Acetylation and characterization of xylan from hardwood kraft pulp

Alkaline treatment of eucalyptus hardwood kraft pulp with 10% NaOH yielded 6–8% xylan. The acetylation of the extracted xylan was carried in DMAC/LiCl/pyridine system to obtain a series of xylan acetates with different degrees of substitution (DS). Structure elucidation of xylan and xylan acetate was obtained by 1H and 13C NMR spectroscopy and other homonuclear and heteronuclear 2D-NMR techniques. Inverse-gated 13C NMR was employed to determine the DS of xylan acetate. Furthermore, results also revealed equal reactivities at the C-2 and C-3 positions of xylan towards acetylation. Thermal stability, solubility behavior and nanofiber formation of xylan acetate were influenced by its DS values. The mechanical properties of xylan acetate propionate were also investigated.