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Chromatic variability of larch wood impacted by high-temperature thermal treatment and oil-wax coating(PDF)

Journal of Forestry Engineering[ISSN:2096-1359/CN:32-1862/S]

Issue:
2020 No.06
Page:
64-75
Research Field:
生物质能源与材料 执行主编:勇强 许凤
Publishing date:
2020-11-01

Info

Title:
Chromatic variability of larch wood impacted by high-temperature thermal treatment and oil-wax coating
Author(s):
ZHANG Jingyuan CHESNOKOVA Tatiana ZHANG Baoyuan ZHAN Jianfeng*
College of Material Science and Engineering, Northeast Forestry University, Harbin 150040, China
Keywords:
chromatic variability wood kiln-drying larch oilwax coating thermal treatment
PACS:
S781.43;S791.22
DOI:
10.13360/j.issn.2096-1359.202003012
Abstract:
In terms of aesthetical perception, color is one of the most fundamental physical properties of wood materials, and surface color differences have decisive influences over the customers acceptance of solid wood products. This study investigated the effect of thermal treatment and surface oilwax coating on the chromatic variability of larch wood. Green larch lumber samples were kilndried with conventional technology and further hightemperature thermally treated in atmospheric superheated steam conditions. Subsequently, the larch samples were surfacepainted with the transparent oilwax coating, and the colorimetric variables of the earlywood and latewood of specified larch samples were further determined separately by a specially designed image colorimetry method. The colorimetric variable differences between the earlywood and latewood were calculated, aiming at quantitatively analyzing the chromatic variability of larch earlywood and latewood in specified cases. Comparing with the kilndried samples, under the circumstance of N2 oilwax coating option and thermal treatment at 180 ℃ for 1 h, the saturation variable difference ΔS* between the earlywood and latewood increased by 60.8%, while the general colorimetric variable difference ΔE* remained at the same magnitude level. The variability mechanism behind the chromatic alterations of larch samples, induced by the combination of thermal treatment and surface oilwax coating, was proposed as the interaction between the existing chromogen groups and the newly emerging ones brought about by these technical processes. Due to the inhomogeneous distribution of resin contents inside each annual ring, the latewood tissue, which contains more resin canals than the earlywood, could act as the diffusion barrier for the oilwax compound and postpone the penetration of plant oils. In the light of this circumstance, the disrupt distribution behaviors of larch resins partially contributed to the chromatic variabilities between these two types of wood tissues. The test results demonstrated that a proper combination of thermal treatment and oilwax coating could be used for improving softwood colorimetric properties, enhancing the surface characteristics of larch wood, promoting it as a sustainable alternative wood resource.

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Last Update: 2020-11-11