基于多级机械剪切剥离宏量制备竹纤维素纳米纤及其聚合物复合材料研究

本项目致力于将丰富的竹资源转化成高附加值的纤维素纳米纤（cellulose nanofibrils，CNF），研制竹CNF增强的高性能聚合物复合材料。针对目前机械法制备CNF存在高能耗，纤维素降解、结晶度降低等致使CNF性能下降的问题，根据宏观竹纤维的多层次结构特点，开发新型纤维素预处理技术，并设计制造具有强大剪切和剥离功能的"多级剪切机械剥离"装置。系统研究预处理和多级剪切机械剥离过程中竹纤维结构与形态演变，揭示多级剪切剥离制备竹CNF的机理。针对CNF在高分子复合材料应用中面临的分散问题和界面问题，开发基于力化学原理的一步法制备表面改性CNF的方法,通过熔融加工制备高性能CNF增强的聚合物复合材料。研究CNF在聚合物基体中的混合、分散和界面相互作用及复合材料结构与性能的关系。本项目的实施，将为竹CNF的宏量制备及应用提供新原理和新技术，对促进我国的纤维素纳米材料的发展具有重要意义。

This proposal focuses on the manufacturing of high value-added cellulose nanofibrils (CNF) from the abundant bamboo resources and developing high performance CNF reinforced polymer composites. The state-of-the-art technologies for mechanical nanofibrillation of plant fibers still have quite a lot of deficiencies, such as high energy consumption, severe degradation of cellulose, sharp decrease of crystallinity, which may deteriorate CNF's properties. To tackle these problems, novel pretreatment technologies coupled with the powerful multi-level mechanical shearing exfoliation equipment will be developed to directly target the hieratical ultrastructure of bamboo cellulose fibers. The morphological and structural alteration of bamboo fibers during pretreatment and multi-level mechanical exfoliation process will be systematically investigated to elucidate the underlying nanofibrillation mechanism. In addition, a one-step extraction and surface modification of CNF, which works under a mechanochemical mechanism, will be proposed to address the dispersing and interface problems when used in polymer composites. High performance polymer/CNF composites will be produced via melt processing. The mixing, dispersing and interface interactions in the composites, the relationship between structure and property of the composites will be studied. The implementation of this proposal is anticipated to generate some new theories and new technologies for large-scale productions of CNF as well as its applications in a large scale, which will ultimately lead to the fast growth of CNF material of our country.