Department of Sustainable Bioproducts, Mississippi State University, MS 39762, United States.
Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, China.
Int J Biol Macromol. 2024 Jun;269(Pt 2):131877. doi: 10.1016/j.ijbiomac.2024.131877. Epub 2024 Apr 26.
Wood is a hygroscopic material that responds to the moisture changes of the surrounding environment through swelling and shrinkage, making it dimensionally unstable. Here, we introduce a facile metal-ion-modification (MIM) approach to enhance the dimensional stability of wood. The MIM process involved swelling the wood samples with aqueous metal ion solutions and drying. The high valent metal cations, such as Fe, Al, and Zr, interacted with the hydrophilic groups (e.g., OH, COOH) present in the wood fibers, limiting their access to water and moisture, thereby enhancing the wood's hydrophobicity and dimensional stability. Evaluation of three wood species, southern yellow pine, poplar, and red oak, revealed water contact angles of 120-130° after MIM, indicative of enhanced surface hydrophobicity. Fe treatment decreased southern yellow pine's swelling ratio from 6 % to 4 %. Fe-treated wood exhibited tangential anti-swelling efficiencies ranging from 39.83 % to 57.14 % and radial anti-swelling efficiencies from 34.74 % to 48.33 %, varying across wood species. The enhancement of wood dimensional stability can be attributed to the formation of irreversible coordination bonds between metal cations and lignocellulosic microfibrils in the wood cell wall. These bonds prevent the microfibrils from slipping in response to moisture absorption and desorption.
木材是一种吸湿材料，会通过膨胀和收缩对周围环境的湿度变化做出反应，从而导致其尺寸不稳定。在这里，我们介绍了一种简便的金属离子改性（MIM）方法来提高木材的尺寸稳定性。MIM 过程涉及用含金属离子的水溶液使木材样品膨胀，然后干燥。高价金属阳离子（如 Fe、Al 和 Zr）与木材纤维中存在的亲水性基团（如 OH、COOH）相互作用，限制了它们对水和水分的接触，从而提高了木材的疏水性和尺寸稳定性。对南方黄松、杨木和红橡木三种木材的评估表明，MIM 后木材的水接触角为 120-130°，表明表面疏水性增强。Fe 处理将南方黄松的膨胀率从 6%降低到 4%。Fe 处理后的木材表现出的径向和切向抗膨胀效率分别为 39.83%-57.14%和 34.74%-48.33%，因木材种类而异。木材尺寸稳定性的提高可归因于金属阳离子与木材细胞壁中木质素纤维素微纤维之间形成不可逆的配位键。这些键防止微纤维在吸收和释放水分时滑动。
