Effects of decreasing carbohydrate content on properties of wood strands

Hot-water pretreatment was performed on wood strands to investigate effects of the extraction of hemicellulose under different temperature (140, 155, and 170 A degrees C) and time durations (30 and 60 min) conditions. Hydrolysate was analyzed by means of high-performance liquid chromatography. Chemical changes in the surface of wood strands were studied by infrared spectroscopy. The effects of hemicellulose extraction on the wettability of wood strands were studied by measuring the contact angle and surface free energy. The mechanical properties of wood cell walls before and after treatment were studied by nanoindentation. Among the extracted monosaccharides, mannose was found in the highest concentration. The mechanical properties of cell walls showed little decrease after extraction. The chemical changes in the surface of the wood strands reduced wettability of wood surface by water and produced hydrophobic characteristics after extraction.