Abstract
Graft polymerizations of acrylonitrile onto both a commercial larchwood hemicellulose and a purified (low lignin) wheat straw hemicellulose could be initiated by ceric ammonium nitrate. The resulting hemicellulose‐g‐polyacrylonitrile (PAN) copolymers were fractionated by extraction at room temperature with dimethylformamide and dimethylsulfoxide. Fractions were characterized by determining both the wt % PAN in each polymer fraction and the molecular weight of grafted PAN. Saponification of the PAN component of hemicellulose‐g‐PAN gave a water‐dispersible graft copolymer with good thickening properties for water systems. An absorbent polymer, similar to the starch‐based absorbents (Super Slurpers), was produced when saponified hemicellulose‐g‐PAN was isolated by methanol precipitation and then dried. Larchwood hemicellulose was also graft‐polymerized with methyl acrylate using ceric ammonium nitrate initiation, and the hemicellulose‐g‐poly(methyl acrylate) was extrusion‐processed into a tough, leathery plastic. Although ceric ammonium nitrate could be used as an initiator for graft polymerizations onto low‐lignin hemicelluloses, it was inert with crude wheat straw hemicellulose containing 11% lignin. The ferrous sulfate–hydrogen peroxide redox system was used to initiate graft polymerizations onto this high‐lignin material, and properties of the resulting hemicellulose‐g‐poly(methyl acrylate) and saponified hemicellulose‐g‐PAN graft copolymers were evaluated.