毛竹孔隙结构及其液体渗透规律解析

As a kind of natural porous biomaterial, the pore structure of Moso bamboo affects its liquid permeability dramatically. Therefore, the characterization of the pore structure systematically is extremely important for uncovering the liquid permeation mechanism 0f moso bamboo. The present study plans to take scanning electron microscopy and micro-CT to obtain 2D and 3D images of moso bamboo’s pore structure, through which the qualitative characterization of its pore structure can be realized. The pore structural parameters such as the porosity and pore size distribution can be detected by mercury intrusion porosimetry and N2 adsorption method, while the pore structure features can be characterized based on fractal theory to realize the quantitative characterization of its pore structure. Based on aboved results, the pore structure model of moso bamboo can be established through image reconstruction technology. With this model, the liquid permeate routes in moso bamboo can be uncovered, and the theoretical illustration of liquid permeation mechanism can be realized. Besides, fluorescence microscopy and image processing method will be adopted to observe the status of liquid permeation in moso bamboo, which in turn verify the theoretical illustration of liquid permeation mechanism. The expected results of the present study can be a good supplement for the basic theoretical knowledge of bamboo utilization, and it could offer the solid theoretical foundation for developing of high performance bamboo-based materials and realizing the high value-added utilization of bamboo.

毛竹作为一种天然生物多孔材料，孔隙结构是影响其液体渗透性的重要因素，系统表征毛竹孔隙结构对于解析毛竹液体渗透规律具有重要意义。本项目以毛竹为研究对象，通过扫描电镜、显微CT观测，获得毛竹孔隙结构的二维及三维图像，实现对毛竹孔隙结构的定性表征。利用压汞法及氮吸附法测试毛竹孔隙率、孔径大小及孔径分布等结构参数；应用分形理论研究毛竹孔隙的孔形状特征，实现对毛竹孔隙结构的定量表征。在此基础上，通过图像重构技术构建毛竹孔隙结构模型，解析液体在毛竹内部的渗透路径，对毛竹液体渗透规律进行理论分析。结合荧光显微技术与图像处理技术，观测液体在毛竹内部渗透路径中的渗透状态，验证毛竹液体渗透规律的理论分析结果。本研究预期成果将丰富竹材研究的基础理论知识，同时为高性能的竹质材料的开发和竹材高附加值加工利用提供重要的理论依据。

液体渗透性是影响竹材功能化处理（如防霉、阻燃、染色等）、竹材胶合等加工处理效果的重要性能指标。毛竹作为一种天然生物多孔材料，孔隙结构如孔隙率、孔径大小等孔结构因素与竹材液体渗透性密切相关。对竹材液体渗透性的研究已经成为热点科学问题之一。对竹材液体渗透性的分析大多停留在显微结构分析层面。以毛竹孔隙结构表征为核心，建立毛竹显微构造、孔隙结构特征、毛竹液体渗透性三者之间的联系，揭示毛竹液体渗透规律，将为毛竹加工利用过程中的性能分析提供基础理论支撑。.本项目以毛竹为研究对象，采用扫描电镜观测方式，获得毛竹显微构造特征的二维图像；利用显微CT观测方式，获得毛竹导管、薄壁细胞及纤维细胞对应孔隙的三维结构模型，实现对毛竹孔隙结构的定性表征。利用压汞法测试毛竹内部孔隙的孔隙率、孔体积、比表面积等定量表征参数，通过真密度仪测试毛竹不同部位孔隙的开孔率，并结合孔隙三维结构模型，分析毛竹孔隙连通状态。从孔隙结构特征角度分析了毛竹不同方向上液体渗透特征，解析了毛竹纵向及横向液体渗透差异产生机理。通过示踪分析，获取毛竹内部液体渗透状态图像，验证了毛竹液体渗透规律理论分析结果。主要研究结论如下：毛竹整体孔隙率在47.58%左右。其中近竹青层孔隙率25.53%，竹肉层孔隙率57.77%，近竹黄层孔隙率为53.12%。导管对应孔隙尺度最大，孔径在90μm左右，且孔隙连通性最好；薄壁细胞对应孔隙孔径在30μm左右，连通孔隙比例约47.9%。竹纤维细胞对应孔隙孔径在10μm左右，连通孔隙比例约27.45%。纹孔对应孔隙孔径835.0nm。细胞壁中有大量孔径为32.4nm左右孔隙。理论及示踪分析结果表明，毛竹内部液体渗透过程中，纵向渗透速度大于横向渗透速度。其中，导管及薄壁细胞对应的孔隙尺寸大，连通性好，液体渗透效率高，而竹纤维部位孔隙尺寸小，连通性差，导致液体渗透效率低。