Department of Biomaterials, International Centre for Bamboo and Rattan, No. 8, Futong East Street, Chaoyang District, Beijing, People's Republic of China.
SFA and Beijing Co-built Key Laboratory of Bamboo and Rattan Science and Technology, State Forestry Administration, Beijing, People's Republic of China.
Sci Rep. 2021 Jun 16;11(1):12714. doi: 10.1038/s41598-021-92103-4.
Bamboo is an anisotropic, hierarchical, and hygroscopic material. Moisture transport in bamboo is one of the most fundamental properties affecting almost all other physical and mechanical properties of the material. This study investigated the water vapor sorption behaviors of bamboo at various structural levels: cell walls, cells (with pits) and bamboo blocks. The specimens with two sorption directions, longitudinal (L) and transverse (T), were measured by saturated salt solution method and dynamic vapor sorption. The parallel exponential kinetics model was used to analyze the sorption kinetics. The results showed that at the cell wall level, the sorption rate and equilibrium moisture content (EMC) of cell wall in the L specimens were larger than those in the T specimens. The differences were probably caused by the looser cell wall layers in the L specimens. At the cellular scale, pits in the cell wall resulted in an enhanced sorption rate and EMC of the T specimens compared with the L specimens where the pits in the parenchyma cells were only distributed in the lateral walls but not in end walls. At the macro scale, the sorption rate and moisture content of bamboo blocks were largely controlled by the vessel cells. As a hierarchically-structured plant, bamboo performs the biological function of moisture transport at all these scales. This work helps improve the understanding of water transport behavior in bamboo, which may lead to better bamboo drying and impregnation processes.
竹子是一种各向异性、多层次和吸湿的材料。水分在竹子中的传输是影响材料几乎所有其他物理和力学性能的最基本特性之一。本研究在不同的结构层次上研究了竹子的水蒸气吸附行为：细胞壁、细胞（有孔）和竹块。通过饱和盐溶液法和动态蒸汽吸附法测量了具有两个吸附方向（纵向（L）和横向（T））的试样。采用平行指数动力学模型分析了吸附动力学。结果表明，在细胞壁水平上，细胞壁 L 方向的吸附速率和平衡含水量（EMC）大于 T 方向的吸附速率和 EMC。差异可能是由于 L 方向的细胞壁层较松散。在细胞尺度上，细胞壁中的孔导致 T 方向的吸附速率和 EMC 增强，而在 L 方向中，只有在侧壁上分布有孔，而在端壁上没有孔。在宏观尺度上，竹块的吸附速率和含水量主要由导管细胞控制。作为一种具有层次结构的植物，竹子在所有这些尺度上都表现出水分传输的生物学功能。这项工作有助于提高对竹子中水分传输行为的理解，从而可能导致更好的竹子干燥和浸渍过程。
