毛竹纤维细胞壁微纤丝取向与超微构造研究

发布时间：2017-12-26 23:14

  本文关键词：毛竹纤维细胞壁微纤丝取向与超微构造研究　出处：《中国林业科学研究院》2016年博士论文　论文类型：学位论文

  更多相关文章： 竹纤维细胞壁 超微构造 纤维素微纤丝 原子力显微镜 微纤丝角

【摘要】：竹材纤维细胞壁是植物体的力学承载单元,决定着植物体的物理、力学和化学性能,其独特的厚薄交替多壁层结构赋予了竹材纤维优良的物理力学性质。深入研究竹纤维细胞多壁层微纤丝取向与超微构造,不仅有助于深入理解竹子的解剖构造,而且对于竹材高附加值利用以及仿生材料设计等都具有重要的理论和现实意义。本文主要以毛竹(Phyllostachys edulis(Carrière)J.Houz.)第10节中部的纤维细胞为研究对象,利用偏振光显微镜(PLM)、场发射环境扫描电镜(FEG-SEM)、原子力显微镜(AFM)对竹纤维细胞壁形貌以及纤维细胞壁各壁层微纤丝取向进行了研究。重点利用原子力显微镜研究了毛竹纤维细胞各壁层微纤丝取向、细胞壁内部精细结构以及微纤丝超微构造。在了解纤维细胞结构的基础上,利用同步辐射广角X射线散射技术(SR-WAXS)从晶体角度对纤维素微纤丝的晶胞模型、结晶度、晶粒尺寸与晶型等晶体结构进行研究。然后利用X射线粉末衍射仪(XRD)、同步辐射广角X射线散射(SR-WAXS)技术、小角X射线散射(SR-SAXS)技术等多种方法研究竹材微纤丝角,通过多种计算方法研究竹材的微纤丝角,从多角度探索竹材纤维细胞壁的多壁层微纤丝取向与超微构造。得出以下的主要结论:(1)利用PLM、FEG-SEM、AFM对纤维细胞微纤丝取向方法比较得知:利用PLM可以初步判断次生壁微纤丝角,纤维细胞厚层的微纤丝角较小,近乎与细胞轴平行,而薄层的微纤丝角较大,与细胞轴近乎垂直。利用PLM更易观察壁层数量,具有2~3个厚层纤维细胞在纤维鞘中的占比为66%。利用FEG-SEM观察脱木素处理后的纵切片,可以清晰的观察到局部壁层的微纤丝角。利用AFM不仅观察到部分壁层的微纤丝角,还可测量初生壁、胞间层、薄层等厚度。综合以上3种设备的测试结果,AFM研究微纤丝取向是一种较优的技术手段。(2)利用AFM观察脱木素弦切片,纤维细胞次生壁的微纤丝角有90°、60°、30°、10°等分布。利用AFM对竹纤维细胞壁斜切面进行连续观察,通过三维重构的方式无法获得完整纤维细胞壁的结构,但可以对壁层内部和微纤丝的超微构造进行研究。纤维细胞中有与纹孔相通横向物质。细胞壁壁层内部结构是由一层层定向排列良好的微纤丝层(细胞壁亚层)组成,其厚度为20nm,亚层之间填充着直径约为18nm的木质素颗粒。微纤丝可以由单个或多个原纤丝组成,绝大多数微纤丝截面是由3~4个原纤丝组成,尺寸为15~20nm。基于多种手段的研究结果和前人研究的基础上,细化了具有2个生长周期层与细胞壁亚层结构的细胞壁模型:初生壁微纤丝呈网状排列,微纤丝与细胞主轴的夹角度数较大,初生壁厚度范围在50nm~80nm之间。初生壁向内是最外层的次生壁(O),微纤丝角为80°~90°,其厚度分布在100nm~1μm之间。一个生长周期层内,靠外侧的微纤丝角较大,约为80°,向内侧的微纤丝角从70°至30°快速递减,构成过渡层,过渡至微纤丝角较小的厚层,厚层的微纤丝角分布范围在5°~20°。过渡层厚度在整个纤维细胞中的厚度不同,在细胞中部的厚度较薄,在纺锤形纤维细胞两端厚度较大,过渡层厚度范围在100nm~400nm之间,在显微镜下呈现为薄层。细胞腔内的微纤丝取向的排列整齐度较差,微纤丝角在30°~60°之间。(3)毛竹纤维素晶胞为单斜晶系,模型若以b轴为纤维轴,晶胞参数为:a=8.35?,b=10.38?,c=8.02?,β=84.99°。毛竹在赤道方向和子午方向均探测到竹材具有结晶性,利用峰高法的计算结晶度结果比分峰拟合法的计算值高15%~20%。毛竹纤维素晶体的长为16.15nm、宽为2.69nm。毛竹中的纤维素是由单斜晶系的纤维素Ⅰβ占据绝对主导地位。(4)当竹材细胞沿主轴方向的旋转时,使用0.6T法计算竹材微纤丝角的结果无明显影响,这与0.6T法的计算理论相违背,因此,0.6T法计算毛竹平均微纤丝角存在一定局限性。通过XRD和SR-WAXS对毛竹试样(002)和(040)晶面衍射峰的比较,利用SR-WAXS测试得到的曲线光滑程度明显较好,使用(002)晶面计算平均微纤丝角的结果分别为9.19°和7.91°,通过XRD对试样(040)晶面衍射峰积分法计算得到的平均微纤丝角为11.02°,通过SR-WAXS的测试结果竹材微纤丝角为6.37°,若不扣除基底,利用(040)晶面计算得到毛竹微纤丝角为11.35°,以上结果均显示毛竹具有较小的微纤丝角。通过SR-SAXS研究结果表明毛竹的微纤丝主要以轴向分布为主,结合毛竹的解剖特征,纤维细胞的微纤丝角为0°~15°,薄壁细胞的微纤丝角约为60°。
[Abstract]:Bamboo fiber cell wall is the mechanical bearing unit of plant. It determines the physical, mechanical and chemical properties of plants. Its unique thickness and alternate multi walled structure endows bamboo fiber with excellent physical and mechanical properties. Further studies on the orientation and ultrastructure of bamboo fiber cell multi wall microfibrils not only help to understand the anatomical structure of bamboo deeply, but also have important theoretical and practical significance for the high value added utilization of bamboo and bionic material design. This paper mainly from bamboo (Phyllostachys edulis (Carri re) J.Houz.) tenth middle cells as the research object, using polarized light microscopy (PLM), field emission scanning electron microscope (FEG-SEM), atomic force microscopy (AFM) on the cell wall of bamboo fiber