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【目的】竹木材料孔隙结构特征是影响材料性能的重要因素。通过定量表征与直观观察相结合方式探索竹木材料内部孔隙结构特征。通过对比分析,建立竹木材料内部孔隙结构与组织构造的对应关系,分析竹木材料内部孔隙结构差异,研究孔隙结构对材料性能的影响。【方法】以毛竹和樟子松木材为试验材料,采用压汞法对材料的孔隙率、孔体积、孔径分布、比表面积等参数进行定量测试,分析材料的孔隙结构特征。采用扫描电镜对材料的组织结构(毛竹:导管、筛管、薄壁细胞和纹孔等部位。樟子松:管胞、射线薄壁细胞、纹孔等部位)进行观察,确定各组织结构所构成孔隙的孔径范围。【结果】孔隙率(毛竹47.58%、樟子松67.16%)及汞压入量(毛竹0.633 m L/g、樟子松1.596 m L/g)测试结果表明毛竹内部孔体积显著低于樟子松。总孔面积(毛竹82.04 m~2/g、樟子松18.16 m~2/g)及中孔孔径(毛竹33.8 nm、樟子松445.0 nm)对比结果表明毛竹中大部分孔隙集中在孔径较小区域(32.4 nm左右),而樟子松木材中孔隙孔径主要集中在226.7、7 082.3 nm左右,造成毛竹孔面积显著高于樟子松木材。结合扫描电镜观察结果可知,毛竹中孔径11.3~100μm范围内孔隙主要对应导管、基本组织中的薄壁细胞及纤维细胞。而835.0 nm左右孔隙对应基本组织及纤维细胞上纹孔。樟子松木材中孔径20μm左右孔隙对应樟子松木材管胞;而7 082.3 nm左右孔隙则对应具缘纹孔的纹孔口和射线薄壁细胞。此外,毛竹和樟子松木材中孔径小于1μm的孔隙结构(毛竹中32.4 nm左右,樟子松木材中226.7、749.9 nm左右)主要位于具缘纹孔塞缘及细胞壁上。【结论】采用压汞法和扫描电镜观察方法可以实现对毛竹及樟子松木材孔隙结构的表征分析,有助于分析竹木材料性能差异产生的原因。然而,在通过压汞测试材料孔隙结构参数时,受墨水瓶孔效应影响,部分孔径较大的孔隙被认为是小孔,影响测试结果的准确性。因此,后续研究应考虑竹木材料的孔隙形态,从而实现对竹木材料孔隙结构的全面准确表征。
【Objective】 The pore structure of bamboo is an important factor affecting the material properties. Through the combination of quantitative characterization and visual observation, the pore structure of bamboo material was explored. Through the comparative analysis, the corresponding relationship between the internal pore structure and the structure of the bamboo material is established, the difference of the internal pore structure is analyzed, and the influence of the pore structure on the material properties is analyzed. 【Method】 Bamboo and Pinus sylvestris var. Mongolica were used as materials to quantitatively test the porosity, pore volume, pore size distribution and specific surface area of the material by mercury intrusion porosimetry. The pore structure of the material was analyzed. Scanning electron microscopy (SEM) was used to observe the tissue structure (Phyllostachys pubescens: catheters, sieve tubes, parenchyma cells and pits and other parts of Pinus sylvestris: tracheid, ray parenchyma, pits and other parts) to determine the structure of the organization The pore size that makes up the pore. 【Result】 The results showed that the pore volume of bamboo was significantly lower than that of Pinus sylvestris (47.58% for Moso bamboo and 67.16% for Pinus sylvestris) and mercury intrusion (0.633 m L / g for Moso bamboo and 1.596 m L / g for Pinus sylvestris) loose. Comparison of the total pore area (82.04 m 2 / g, 18.16 m 2 / g Pinus sylvestris var. Mongolica) and the mesopore diameter (33.8 nm for Phyllostachys pubescens and 445.0 nm for Pinus sylvestris var. Mongolica) (About 32.4 nm), while the Pinus sylvestris wood pore pore size is mainly concentrated in the 226.7,782.3 nm or so, resulting in the area of the bamboo is significantly higher than the Pinus sylvestris wood. Combined with the results of scanning electron microscopy, we can see that the pores in the pores of 11.3 ~ 100μm in Phyllostachys pubescens mainly correspond to the catheters, the parenchyma cells and the fibroblasts in the basic tissues. While the 835.0 nm orifices correspond to the basic tissues and the pits on the fibroblasts. The Pinus sylvestris var. Mongolica wood has a pore size of about 20 μm in diameter corresponding to Pinus sylvestris wood tube traps; while the 7 082.3 nm orifices correspond to the stomatal aperture and the ray parenchyma cells with margined pits. In addition, the pore structure of Phyllostachys pubescens and Pinus sylvestris var. Mongolica with pore size less than 1 μm (about 32.4 nm in bamboo and 226.7,749.9 nm in Pinus sylvestris var. Mongolica) is mainly located at the margin and cell wall with margins. 【Conclusion】 The results showed that the pore structure of bamboo and Pinus sylvestris var. Mongolica can be characterized by mercury intrusion and scanning electron microscopy. It is helpful to analyze the reasons for the difference in the properties of bamboo wood. However, when mercury porosimetry is used to test the pore structure parameters of the material, pores with larger partial pores are considered as small pores, which will affect the accuracy of the test results. Therefore, the follow-up study should consider the pore morphology of bamboo material in order to achieve a comprehensive and accurate characterization of the pore structure of bamboo material.