during reactive extrusion of starch‐polyacrylamide graft copolymers were investigated. Acrylamide/starch ratios ranged from 0.20 to 1.87 at 50% moisture content, while moisture content was increased from 45 to 75% with an acrylamide/starch ratio of 0.33. Average conversion was 86.6% (±3.5%), independent of monomer content, at acrylamide/starch ratios of 0.77 and less. Conversion increased to approximately 95% when the acrylamide/starch ratio exceeded unity. Molecular weight of grafted polyacrylamide increased as the acrylamide/starch ratio increased. Graft efficiency was constant at approximately 75% for monomer/starch ratios of 0.77 or less, and decreased to 52.3% as the monomer/starch ratio increased to 1.87. Higher acrylamide/starch ratios gave more frequent grafts of higher molecular weight. As moisture content decreased from 75 to 45%, conversion and graft content increased from 78 and 14% to 97 and 23%, respectively. Lower moisture content gave fewer grafts of higher molecular weight. Ungrafted polyacrylamide homopolymer increased with monomer/starch ratio and moisture content. These results indicate that graft copolymer properties can be controlled through the monomer/starch ratio and moisture content during reactive extrusion.Molecular weight distributions of grafted polyacrylamide at different moisture contents during extrusion: A) 75%; B) 65%; C) 55%; D) 45%.