morphology and fiber cell wall layer of the wall of microfibril orientation to study. The microfibril orientation, the fine structure inside the cell wall and the ultrastructure of the microfibril were studied by atomic force microscopy. On the basis of understanding the structure of fibroblasts, synchrotron radiation, wide angle X ray scattering (SR-WAXS) technology was used to study the crystal cell structure, crystallinity, grain size and crystal structure of cellulose microfibrils from the point of view of crystal. Then using X - ray diffraction (XRD), wide-angle X-ray scattering of synchrotron radiation X (SR-WAXS), small angle X ray scattering (SR-SAXS) technique and other methods to study the bamboo microfibril angle, through a variety of calculation methods of microfibril angle of bamboo, explore the wall layers of cell wall of bamboo wood microfibril orientation with the micro structure from multiple perspectives. Draw the following conclusions: (1) compared with that by PLM, FEG-SEM, AFM on fibroblast microfibril orientation method: PLM could estimate the secondary wall of microfibril angle, microfibril angle of small fiber cell thick, almost parallel with the cell axis, and microfibril angle is large and thin, near the cell axis vertical. The number of wall layers was more easily observed with PLM, and the proportion of 2~3 thick layer fibroblasts in the fiber sheath was 66%. The longitudinal section of the delignification was observed by FEG-SEM, and the microfibril angle of the local wall could be clearly observed. AFM is used not only to observe the microfibril angle of the partial wall, but also to measure the thickness of the primary wall, intercellular layer and thin layer. According to the test results of the above 3 kinds of equipment, the AFM study of microfibril orientation is a better technical means. (2) using AFM to observe the delignification section, the microfibril angles of the secondary wall of the fibroblasts were 90, 60, 30 and 10 degrees. Using AFM to observe continuously the oblique section of bamboo fiber cell wall, we can not get the structure of the whole fiber cell wall by three-dimensional reconstruction, but we can study the ultrastructure of the inner wall and microfibril of the bamboo wall. In the fibroblast, there is a transverse material that is connected with the striate hole. The inner structure of cell wall layer is composed of a well arranged microfibril layer (cell wall sub layer). Its thickness is 20nm, and its sub layer is filled with lignin particles with diameter of 18NM. The microfibrils can be composed of single or multiple fibrils. Most of the microfibrils are made up of 3~4 fibrils with a size of 15~20nm. Based on the research results of previous studies and various methods on the refinement of the model with 2 layers of cell wall growth cycle and cell wall layer structure: the microfibrils in reticular arrangement, and spindle