不同预处理方法对木材细胞壁孔隙结构影响  

Effects of different pretreatment methods on the pore structure of wood cell wall

作　　者：王瑜瑶 马尔妮 Wang Yuyao;Ma Erni(Beijing Key Laboratory of Wood Science and Engineering,School 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,木材科学与工程北京市重点实验室,北京100083

出　　处：《北京林业大学学报》2023年第11期140-151,共12页Journal of Beijing Forestry University

基　　金：国家重点研发计划课题(2023YFD2200501);国家自然科学基金项目(31971583)。

摘　　要：【目的】探究水分所引发的木材细胞壁孔隙结构变化,并与微波处理、脱木质素处理等预处理方法进行比较,为木材改性提供科学依据。【方法】将20 mm(径向)×20 mm(弦向)×5 mm(轴向)的杨木和杉木试材分别通过泡水1 h和1个月的方法进行水分处理,在500 W条件下微波处理18 min,在酸性条件下使用亚氯酸钠脱除试材中部分木质素。通过扫描电子显微镜和氮气吸附测试表征处理材的细胞壁微观形貌与孔隙结构,比较不同处理方法对细胞壁厚度、比表面积、孔径分布及孔体积等的影响。【结果】水分处理后,杨木和杉木的细胞壁增厚,水分处理1 h试材的比表面积分别从1.535和1.154 m^(2)/g增加到2.488和2.336 m^(2)/g,水分处理1个月的试材比表面积进一步增加到2.822和2.940 m^(2)/g。水分处理杨木试材在微、介孔范围内形成新的孔隙(造孔),且存在孔径增大(扩孔)现象。对于水分处理杉木试材,处理时间较短时其微孔范围内孔体积变化主要表现为扩孔效应,随着时间增加同时具有造孔和扩孔现象。在介孔范围中由于水溶性抽提物的脱除产生较大孔隙,并导致孔径的重新分布。微波处理杨木和杉木试材的细胞壁厚度和比表面积变化同与水分处理类似,处理后杨木试材中产生部分微孔,且杨木介孔及杉木孔径分布都表现为扩孔。脱木质素处理杨木和杉木的细胞壁厚度分别减少了1.79%和0.53%,但比表面积均增加,杉木试材中的微孔增加,其他孔径分布变化均因扩孔所致。【结论】水分处理能够改变木材细胞壁孔隙结构,杨木和杉木泡水1 h和1个月的作用效果与质量损失率分别为1.29%和3.33%的微波处理,以及脱除率分别为10.94%和8.06%的脱木质素处理相当,并且具有独特的孔径分布变化规律。3种处理方法由于作用机理不同,增大孔体积的方式在不同树种的不同孔径范围内不尽相同。本研究为选择科[Objective]This paper explores the changes in pore structure of wood cell walls induced by water and compares this method with the pretreatment methods such as microwave treatment and delignification,in order to provide a scientific basis for wood modification.[Method]Poplar(Populus euramericana)and Chinese fir(Cunninghamia lanceolata)specimens of 20 mm(radial)×20 mm(tangential)×5 mm(longitudinal)were treated with water soaking for 1 h and 1 month,respectively,microwave treatment at 500 W for 18 min,as well as sodium chlorite under acidic conditions.The microscopic morphology and pore structure were characterized by scanning electron microscopy and nitrogen sorption test,and the effects of different treatment methods on cell wall thickness,specific surface area,pore size distribution and pore volume were compared.[Result]The cell walls of poplar and fir thickened after water treatment,and the specific surface area of the water-treated wood for 1 h increased from 1.535 and 1.154 m^(2)/g to 2.488 and 2.336 m^(2)/g,and that of water-treated wood for 1 month further increased to 2.822 and 2.940 m^(2)/g,respectively.For water-treated poplar,new pores were formed in the micropore and mesopore range(pore formation),and there was an increase in pore size(pore enlargement).For water-treated Chinese fir,the change in pore volume in the micropore range mainly reflected a pore enlargement effect,and there were both pore formation and enlargement phenomena with the increase of treating time.Larger pores were generated in the mesopore range due to the removal of water-soluble extractives,which led to a redistribution of pore size.The changes in cell wall thickness and specific surface area of microwave-treated poplar and Chinese fir were similar with those of water treatment,and some micropores were produced in poplar after microwave treatment,and the pore size distribution of mesopores in poplar and both pores in Chinese fir showed enlargement.The cell wall thickness of poplar and fir treated with delignification decreased

关 键 词：木材水分 细胞壁孔隙 微波处理 脱木质素处理 

分 类 号：S781.33[农业科学—木材科学与技术]