| 简介： |
|
刘瑞刚1，于 慧1，黄 勇1*，姜 勇1，董宝中2，吴中华2
(1中国科学院化学研究所高分子物理与化学国家重点实验室，北京 100080; 2中国科学院高能物
理研究所北京同步辐射实验室，北京 100039，E-mail: yhuang@cashq.icas.ac.cn)
通过化学方法从生物质中提取出纤维素，通过FTIR、WAXS、SEM、AFM和同步辐射小角X射线散射（SR-SAXS）对生物质中纤维素的形态结构进行了研究。结果表明，通过所采用的化学方法，可以完全去除生物质中的半纤维素和木质素，并且只有纤维素Ib结晶晶型存在（Fig.1）[1]。生物质中的纤维素纤维素是结晶不完善的纤维素I结晶结构，结晶度约为40%
（Fig. 2）。偏振光FTIR结果表明，生物质中表皮组织中的纤维素分子沿生长方向具有较好的平均取向结构，而内部的薄壁细胞组织中的纤维素的分子链几乎没有取向。
SEM结果发现，在生物质的表皮细胞中有两种纤维状结构，一种是由微纤组成的棒状结构，一种是边缘由锯齿状结构（Fig. 2a），而在微管束中纤维素呈环状或螺旋状结构，周围包复一层很薄的纤维素薄膜（Fig.2b和c）。说明纤维素是生物质中的骨架节构。
纤维素在省物质中更细微的形态结构见Fig. 3。表皮中的纤维素由沿着纤维方向的有一定取向度的微纤组成（Fig. 3a），而在微管中的环状结构中，纤维素微纤基本上是垂直于环状结构的切线方向排列（Fig. 3b），而在内部的薄壁细胞组织中，纤维素微纤呈无规排列的类似于无纺布的结构。SR-SAXS散射图像表明纤维素的分子链在生物质中沿其生长方向有明显的取向结构（Fig. 4）。
参考文献：
[1] J. Sugiyama, J. Persson, H. Chanzy, Macromolecules, 1991, 24, 2461-2466.
[2] R. G. Liu, H. Yu, Y. Huang, Cellulose, 2003, accepted.
Morphology and Structure of Cellulose in Biomass
Ruigang Liu,1 Hui Yu,1 Yong Huang,1 Yong Jiang,1 Baozhong Dong,2 Zhonghua Wu2
1. State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, The Chinese Academy of Sciences, Beijing 100080, China, E-mail: yhuang@cashq.icas.ac.cn
2. Beijing Synchrotron Radiation Faculty, Institute of High Energy Physics, The Chinese Academy of Sciences, Beijing 100039, China
In this work, cellulose in biomass was extracted by chemical methods, and the morphology and structure of cellulose in wheat straw had been studied by FTIR, WAXS, SEM, AFM and synchrotron radiation small angle X-ray scattering (SR-SAXS). It was indicated that hemicelluloses and lignin were extracted almost completely. There is only cellulose Ib crystalline allomorph exits in the biomass. Cellulose in the epidermis of biomass has a higher orientation order in the growing direction whereas has almost no prefer orientation in the parenchyma part of the biomass. There are two kinds of morphology of cellulose in the epidermis of biomass, fibrillar structure with macrofibrils and the other with serration morphology at the edge. The framework in vascular has two morphologies, annular rings and spiral structure. The microfibril in the epidermis arranged prefer along the axis of the macrofibrils and arranged perpendicular to the tangential direction of annular rings. SR-SAXS results also show that cellulose chains orientated along the growing direction of the biomass. |
|
