蒸汽介质热处理对毛白杨木材颜色的影响

以毛白杨木材为研究对象,采用蒸汽介质热处理方法在氧气含量低于2%的密闭容器中以温度170～230℃、时间1～5h的处理条件对其进行热处理。结果表明:随着处理温度的升高和处理时间的延长,色饱和度差ΔC*逐渐减小、色差ΔE*和色相差ΔH*逐渐增大,说明热处理后木材的颜色由原色逐步过渡到深褐色。方差分析和多重比较结果表明:热处理温度比热处理时间对毛白杨木材颜色变化的影响更为重要。此外,进一步得出了色差值与热处理温度、时间三者之间的回归模型。利用此特性,对一些浅色木材进行热处理,可赋予其凝重的颜色,同时还可增强其尺寸稳定性,从而提高其产品附加值,扩大应用领域。

Effect of Steam Heat Treatment on Color of Chinese White Poplar Wood

Steam heat treatment can darken wood color remarkably. There is a highly relativity among the color change degree, heat treatment time and temperatures. The specimens of Chinese White Poplar (Populus tomentosa) was steam heat- treated in an airtight equipment with an atmosphere within comprising less than 2 percent oxygen content at temperatures from 170 to 230 ℃ for time from 1 to 5 hours, respectively. Saturated steam was used as a heating medium and a shielding gas. The results showed that the chroma difference (ΔC* ) was decreased gradually while the color difference (ΔE* ) and hue difference (ΔH* ) were increased with the increase of temperature and the extension of treatment time. This indicated that the color of steam heat-treated wood became darker and darker compared with original color. Compared with treatment time, treatment temperature played a more important role to change the color of heat-treated wood during the process of heat treatment according to the results of ANOVA and multiple comparison analysis. Additionally, the regression models among the color difference, treatment temperatures and times were established. The results suggested that the better color of wood could be obtained after steam heat treatment compared with original color as well as the dimensional stability would be improved. Therefore, the value of the timber could be increased and the application fields could be extended after the steam heat treatment.