This study aims at identifying the mechanisms of oil and water imbibition in heartwood and sapwood of Douglas-fir through a combination of original experiments with magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) relaxation measurements for oil and free water, and deformation measurements for bound water. Experiments by weighing are performed to verify whether the imbibition process is also consistent with Washburn law. All the results are discussed taking into account the structure of wood (tubular tracheids closed at their tips, but possibly connected to each other via open pits on the side faces) and the preparation of samples. The observation of relatively fast oil flow imbibition confirms that sapwood exhibits a connected hydraulic network through which a liquid can a priori flow and climb along the structure. However, the spontaneous water imbibition is strongly damped by its very poor wetting when in contact with cell-walls only partially saturated with bound water, so that the diffusion of bound water control the uptake dynamics. However, due to preferentially closed pits, the heartwood does not exhibit a continuous hydraulic network and water essentially penetrates into wood by diffusion through the cell walls.

中文翻译：

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从1H核磁共振方法推断道格拉斯冷杉液体吸收的机理

这项研究旨在通过将原始实验与磁共振成像（MRI）和核磁共振（NMR）弛豫测量相结合来确定花旗松心材和边材中油和水的吸水机理，以研究油和自由水的变形情况。束缚水的测量。通过称重进行实验，以验证吸水过程是否也符合沃什伯恩定律。讨论所有结果时都考虑到了木材的结构（管状的管胞在其顶端闭合，但可能通过侧面的凹坑相互连接）和样品的制备。观察到相对较快的吸油量，证实边材具有连通的液压网络，液体可以通过该液压网络先验地流动并沿着结构爬升。然而，当与仅部分结合水饱和的细胞壁接触时，自发水的吸湿性很差，从而极大地抑制了自发水的吸收，因此结合水的扩散控制了吸收动力学。然而，由于优先封闭的凹坑，心材没有表现出连续的水力网络，并且水基本上通过扩散穿过孔壁而渗入木材中。