轻木细胞壁超微结构与力学性能关系研究

目的]研究轻木化学组成、纤维细胞壁分层结构和纤维素聚集态结构,探究其对力学性能的影响,为厘清轻木细胞壁超微结构与力学性能之间关系,提高其利用附加值奠定理论基础.方法]将轻木与我国常见阔叶木树种杨木进行对比研究,采用水解法分析两者的化学组成;用透射电子显微镜、共聚焦拉曼显微镜等表征纤维细胞壁分层结构、微区化学和纤维素...

Relationship between cell wall ultrastructure and mechanical properties of balsa wood

Objective]This study aims to investigate the chemical composition,cell wall ultrastructure and supramolecular structure of cellulose in balsa wood fibers,as well as reveal their influence on mechanical properties of balsa wood and demonstrate the relationship between ultrastructure and mechanical properties,to provide a theoretical basis for the high value applications of balsa wood.Method]Balsa wood and poplar wood were comparatively studied.Their chemical composition was analyzed by acid hydrolysis,and the cell wall structure was observed by transmission electron microscopy.Meanwhile,confocal Raman microscope was used to characterize the cell wall topochemistry and the supramolecular structure of cellulose.Result]The acetyl contents in balsa wood and poplar wood were 9.52%and 5.61%,respectively.The thickness of S3 layer of balsa wood fiber cell wall accounted for 5.49%of the total thickness of cell wall,which was higher than that of poplar wood(3.86%).The maximum microfibril angle in S2 layer of balsa wood fiber was 30°,smaller than that of poplar wood(40°).The orientation of cellulose microfibers in the cell lamella and S2 layer of balsa wood was more regular than that in the corresponding layers of poplar wood.Conclusion]The degree of xylan acetylation,cell wall ultrastructure and cellulose supramolecular structure of balsa wood were significantly different from that of poplar wood:the balsa wood exhibited the higher degree of xylan acetylation,the higher proportion of S3 layer in cell wall,the smaller microfibrils angle in S2 layer,and more orderly orientation of cellulose microfibrils in both cell lamella and S2 layer.This study not only explains the main reasons for the excellent mechanical properties of balsa wood with low density,but also provides significant theoretical reference for the cell wall topochemistry,the relationship between ultrastructure and mechanical properties and high value utilization of balsa wood.