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-  2018 

高温热处理对欧洲云杉和花旗松吸湿特性的影响

DOI: 10.13360/j.issn.2096-1359.2018.04.004

Keywords: 欧洲云杉, 花旗松, 木材吸附特性, 高温热处理, 等温吸附, GAB模型, 比表面积
Picea abies
, Pseudotsuga menziesii, wood sorption characteristics, high temperature heat treatment, sorption isotherms, GAB model, specific surface area

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Abstract:

研究了高温热处理对欧洲云杉和花旗松平衡含水率及吸湿特性的影响。采用水蒸气作为保护介质,设定160,180,200和220 ℃ 4个温度条件下进行高温热处理2 h,以双室温、湿度控制法获得等温吸附曲线,并采用GAB模型拟合,分析高温热处理对木材水蒸气等温吸附曲线线型、平衡含水率、有效比表面积的影响。结果表明:高温热处理可以显著降低2个树种试样的吸湿平衡含水率,处理温度越高,平衡含水率下降值越明显,220 ℃处理后试样的平衡含水率相较于未处理材的平衡含水率下降可达40%以上; 利用GAB吸附模型能够较好地描述高温热处理欧洲云杉木材和花旗松木材的等温吸附过程,等温吸附线拟合度较高(拟合度决定系数均高于0.98)。高温热处理并未改变木材等温吸附线的线型,高温热处理试样和未处理试样均呈现第2类等温吸附曲线特征,但热处理会影响等温吸附曲线斜率; 高温热处理后2个树种试样的有效比表面积显著降低,处理温度越高,有效比表面积下降值越明显,且试样高温热处理后比表面积相较于素材的下降比例与平衡含水率受高温热处理的影响相近。本研究可为热处理木材吸湿特性科学评价及实际高温热处理木材生产提供参考。
The effects of high temperature heat treatment on the equilibrium moisture content and sorption isotherms characteristics of Picea abies and Pseudotsuga menziesii were studied in this paper. In this study water vapor was employed as protective medium and the four heat treatment temperatures were pre-set, which were 160 ℃, 180 ℃, 200 ℃ and 220 ℃, respectively. The sorption experiments were performed in the two-chamber setup, the relative humidity of air was controlled by eight kinds of salt solutions and the air temperature of sorption experiments were constantly 25 ℃ during the whole isothermal adsorption process. The sorption isotherms of high temperature heat-treated wood were fitted by the Guggenheim-Anderson-deBoer(GAB)equation. The effects of high temperature heat treatment on the isothermal adsorption curve type, equilibrium moisture content and effective specific surface area were analyzed. The equilibrium moisture content of wood could be significantly reduced by the high temperature heat treatment, and the higher the treatment temperature, the greater the decreasing in the equilibrium moisture content. The equilibrium moisture content of the samples after 220 ℃ heat treatment were more than 40% lower than that of untreated samples. The GAB equation could be used to describe the isothermal adsorption curve of the high temperature heat treatment of wood, and the fitting accuracy is fairly high(R2>0.98 for all the samples). The isothermal adsorption linetype of wood did not be changed by the high temperature treatment. Both the high temperature heat treated samples and untreated samples exhibited the typeⅡisothermal adsorption linetype, but the slope of samples could be influenced by heat treatment. The effective specific surface area of the two species significantly reduced after heat treatment, and the higher the temperature, the more obvious the specific surface area decreases. The influence of the high temperature heat treatment on the decline proportion of the effective surface area were similar to the decline proportion of the equilibrium

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