The important anatomical changes in tension wood, e.g., the high fiber ratio and rich mesopores, did not significantly increase the air and nitrogen flow; thus the gas permeability in the longitudinal direction of poplar ( Populus deltoides CL.’55/65′) tension wood is actually affected by the cell tissue macroporous porosity. Gas permeability is one of the most important physical properties of wood and is closely related to its internal microstructure, particularly porosity. Tension wood is widespread in woody plants and displays significant structural differences compared with opposite wood. The study was designed to clarify the relationship between pore structure and gas permeability in poplar tension wood. The gas permeability was measured using a self-made device. The meso- and macroporosity characteristics were measured by nitrogen adsorption–desorption and mercury intrusion porosimetry. The flow was simulated using ANSYS Fluent software to illustrate the role of pore structure on permeability. The morphological features of vessels have an effect on wood permeability. Compared with tension wood, opposite wood, which has higher vessel ratio, larger cell lumen diameter, and more rich pits, shows stronger gas permeability. Increasing the airflow path will actually reduce the gas permeability. The simulation results are consistent with the experimental results. In hardwoods, the gas permeability in the longitudinal direction is mainly dictated by the vessels. The high fiber ratio and rich mesopore in tension wood do not significantly increase gas flow, suggesting the permeability of wood was actually determined by the cell tissue with macroporous porosity. Vessel tissue ratio, length and diameter, and intervessel pit size were found responsible for influencing the permeability in the longitudinal direction.

中文翻译：

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杨树（Populus deltoides CL.'55/65'）张拉材孔隙结构与透气性的关系

张力木的重要解剖学变化，例如高纤维比和丰富的介孔，并没有显着增加空气和氮气流量；因此杨树（Populus deltoides CL.'55/65'）张力木材纵向的透气性实际上受细胞组织大孔孔隙度的影响。透气性是木材最重要的物理特性之一，与其内部微观结构，尤其是孔隙率密切相关。抗张木广泛存在于木本植物中，与对生木材相比显示出显着的结构差异。该研究旨在阐明杨木张力木材的孔隙结构与透气性之间的关系。使用自制装置测量气体渗透率。通过氮吸附-解吸和压汞孔隙率测定法测量中孔和大孔特征。使用 ANSYS Fluent 软件对流动进行了模拟，以说明孔隙结构对渗透率的作用。血管的形态特征对木材的渗透性有影响。与张力木相比，对生木具有更高的血管比、更大的细胞管腔直径和更丰富的凹坑，表现出更强的透气性。增加气流路径实际上会降低气体渗透性。模拟结果与实验结果一致。在硬木中，纵向的透气性主要由血管决定。张力木中的高纤维比和丰富的介孔不会显着增加气体流量，表明木材的渗透性实际上是由具有大孔隙率的细胞组织决定的。发现血管组织比率、长度和直径以及血管间凹坑大小是影响纵向渗透性的原因。