Synthesis and characterization of novel cationic SCB hemicelluloses with a low degree of substitution

Novel cationic hemicelluloses from sugarcane bagasse were synthesized by quaternization with 3-chloro-2-hydroxypropyltrimethy-lammonium chloride (CHMAC) using sodium hydroxide as a catalyst in aqueous ethanol solution. The parameters including the molar ratio of NaOH/CHMAC (0.8-2.0), the molar ratio of CHMAC to anhydroxylose units in hemicelluloses (0.5-3.0), reaction time (0.5-2.5 h), and reaction temperature (50-80 degrees C) were optimized and the extent of quaternization was measured by yield and degree of substitution (DS). A CHMAC/hemicellulose molar ratio of 1.0 and a NaOH/CHMAC molar ratio of 1.2 were found to be an optimum condition for the reaction to proceed smoothly and to yield a product with an expected DS. The structure of the cationic hemicellulosic derivative was characterized by gel permeation chromatography (GPC), Fourier transform infrared (FT-IR), and C-13 nuclear magnetic resonance (NMR) spectroscopy as well as thermal analysis. It was found that the thermal stability and weight-average molecular weight of modified hemicelluloses decreased after chemical modification. (c) 2006 Elsevier Ltd. All rights reserved.