Enzymatically Debranched Xylans in Graft Copolymerization.

Wheat arabinoxylan was treated with two α-arabinofuranosidases exhibiting different mode of action to create three different polymeric substrates. These three substrate preparations were characterized by xylopyranose backbone sugars that are (1) singly substituted by arabinose at C2 or C3, (2) doubly substituted by arabinose at C2 and C3, and (3) largely unsubstituted. All xylan preparations were grafted with glycidyl methacrylate using cerium ammonium nitrate and then evaluated in terms of graft yield and adsorption to cellulose surfaces.

Effect of xylan structure on reactivity in graft copolymerization and subsequent binding to cellulose.

The grafting reactivities with glycidyl methacrylate (GMA) of five xylans from hardwood and cereal sources were compared. The structural property that best predicted the reactivities of xylans with GMA was the fraction of 4-O-methylglucuronic acid (MeGlcA) substitution. A comparatively high level of arabinose substitution was also positively correlated to reactivity with GMA.

Determination of surface-accessible acidic hydroxyls and surface area of lignin by cationic dye adsorption.

A new colorimetric method for determining the surface-accessible acidic lignin hydroxyl groups in lignocellulose solid fractions was developed. The method is based on selective adsorption of Azure B, a basic dye, onto acidic hydroxyl groups of lignin. Selectivity of adsorption of Azure B on lignin was demonstrated using lignin and cellulose materials as adsorbents.

Network formation of nanofibrillated cellulose in solution blended poly(methyl methacrylate) composites.

Composites of poly(methyl methacrylate) (PMMA) and nanofibrillated cellulose (NFC) were prepared by solution blending and further processed by injection and compression molding. To improve adhesion at the PMMA/NFC interface, the nanofibrils were covalently grafted with PMMA. Formation of a percolating nanofibril network was observed between 1 and 5 wt.