木质纤维超微结构的生物与化学修复以及其对纤维形变性能的响应机制研究

The deformation properties of wood fibers affect their bonding ability and all kinds of optical and physical properties directly. There is significant negative relationship between bonding characteristics and bulk of high-yield pulp (HYP) fibers dissociated by physical and chemical means from biomass, which can highly hinder their further value-added applications. Firstly, the wood fiber cell walls will be modified coordinately by the immobilized enzymes and the chemicals in this project. The contents and distribution of components in fiber cell walls are controlled in purpose, and the characteristics of functional groups and charges inside are adjusted. Then, some modern instruments and techniques, such as Confocal Laser Scanning Microscopy (CLSM), X-ray Photoelectron Spectroscopy (XPS) and Fiber Mechanical Performance Analyzer, will be used, to measure the ultra-structure, chemical composition and fiber characteristics of wood fibers. The evaluation system for the deformation properties of HYP fibers will be constructed. Further, the interpretation regarding the effect mechanisms of the ultra-structure of wood fiber cell walls to its deformation properties will be obtained by analyzing mathematical models. Subsequently, the controlling mechanism to balance the bulk and bonding characteristics of fiber network will be proposed from the point of fiber deformation properties. Finally, the HYP fines will be modified by the immobilized enzymes and the chemicals, and added into long-fiber system to clarify the interactions between the fiber deformation properties and the bonding characteristics (or the bulk) of fiber network. In a word, the theories on the wood fiber separation can be enriched and developed through the researching conclusions in this project, and the basic technical foundations can be provided to produce wood fibers with relatively high physical properties and to enlarge their value-added applications in more paper grades and other fiber engineering fields.

木质纤维的形变性能直接影响其结合能力和纤维基产品的各项光学与物理性能。基于物理和化学方式解构的高得率浆纤维的结合性能与其松厚度之间存在显著反比关系，大大限制了其高值化应用。本项目拟采用固定化生物酶和化学试剂协调修复木质纤维细胞壁结构，对其成分含量与分布进行可控操作，调整其基团与电荷特性；运用共聚焦激光扫描显微镜、X射线光电子能谱、纤维力学性能测试仪等先进仪器和手段，探明木质纤维超微结构、化学组成与纤维性能，构建适用于高得率浆纤维的形变性能评价体系；通过数学模型分析揭示木质纤维细胞壁超微结构对其形变性能的响应机理，进而从纤维形变性角度提出纤维网络的松厚度与结合性能调控机制；通过回填经改性的高得率浆细小组分，剖析纤维形变性与其结合性能和松厚度的构效关系。本项目的研究成果将丰富和发展木质纤维解构工艺理论，为生产高性能纤维并扩大其在更多纸种及其他纤维材料领域中的高值化应用提供理论基础和技术依据。

木质纤维的形变性能直接影响其结合能力和纤维基产品的各项光学与物理性能。高得率浆纤维的结合性能与其松厚度存在对立关系，大大限制了其高值化应用。本课题评价了高得率浆纤维的结构特征、化学组成和纤维表面性能，探讨了几个关键因素对纤维形变性能的影响机制；利用化学和生物手段调控纤维细胞壁的不同化学成分比例和分布，构建木质纤维形变性能评价体系；采用“液桥”模型测定纤维接触角用于计算表面自由能（表征表面润湿性），明确了纤维表面润湿性对其形变性和结合性能的关系；通过建立数学模型分析高得率浆纤维形变性能与其结合性能的构效关系；借助Page方程探讨纤维表面摩擦性能与其形变和结合性能的响应关系；研究了不同类型纤维素基细小组分对改善纤维间结合性能的作用行为。研究表明：利用漆酶介体体系和亚氯酸钠处理高得率浆纤维以搭建木素成分在细胞壁中不同区域分布的纤维模型（外层木素含量6.91%，内层木素含量13.57%），采用高阳离子助剂可以改善生物酶的吸附（从29.9%提高至63.1%）；当总木素含量约为5%时，亚氯酸钠处理的纤维柔软性比结合亚氯酸钠与漆酶介体处理的纤维柔软性高1.559×109 N-1•m-2，即纤维细胞壁内层木素含量对纤维的柔软性影响较大；随着纤维表面润湿性增强，RBA增加，纤维形变性明显提升（柔软度从4.44×108N-1•m-2提高到1.18×109N-1•m-2），B从4.6 N•m•g-1提高至10.9 N•m•g-1。随着化学和生物处理强度的加深，纤维总木素含量和表面木素浓度均减少，纤维剪切结合强度b提高12MPa左右，纤维形变性能增强致使相对结合面积增大约30%，纤维结合强度指数B显著上升；当纤维表面自由能增加30.74%时，纤维表面动摩擦系数可提高134.62%，静摩擦系数提高92.11%，进而纤维形变能力和结合性能增大。利用功能化细小组分提高高得率浆纤维结合强度的同时，一定程度保持较高松厚度。上述科研成果丰富和发展了植物纤维性能评价手段，对于深刻理解高得率浆纤维形变性能、从纤维材料的形变角度改善纤维间结合性能与松厚度以扩大其在纤维材料领域的广泛应用提供了良好的基础理论依据。