Toward improved understanding of the cell-wall density and porosity of wood determined by gas pycnometry
Toward improved understanding of the cell-wall density and porosity of wood determined by gas pycnometry
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DOI：
10.1007/s00226-013-0568-1
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发表时间：
2013-07
影响因子：
3.4
通讯作者：
M. Zauer;A. Pfriem;A. Wagenführ
中科院分区：
文献类型：
--
作者：
M. Zauer;A. Pfriem;A. Wagenführ
本研究的主要目的是利用气体比重法评估样品制备对细胞壁密度和孔隙度的影响。挪威云杉（Picea abies(L.)）原生和热改性双株样品分析了岩溶、槭槭（Acer pseudoplatanusL.）和欧洲白蜡树（Fraxinus excelsiorL.）。这些样本在形状、几何形状和气候状态方面各不相同。一方面，样品像往常一样被烤箱干燥，另一方面，在22°C和95%的相对湿度条件下。采用溶剂交换干燥法对样品进行处理。除氦气外，还使用了氮气作为置换气体。试验首先表明，这可能导致对气体比重测定的木材细胞壁密度或孔隙度的误解。结果表明：原生云杉的细胞壁密度低于原生枫和灰分，孔隙率高于原生枫和灰分；由于热改性，细胞壁密度降低。研究表明，确定的细胞壁密度和孔隙率的木材强烈依赖于样品的几何形状和气候状态。在22°C和95%相对湿度条件下，所有被调查树种的细胞壁密度明显高于烘箱干燥的细胞壁密度。
The main objective of this study was to evaluate the effect of sample preparation on cell-wall density and porosity using gas pycnometry. Native and thermally modified twin samples of Norway spruce (Picea abies(L.) Karst.), sycamore maple (Acer pseudoplatanusL.), and European ash (Fraxinus excelsiorL.) were analyzed. The samples differed in terms of shape, geometry, and climatic state. On the one hand, the samples were oven dry as usual and, on the other hand, conditioned at 22 °C and 95 % relative humidity. Furthermore, the samples were processed using solvent exchange drying. In addition to helium, nitrogen was used as a displacement gas. The tests show i.a. how this can lead to misinterpretation of the cell-wall density or porosity of wood determined by gas pycnometry. The results show that native spruce has a lower cell-wall density and higher porosity compared with native maple and ash. Due to thermal modification, the cell-wall densities are decreased. The investigations show that the determined cell-wall density and porosity of the wood are strongly dependent on the sample geometry and climatic state. The cell-wall densities of all investigated wood species in the conditioned state at 22 °C and 95 % relative humidity are significantly higher compared with the oven-dry cell-wall densities.