XPS和FTIR分析仿生呼吸法对硅酸盐改性杉木浸渍效果的影响

杉木进行硅酸盐浸渍改性处理后，木材内部的改性剂相关元素含量与分布是衡量浸渍效果的重要指标，对改性杉木的各项物理力学性能有着至关重要的作用。以硅酸盐为浸渍改性剂，采用仿生呼吸法对杉木进行浸渍改性。研究了仿生呼吸法对硅酸盐改性杉木的密度、抗弯强度、抗压强度、三切面硬度和24 h吸水率影响，利用XPS和FTIR分析了杉木素材与改性材的化学成份与化学结构，并对硅酸盐改性剂在改性杉木中的分布深度与分布规律进行了探讨。结果表明：经过硅酸盐浸渍改性后，改性杉木平均密度大于0.721 g·cm-3，抗弯强度和抗压强度分别增大了170.19%和286.64%。改性杉木横切面、径切面和弦切面的硬度均有不同程度的提高。硅酸盐改性使杉木的24 h吸水率从91.17%±2.51%降至39.23%±1.62%，表明杉木的尺寸稳定性大幅度提高。相比于杉木素材，改性杉木木材的XPS全谱扫描中出现了Na元素和Si元素的吸收峰，窄扫谱图中出现了Si-O-C和Na-O化学结构。同时，改性杉木木材的FTIR谱图中出现了Si-O-Si的吸收峰，并且游离羟基含量减少，缔合羟基增多。XPS和FTIR分析都表明硅酸盐浸注到了杉木木材的孔隙中，且硅酸钠与杉木木材中羟基形成了化学键结合和氢键结合。这也是改性杉木的力学性能和耐水性能提高的重要原因。另外，通过XPS测试发现改性杉木木材沿横向从表面到30 mm处都出现了C，O，Na和Si元素，并且沿横向从表面到30 mm处，Si-O-C结合结构的吸收峰强度基本相同，说明从表面到中间部位，硅酸钠与杉木木材中的羟基都较均匀地形成了化学键。对各元素进行定量分析发现，改性杉木木材中C，O，Na和Si元素的相对含量从表面到中间部位（30 mm）差异较小，进一步表明改性剂能较好浸入杉木木材中间，并且均匀性较好。研究结果将为杉木浸渍改性效果提供数据支撑，并为优化改性工艺与方法、进一步提高改性杉木的物理力学性能提供依据。

Effect of Biomimetic Respiration Method on the Impregnation Effect of Silicate Modified Chinese Fir by XPS and FTIR Analysis

After silicate impregnation,the content and distribution of elements in the modifier is an important index to evaluate the impregnation effect,which plays an important role in the physical and mechanical properties of the modified Chinese fir.The effects of the biomimetic respiration method on the density,bending strength,compressive strength,three section hardness and24 hwater absorption of silicate modified Chinese fir were studied.The chemical composition and structure of unmodified and modified Chinese fir were analyzed by XPS and FTIR,and the distribution depth and law of silicate modifier in the modified Chinese fir were discussed.The results showed that the average density of the modified Chinese fir was more than 0.721 g·cm^-3,the bending strength and compressive strength increased by 170.19%and 286.64%,respectively.The hardness of the transverse section,radial section and tangential section of the modified Chinese fir increased in different degrees.The 24 hwater absorption of Chinese fir decreased from 91.17%±2.51%to 39.23%±1.62%after silicate modification,which indicated that the dimensional stability of Chinese fir was greatly improved.Compared with the unmodified Chinese fir,the absorption peaks of Na and Si elements appear in the XPS full-spectrum scanning of the modified Chinese fir wood,and the chemical structures of Si—O—C and Na-O appear in the narrow spectrum scanning.At the same time,the absorption peak of Si—O—Si appeared in the FTIR spectrum of the modified Chinese fir wood,the content of free hydroxyl decreased,and the associated hydroxyl increased.XPS and FTIR analysis showed that silicates were impregnated into the pores of Chinese fir wood,and sodium silicate formed a chemical bond and hydrogen bond with hydroxyl in Chinese fir wood.This was also an important reason for the improvement of mechanical properties and water resistance of modified Chinese fir.In addition,it was found by XPS that C,O,Na and Si elements appeared along the transverse direction from the surface to 30 mm.The absorption peak intensity of Si—O—C bonding structure was basically the same from the surface to 30 mm,which indicated that the chemical bond between sodium silicate and hydroxyl groups in Chinese fir wood was formed more evenly from the surface to the middle part.It was found that the relative contents of C,O,Na and Si element in the modified Chinese fir wood were slightly different from the surface to the middle part(30 mm).The results showed that the modifier was in the middle of Chinese fir wood,and the uniformity was good.The research results will provide data support for the impregnation modification effect of Chinese fir,and provide the basis for optimizing the modification process and method,and further improving the physical and mechanical properties of modified Chinese fir.