cell microfibril angle number of degree is large, the primary wall thickness in the range of 50nm~ 80nm. The primary wall is inward in the outer layer of the secondary wall (O), and the microfibril angle is 80 ~90 degrees, and its thickness is distributed between 100nm~1 and M. In a growth cycle, the lateral microfibril angle is larger than about 80 degrees, and the microfibril angle decreases rapidly from 70 to 30 degrees. It forms a transition layer, and transfers to a thicker microfibril angle. The thickness of microfibril angle ranges from 5 to ~20 degrees. The thickness of the transition layer is different in the whole fiber cell, the thickness in the middle part of the cell is thinner, the thickness at the ends of spindle fiber cells is larger, the thickness of the transition layer is between 100nm~400nm, and it appears as thin layer under microscope. The alignment of microfibril orientation in the cell cavity was poor, and the microfibril angle was between 30 degrees ~60 degrees. (3) the cell of bamboo cellulose is monoclinic, and the model is b axis, and the parameters of cell are a=8.35?, b=10.38?, c=8.02?, beta =84.99. Bamboo has crystallinity in the equatorial direction and meridional direction. The calculated value of the calculated crystallinity of the peak height method is 15%~20% higher than that of the peak fitting method. The cellulose crystal of Phyllostachys pubescens is 16.15nm in length and 2.69nm in width. The cellulose in Phyllostachys pubescens is dominated by the cellulose I beta of the monoclinic system. (4) when bamboo cells rotate along the main axis, the results of bamboo fiber microfibril angle calculated by 0.6T method have no obvious effect, which is contrary to the calculation theory of 0.6T method. Therefore, the 0.6T method has limitations in calculating the average microfibril angle of bamboo. Through XRD and SR-WAXS on bamboo samples (002) and (040) comparison of diffraction peaks, using SR-WAXS test smooth curve was significantly better, the use of (002) crystal surface to calculate the average microfibril angle results were 9.19 degrees and 7.91 degrees, the XRD of the sample (040) the average microfibril calculation get the diffraction peak integral angle is 11.02 degrees. Through the test results of SR-WAXS bamboo microfibril angle is 6.37 degrees, if not less substrate, using (040) crystal plane calculated bamboo microfibril angle is 11.35 degrees, the above results show that bamboo has smaller microfibril angle. The results of SR-SAXS showed that the microfibrils of bamboo were mainly axial distribution. Combined with the anatomical characteristics of Phyllostachys edulis, the microfibril angle of fibroblasts was 0 degree ~15 degrees, and the microfibril angle of parenchyma cells was about 60 degrees.
【学位授予单位】：中国林业科学研究院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S795.7
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本文编号：1339256