The moisture-induced recovery of compressed wood is one of the major problems of wood densification technology. Achieving a cost-efficient surface densification process without the need for additional resins to eliminate the set-recovery may lead to an increase in value of low-density wood species. A previous study has shown that a pre-treatment with ionic liquids (ILs) can nearly eliminate the set-recovery. It was however observed that during the pre-treatment process the IL did not penetrate sufficiently deep into the wood to explain the achieved reduction in set-recovery. Based on these findings, the hypothesis was posed that further penetration of the IL into the wood occurs during the densification stage as a consequence of the applied heat and pressure. Thermo-gravimetric analysis (TGA) and gas-chromatography mass-selective-detection (GC-MSD) showed that the depth of penetration of the IL was greater after the densification process than before. Digital image correlation (DIC) showed that in regions with a high IL concentration, there was almost no set-recovery, and it gradually increased with a decrease in the IL concentration, as observed with TGA and GC-MSD analysis.

中文翻译：

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苏格兰松表面致密化过程中离子液体的原位渗透

水分引起的压缩木材的回收是木材致密化技术的主要问题之一。实现经济高效的表面致密化过程而不需要额外的树脂来消除凝固恢复可能会增加低密度木材的价值。之前的一项研究表明，使用离子液体 (IL) 进行预处理几乎可以消除凝固恢复。然而，观察到在预处理过程中，IL 没有深入到木材中，以解释所实现的凝固恢复减少。基于这些发现，提出了一个假设，即在致密化阶段，由于施加的热量和压力，IL 会进一步渗透到木材中。热重分析 (TGA) 和气相色谱质量选择检测 (GC-MSD) 表明，在致密化过程之后，IL 的渗透深度比之前更大。数字图像相关（DIC）显示，在高IL浓度的区域中，几乎没有凝固恢复，并且随着TGA和GC-MSD分析观察到，随着IL浓度的降低，它逐渐增加。