摘要
木材微区结构与木材宏观性质密切相关,杨木应拉木与对应木宏观性质存在较大差别,探究杨木应拉木和对应木微区结构和化学成分,可为了解杨木应力木的宏观性质提供理论根据。借助光学显微镜、荧光显微镜、显微拉曼成像光谱仪、透射电镜对杨木应拉木微区结构进行可视化研究,并借助X射线衍射技术和美国可再生能源实验室方法,分析杨木应拉木的微晶尺寸、结晶度以及化学成分。结果表明:杨木应拉木中应拉区和对应区纤维细胞微区结构差异显著。光学显微镜下显示应拉区木纤维中胶质层清晰可见,荧光显微镜和拉曼显微镜下显示胶质层的木质素浓度比对应区低。透射电镜下显示应拉区木纤维细胞壁结构由初生壁、次生壁和胶质层组成,未见次生壁外层,各层的平均厚度分别为0.61,1.22和2.53μm。对应区木纤维为典型的初生壁和次生壁结构,次生壁各层平均厚度分别为0.33,2.28和0.14μm。杨木应拉区纤维素含量(58.91%)比对应区(41.53%)高,木质素含量和半纤维素含量均比对应区的低,应拉区木质素和半纤维素含量分别为21.99%和12.01%,对应区分别为28.10%和17.08%。杨木应拉区结晶度(48.06%)比对应区(41.01%)高,应拉区晶区宽度为2.66 nm,长度为8.84 nm;对应区晶区宽度为2.65 nm,长度为9.87 nm。
Poplar is one of the commonly used fast-growing wood in China,which is easy to produce tension wood during tree s growth.Compared with the normal wood of poplar,the macroscopical properties of tension wood has very large differences.In the processes of processing and utilization,it is prone to produce a series of problems such as fluffing,difficulty in drying,air shrinkage,warping,cracking,etc.The utilization scope is also subject to a great limit.However,the macroscopic properties of wood are closely related to the microzone structure of wood.Therefore,in-depth study on the microzone structure and chemical composition of poplar stress wood can provide theoretical basis for understanding the macroscopic properties of the poplar stress wood,so as to reduce the loss caused by the defects of poplar stress wood and improve its utilization rate.In this study,the optical microscope,fluorescence microscope,micro-Raman imaging spectrometer and transmission electron microscope were used to visually examine the micro-structures of the tension wood and opposite wood.The crystallite size,degree of crystallinity and chemical components of the poplar tension wood and opposite wood were examined using XRD and NREL.The results showed that there were significant differences in the micro-structures of fiber cell walls between the tension wood and the opposite wood.The gelatinous layer(G)was well-defined in the tension wood and the lignin concentration of G-layer was lower than that of the opposite wood.The structure of the tension wood cell wall was composed of primary wall(P),secondary wall(S 1+S 2)and gelatinous layer(G).S 3 layer was not found and the average thicknesses of each layer were 0.61,1.22 and 2.53μm,respectively.The opposite wood was typical primary wall(P)and secondary wall(S 1+S 2+S 3).The average thicknesses of the secondary wall were 0.33,2.28 and 0.14μm,respectively.The content of cellulose in the poplar tension wood area(58.91%)was higher than that of the opposite wood(41.53%).The lignin content(21.99%)and hemicellulose content(12.01%)of the tension wood were lower than the lignin content(28.10%)and hemicellulose content(17.08%)in the opposite wood area.The degree of crystallinity of tension wood was higher than that of the opposite wood.The crystalline regions width and length of the poplar tension wood were 2.66 and 8.84 nm,respectively.The width and length of the opposite wood were 2.65 and 9.87 nm,respectively.
作者
朱玉慧
闻靓
张耀丽
王新洲
ZHU Yuhui;WEN Liang;ZHANG Yaoli;WANG Xinzhou(College of Materials Science and Engineering,Nanjing Forestry University,Nanjing 210037,China)
出处
《林业工程学报》
CSCD
北大核心
2020年第3期54-58,共5页
Journal of Forestry Engineering
基金
国家重点研发计划(2017YFD0600202)
国家自然科学基金(31670558)。
关键词
应拉木
杨木
细胞壁
微区结构
化学分布
tension wood
Populus deltoides CL.‘Nanyang’
cell wall
micro-structure
chemical distribution
