硅镁凝胶对杉木的强化及固着机制研究

硅镁凝胶浸渍改性杉木在物理力学性能方面提升较佳，探究硅镁凝胶在杉木中的固着性能和机制，对后续研究与创新具有一定意义。以硅镁凝胶为改性药剂，人工林杉木为基材，浸渍干燥后制得改性杉木。通过FTIR和XPS分析杉木素材和改性杉木的化学成分和结合方式，并对硅镁凝胶在木材中的分布以及改性杉木的渗透性进行探讨。实验结果表明：硅镁凝胶浸渍改性杉木的物理力学性能得到明显改善，密度均达到0.5 g·cm-3以上，抗压强度和抗弯强度相比杉木素材分别提升了99.73%和58.48%，端面硬度从3 659 N提升到5 843 N，基本已达到中等木材的性能指标。EDS结果证明药剂在杉木细胞腔中填充状况良好，Si，O，Na和Mg等主要元素与浸渍药剂硅镁凝胶相符且分布均匀。对浸洗前后的改性杉木试样和素材分别进行分层XPS测试，改性材的O/C增大，各元素在不同深度的含量十分接近，硅镁凝胶在杉木中分布均匀，具有良好的渗透性；浸洗后Si元素含量稳定，而钠元素有所降低，可能是部分钠盐的溶解流失造成，且不同深度的元素含量变化趋于一致，改性杉木的抗流失性较好。相比于硅酸钠浸渍改性杉木，硅镁凝胶改性杉木在96 h流失率降低到10.8%，抗流失效果较好。FTIR测试结果表明硅酸钠溶液对杉木的木质素和半纤维素有破坏和脱出作用，对杉木的通透性有所改善，且更容易与药剂形成化学键结合。C，O和Si元素的XPS谱图结果表明，改性后C(1s)向低结合能偏移，性质更加稳定，O—H结合大量减少，Si—O结合增多，硅镁凝胶能够在杉木中形成稳定的Si—O—C化学结构，药剂能够在细胞壁上实现高效固着。研究结果为改性材的药剂流失性检测和固着性研究提供新的思路，为硅镁凝胶浸渍改性杉木后续研究提供一定的理论支持。

Study on Strengthening and Fixation Mechanism of Chinese Fir Modified by Silica-Magnesium Gel

The silica-magnesium gel impregnated modified Chinese fir has improved physical and mechanical properties. Exploring the fixing performance and mechanism of silica-magnesium gel in Chinese fir has significance for subsequent research and innovation. It is uses silica-magnesium gel as the modifying agent and fast-growing Chinese fir as the base material.Modified Chinese fir was prepared after dipping and drying. FTIR and XPS were used to analyze the chemical composition and combination of naturalChinese fir and modified Chinesefir and discussed the distribution of silica-magnesium gel in wood and the permeability of modified Chinese fir. The experimental results showed that the physical and mechanical properties of the modified Chinese fir impregnated with silica-magnesium gel hadbeen significantly improved, and the density was above 0.5 g·cm-3, the compressive strength and bending strength were increased by 99.73% and 58.48% compared with the natural Chinese fir.The end surface hardness was increased from 3 659 to 5 843 N, and it reached the performance index of medium wood. The results of EDS proved that the medicament was well filled in the cell cavity of the fir, and the main elements such as Si, O, Na, Mg and the impregnating medicament silica-magnesium gel were consistent and evenly distributed. Layered XPS tests were performed on the Chinese fir before and after impregnation. The O/C of the modified Chinese fir increased, and the content of each element at different depths was very close. The silica-magnesium gel was evenly distributed in the Chinese firand had good permeability.After leaching, the Si element content changed little, while the sodium element decreased, which may be caused by the dissolution and loss of some sodium salts, and the element content changes at different depths tend to be consistent. The resistance of the modified Chinese fir compared with sodium silicate, the loss rate of silica-magnesium gel was reduced to 10.8% in 96 h, and the effect was good. The FTIR test results of modified Chinese fir, natural Chinese fir, sodium silicate solution and leachate showed that the sodium silicate solution had the effect of destroying and leaching out the lignin and hemicellulose of Chinese fir, improving the permeability of Chinese fir and making it easier to interact with the medicament forms a chemical bond. The XPS spectrogram analysis of C, O, and Si elements showed that C(1s) shifted to low binding energy after modification, and the properties were more stable. The O—H binding was greatly reduced, and the Si—O binding increased. The silica-magnesium gel can form a stable in Chinese fir with a Si—O—C chemical structure, and the agent can achieve high-efficiency fixation on the cell wall. The research results provide new ideas for the loss detection and fixation research of modified wood and provide certain theoretical support for the follow-up study of modified Chinese fir impregnated with silica-magnesium gel.