碳纤维表面双重刚柔结构可控构筑及其复合材料界面增强增韧机制研究

To construct an ideal modulus gradient transition interface layer is the critical problem on the composite properties. This project will achieve the objective through constructing a dual structure with rigid and flexible on carbon fiber (CF) surface and study the related mechanisms. The CNTs and polyamide branch chain will be grafted onto CF surface by esterification and anionic polymerization reaction to construct controllably the dual structures with rigid and flexible, and then the CF/epoxy composite will be prepared, the interface layer with multistage gradient modulus is intended to establish. The influence rules of grafting density, proportion and chain length of rigid and flexible structures on the microstructure and interfacial properties will be investigated and optimized. The synergistic roles of dual structure with rigid and flexible as well as the effects of modulus gradient variation on composites mechanical properties are going to be clarified. The interface strengthening and toughening mechanism will be explored. The project will lay a theoretical and practical foundation for the preparation of high-performance CF composites and the establishment of efficient interface control technology.

构筑理想的模量梯度过渡界面层是制备高性能树脂基复合材料的关键问题。本项目提出通过构筑具有“刚柔并济”特性的碳纤维表面结构来实现复合材料界面层的模量多级梯度过渡，并对其相关机理进行研究。通过将CNTs先接枝到碳纤维表面，再将聚酰胺支链通过阴离子聚合法接枝到碳纤维和CNTs表面，构筑表面具有可控双重刚柔结构的碳纤维，以环氧树脂为基体制备复合材料，从而构建多级梯度模量过渡的界面层。研究刚柔结构接枝密度、比例及链长变化对界面相微观结构及界面性能的影响规律并进行优化，探讨双重刚柔结构的协同作用和界面相模量梯度变化对复合材料宏观力学性能的影响规律，重点阐述其界面增强增韧机制，为制备新型高性能碳纤维复合材料及建立高效的复合材料界面控制技术奠定理论和实践基础。

面向目前航空航天武器装备轻量化重大需求，针对碳纤维增强树脂基复合材料界面性能与冲击韧性不可兼顾的难题，本项目通过将CNTs先接枝到碳纤维表面，再将聚酰胺支链通过阴离子聚合法接枝到碳纤维和CNTs表面，构筑了具有双重“刚柔并济”特性的碳纤维表面结构，双重刚柔结构是指横向刚柔结构和纵向刚柔结构，横向刚柔结构可平衡缓冲纤维与树脂的模量，纵向刚柔结构可增加与树脂的相容性，从而构建了复合材料界面层的模量多级梯度过渡，复合材料的界面剪切强度和冲击强度分别提高了75.6%和34.6%，突破了碳纤维/树脂基复合材料界面性能和冲击韧性不可兼顾的难题。本项目还研究了刚柔结构中不同刚性结构、不同柔性结构以及不同界面相厚度等对复合材料界面相微观结构及界面性能的影响，探讨了双重刚柔结构的协同作用和界面相模量梯度变化对复合材料宏观力学性能的影响规律，深入挖掘了碳纤维表面结构与复合材料界面相结构及复合材料界面和整体性能的关系，揭示了界面增强增韧机制，这为改善纤维增强树脂基复合材料界面微观结构及性能提供了理论基础。