The objective of this study was to determine the technology of chemical modifying and multilayer hot-press drying on poplar wood. The chemicals were impregnated into cell lumen space by pulse-dipping machine to improve the dimension stability and mechanical property of timber. The timbers were compressed and dried by the multilayer hot-press drying to increase the density of timber. Results indicate that the physical and mechanical properties were compared between modified timber and natural timber. Based on the findings, the results demonstrated that the density of modified wood improves by 58.1 %, the hardness of the end profile surface improves by 66.6 %, while tangential direction 210 % and radial 160 %, the bending strength improves by 77.8 %, the bend elastic modulus improves by 66.3 %. The improvements of mechanical property were owed to the reinforcement of chemical on the cell wall and lumen space of wood. Characteristics of Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) for modifying were studied using FTIR spectrometer and XRD instrument. The intensity of hydroxyl absorption peak in the infrared absorption spectrogram decreased significantly, and that of carbonyl decreased lightly. The C=O absorbance at 1750 cm-1 reduced as result of the deacetylation of hemicelluloses and reaction between C=O and -NHCH2OH of urea-formaldehyde prepolymer.. The crystallinity of wood decreased lightly from 39.65 % to 37.06 %. Fourmorphologic models of chemical within wood were discovered by SEM.

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