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不同含水率状态下木材细胞壁孔径分布变化

仲翔 张少军 马尔妮

仲翔, 张少军, 马尔妮. 不同含水率状态下木材细胞壁孔径分布变化[J]. 北京林业大学学报. doi: 10.12171/j.1000-1522.20210260
引用本文: 仲翔, 张少军, 马尔妮. 不同含水率状态下木材细胞壁孔径分布变化[J]. 北京林业大学学报. doi: 10.12171/j.1000-1522.20210260
Zhong Xiang, Zhang Shaojun, Ma Erni. Variation in pore size distribution of wood cell wall under different moisture states[J]. Journal of Beijing Forestry University. doi: 10.12171/j.1000-1522.20210260
Citation: Zhong Xiang, Zhang Shaojun, Ma Erni. Variation in pore size distribution of wood cell wall under different moisture states[J]. Journal of Beijing Forestry University. doi: 10.12171/j.1000-1522.20210260

不同含水率状态下木材细胞壁孔径分布变化

doi: 10.12171/j.1000-1522.20210260
基金项目: 国家自然科学基金项目(31971583)
详细信息
    作者简介:

    仲翔。主要研究方向:木材物理学。Email:ZVita@hotmail.com 地址:100083 北京市海淀区清华东路35号北京林业大学材料科学与技术学院

    责任作者:

    马尔妮,博士,副教授。主要研究方向:木材物理、木材保护与改性。Email:maerni@bjfu.edu.cn 地址:同上

  • 中图分类号: S781.33

Variation in pore size distribution of wood cell wall under different moisture states

  • 摘要:   目的  探究由水分所引发的木材细胞壁孔隙结构变化规律与机制,为木材的热质转移、木材的渗透性与木材改性提供理论指导。  方法  将杨木和杉木制成5 mm(径向) × 5 mm(弦向) × 1 mm(轴向)的木片,基于氮气吸附法、差示扫描热孔计法考察试样在绝干状态、气干状态、纤维饱和状态和饱水状态4种典型水分状态下的孔径分布、比表面积、孔体积等特征参数,并对比不同状态及不同树种间的孔隙结构差异。  结果  木材细胞壁孔径大多在10 nm以下,尤其以4 nm以下为主,10 nm以上孔隙相对较少;随着含水率的提升,木材细胞壁孔径分布曲线显著升高,从气干状态到纤维饱和状态,杨木和杉木的孔径分布最大值分别增加了52.73%和58.62%,而从纤维饱和状态到饱水状态,二者分别增加了435.24%和470.43%。  结论  在木材由绝干状态逐渐吸湿,以及吸水至饱水状态的过程中,木材细胞壁孔隙体积呈明显增大趋势。在木材达到饱水状态后,细胞壁孔隙体积增大至极限,但由于自由水的冰点下降,其在−2 ℃左右产生大量吸热信号进而干扰测量结果,故此时差示扫描热孔计法所测得的孔径分布参考范围有限。不同树种间孔隙分布差异不明显。

     

  • 图  1  绝干状态杨木与杉木氮气吸附与脱附等温线

    Figure  1.  Nitrogen adsorption and desorption isotherms of poplar and fir in the dry state

    图  2  绝干状态下杨木与杉木细胞壁孔径分布

    Figure  2.  Pore size distribution of poplar and fir cell wall at oven-dry state

    图  3  DSC测试所得杨木与杉木细胞壁孔径分布

    Figure  3.  Pore size distribution of poplar and fir cell wall obtained by DSC

    图  4  10 nm以下杨木与杉木细胞壁孔径分布

    Figure  4.  Pore size distribution of poplar and fir cell wall below 10 nm

    图  5  10 nm以下杨木与杉木细胞壁累计孔径分布

    Figure  5.  Cumulative pore size distribution of poplar and fir cell wall below 10 nm

    图  6  30 nm以下木材细胞壁累计孔径分布

    Figure  6.  Cumulative pore size distribution of wood cell wall below 30 nm

    表  1  经处理后的试样含水率

    Table  1.   Moisture content of the sample after treatment %

    试样
    Sample
    气干状态
    Air-dry state
    纤维饱和状态
    Fiber saturation state
    饱水状态
    Saturated state
    杨木 Poplar1323180
    杉木 Fir1220283
    下载: 导出CSV

    表  2  不同孔径对应的温度及保温时间

    Table  2.   Temperature and holding time corresponding to different pore sizes

    孔径
    Pore
    size/nm
    温度
    Temperature/℃
    保温时间 Constant temperature time/min
    气干状态
    Air-dry
    state
    纤维饱和状态
    Fiber saturation
    state
    饱水状态
    Saturated
    state
    1.6−40.0885
    1.8−30.0333
    2.5−21.0332
    4.0−11.6332
    6.0−7.3333
    7.9−5.4333
    10.0−4.2333
    14.7−2.8334
    20.4−2.0335
    31.1−1.3338
    50.1−0.83312
    99.6−0.43316
    396.6−0.13320
    10.0333
    下载: 导出CSV

    表  3  杨木与杉木氮气吸附孔隙结构参数

    Table  3.   Pore structure parameters of poplar and fir obtained by nitrogen adsorption

    树种 Tree speciesSBET/(m2·g−1)Da/nmVa/(mm3·g−1)Dd/nmVd/(mm3·g−1)
    杨木 Poplar5.6191.94933.702.20335.35
    杉木 Fir8.5051.94922.862.18224.52
    注:SBET为BET测得的孔隙比表面积(m2/g);DaDd分别为吸附和解吸曲线计算的平均孔径(nm);VaVd分别为吸附和解吸曲线计算的平均孔体积(mm3/g)。Notes: SBET is the pore specific surface area measured by BET; Da and Dd are the average pore size calculated by the adsorption and desorption curves respectively; Va and Vd are the average pore volume calculated by the adsorption and desorption curves.
    下载: 导出CSV

    表  4  4种典型水分状态下杨木与杉木孔径分布差异显著性检验

    Table  4.   Significance test of difference in pore size distribution between poplar and fir under four typical water states

    水分状态
    Water state
    t
    t-value
    双尾t临界值
    t critical two-tail
    双尾p
    P value of two-tail
    绝干状态
    Oven-dry state
    1.284 32.119 90.217 3
    气干状态
    Air-dry state
    2.511 02.364 60.040 3
    纤维饱和状态
    Fiber saturation state
    1.906 92.364 60.098 2
    饱水状态
    Saturated state
    1.834 72.446 90.116 2
    注:绝干状态、气干状态以及纤维饱和点状态检验范围为0 ~ 32 nm,饱水状态检验范围为0 ~ 20 nm。Notes: the test range of oven-dry state, air-dry state and fiber saturation point state is 0 − 32 nm, and that of saturated state is 0 − 20 nm.
    下载: 导出CSV
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出版历程
  • 收稿日期:  2021-07-14
  • 修回日期:  2021-09-26
  • 网络出版日期:  2021-10-08

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