Enhanced Preservative Performance of Pine Wood through Nano-Xylan Treatment Assisted by High-Temperature Steam and Vacuum Impregnation.

This study used environmentally friendly nano-xylan to enhance the drug loading and preservative performance (especially against white-rot fungi) of pine wood (Pinus massoniana Lamb), determine the best pretreatment, nano-xylan modification process, and analyze the antibacterial mechanism of nano-xylan. High-temperature, high-pressure steam pretreatment-assisted vacuum impregnation was applied to enhance the nano-xylan loading. The nano-xylan loading generally increased upon increasing the steam pressure and temperature, heat-treatment time, vacuum degree, and vacuum time. The optimal loading of 14.83% was achieved at a steam pressure and temperature of 0.8 MPa and 170 °C, heat treatment time of 50 min, vacuum degree of 0.08 MPa, and vacuum impregnation time of 50 min. Modification with nano-xylan prohibited the formation of hyphae clusters inside the wood cells. The degradation of integrity and mechanical performance were improved. Compared with the untreated sample, the mass loss rate of the sample treated with 10% nano-xylan decreased from 38 to 22%. The treatment with high-temperature, high-pressure steam significantly enhanced the crystallinity of wood.

Effects of impulse-cyclone drying and silane modification on the properties of wood fiber/HDPE composite material.

Poplar fibers were pretreated under impulse-cyclone drying (ICD) and further modified by different types of silane with special chemical structures. The effects of ICD-assisted silane modification on the properties of wood plastic composites (WPCs) were investigated. The main findings indicated that the number of hydroxyl groups and the polarity of the fibers decreased after the ICD/silane co-modification, whereas the hydrophobicity and crystallinity of fibers, the compatibility and adhesion strength between fibers and plastics, and the mechanical properties, thermostability, and dynamic mechanical properties of WPCs were significantly improved. In this study, when the wood fibers were only modified by silane and the silane content was 5%, the WPCs had better properties, and the WPCs modified with vinyl tri-methoxysilane (A-171) had the best properties. Furthermore, the addition of a small amount of silane to the wood fibers modified by ICD provided even better physical and mechanical properties compared to those of the WPCs that were only modified by silane; when 3% silane was added, there were increases of 10.67%, 10.22% and 9.4%, in the tensile, flexural and impact strengths, respectively, and an increase of 6.84% in the contact angle of the composites. The water absorption rate of the composite significantly decreased as well.