For wood, water diffusivity is an important factor that influences its mechanical and physical properties. In this experimental study, the water absorption and desorption were investigated in linear directions for woods of two Eucalyptus clones; Eucalyptus grandis and Eucalyptus camaldulensis. The diffusion model based on Fick’s second law was applied to assess both water absorption and desorption processes on cubic wood samples of (20 × 20 × 20) mm3. The diffusion coefficient, absorption coefficient, surface emission and diffusivity resistance were estimated. The study of sorption kinetics was carried out at ambient temperature about 25 °C and desorption kinetics at 30 °C for 12 h. The obtained results indicate that the sorption and desorption kinetics as well as the diffused quantities of water in the wood of these two clones were greater in the longitudinal direction than in the radial direction and that they were the lowest in the tangential direction. Wood samples of E. grandis exhibit higher average values of diffusion coefficient, absorption coefficient, and surface emission coefficient in both absorption and desorption processes in the linear directions than those of E. camaldulensis. However, they display lower average values of resistance diffusivity in all directions than those E. camaldulensis in both absorption and desorption processes.

中文翻译：

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无性系桉木中水分线性扩散的实验研究

对于木材，水的扩散性是影响其机械和物理性能的重要因素。本实验研究了两种桉树无性系木材在线性方向上的吸水和解吸；Eucalyptus grandis 和 Eucalyptus camaldulensis。应用基于菲克第二定律的扩散模型来评估 (20 × 20 × 20) mm3 立方木材样品的吸水和解吸过程。估计了扩散系数、吸收系数、表面发射和扩散阻力。吸附动力学的研究在环境温度约 25 °C 下进行，解吸动力学在 30 °C 下进行 12 小时。所得结果表明，这两个克隆在木材中的吸附和解吸动力学以及水的扩散量在纵向上大于径向，在切向方向上最低。E. grandis 木材样品在线性方向的吸收和解吸过程中的扩散系数、吸收系数和表面发射系数的平均值高于 E. camaldulensis。然而，在吸收和解吸过程中，它们在所有方向上的电阻扩散率平均值都低于那些 E. camaldulensis。在线性方向的吸收和解吸过程中，grandis 的扩散系数、吸收系数和表面发射系数的平均值高于 E. camaldulensis。然而，在吸收和解吸过程中，它们在所有方向上的电阻扩散率平均值都低于那些 E. camaldulensis。在线性方向的吸收和解吸过程中，grandis 的扩散系数、吸收系数和表面发射系数的平均值高于 E. camaldulensis。然而，在吸收和解吸过程中，它们在所有方向上的电阻扩散率平均值都低于那些 E. camaldulensis。