弱酸改性对高温热处理杉木结构及性能的影响  

Effect of weak acid modification on the structure and properties of heat-treated Chinese fir

作　　者：高义钦 李元元 任瑞清 陈瑶[1] 高建民[1] GAO Yiqin;LI Yuanyuan;REN Ruiqing;CHEN Yao;GAO Jianmin(College of Materials Science and Technology,Beijing Forestry University,Beijing 100083,China)

机构地区：[1]北京林业大学材料科学与技术学院,北京100083

出　　处：《林业工程学报》2021年第4期49-55,共7页Journal of Forestry Engineering

基　　金：国家自然科学基金(31400498)。

摘　　要：为改善高温热处理木材的力学性能,采用亚硫酸钠/亚硫酸浸渍改性杉木,对木质素结构进行磺化修饰,以促进木质素在高温热处理过程中的迁移与重新分布。在高湿高压的环境下对改性杉木进行高温热处理,通过场发射扫描电子显微镜分析热处理前后杉木细胞壁表面微观构造,通过共聚焦激光扫描显微镜确定木质素在细胞壁中的半定量分布,测量了不同热处理条件下杉木的热稳定性、表面润湿性和抗弯性能。研究表明:热处理会破坏杉木细胞壁微观构造,细胞壁表面会出现球状或鳞片状熔融体,而经过亚硫酸氢根磺化改性后进行热处理的杉木细胞壁破坏程度减少,且细胞壁表面为分布更均匀的球状熔融体;亚硫酸氢根磺化处理以及高湿度使木质素玻璃化温度与熔点降低,亲水性增强,在热处理过程中木质素从浓度较高的细胞角和复合胞间层向细胞壁内侧迁移,并在细胞壁各壁层均匀分布,增加了微纤丝间的黏结强度;改性后的杉木经热处理后,静曲强度及弹性模量均高于未改性处理材。Thermally modified wood presents several disadvantages, such as poor mechanical properties, which limit its end-use possibilities. Modification under saturated steam was reported to result in higher performance when compared with most traditional thermal modification methods. To address the aforementioned drawbacks, Chinese fir(Cunninghamia lanceolata) samples were heated at 180 ℃ for 2 or 4 h with saturated steam as a heat-conducting media. Besides, this study used sodium sulfite/sulfurous acid to impregnate the modified Chinese fir samples and sulfonate the lignin structure to promote the migration and relocation of lignin during the heat treatment. Solution of sulfurous acid and sodium sulfite were prepared to modify lignin for the pretreatment to lower the glass transition temperature and the melt temperature of lignin, so that lignin can be partly fluidized and relocated. The modified Chinese fir samples were heat-treated under a high humidity and high pressure environment, and the surface microstructure of the wood cell wall before and after the heat treatment was analyzed by the field emission scanning electron microscope(FE-SEM), and the semi-quantitative distribution of lignin in the cell wall was determined by the confocal laser scanning microscope(CLSM). The morphological observation confirmed that the lignin droplets were formed in the ray cell walls. The thermal stability, hydrophilicity and bending resistance of Chinese fir samples under different heat treatment conditions were measured. The results showed that the heat treatment could destroy the microstructure of the cell wall of Chinese fir, with spherical or scaly melt appearing on the surface of the cell wall. It was provided the evidence supporting the idea that, when temperatures of thermal treatments exceeded the range for lignin phase transition, lignin could migrate within and out of the cell wall, and can redeposit on the surface of wood cell walls. The cell wall of Chinese fir after being modified by the bisulfite sulfonation would be

关 键 词：杉木 木材改性 高温热处理 抗弯性能 细胞壁微观结构 

分 类 号：S781.7[农业科学—木材科学与技术]