增塑熔融纺丝制备热塑性增韧纤维及其基于反应诱导相分离层间增韧液体成型复合材料的机理

Advanced carbon fiber composites prepared by liquid composite molding (LCM) is vital for the development of the aviation composites. However, the application of LCM is somehow limited mainly due to the poor anti-impact damage properties of the composites prepared by LCM. In this project, the regulation mechanism of the modified polyethersulfone (PES) and the epoxy resin will be explored carefully. Based on our previous results, the epoxy resin could reduce the melt processing temperature of the modified PES significantly. Therefore, we would adopt the modified PES to prepare the thermoplastic toughening fibers and fabrics through plasticized melt spinning, taking epoxy resin as a plasticizer. The thermoplastic fibers and fabrics could be used to interlayer toughen the epoxy resin matrix carbon fiber composites prepared by LCM. The structures and properties of the thermoplastic toughening fibers could be controlled by the systematic approaches of the plasticized melt spinning process. In order to clarify the the mechanism of the epoxy reaction induced PES phase separation, we would also analyse and identify the dissolution kinetics of the thermoplastic toughening fibers and the corresponding phase separation behaviors of PES in much detail during the solidification of the epoxy resin. The correlations among the LCM process, the particular microscopic phase structures of the interlamination and the macroscopic mechanical properties of the composites would be demonstrated after a systematic study and deep analysis. We expect to shed light on the mechanism of the thermoplastic fibers interlayer toughening the epoxy resin reinforced carbon fiber composites prepared by LCM base on the epoxy resin reaction induced PES phase separation. In this project, a progressive and high performance interlayer toughening technology for LCM composites would be realized based on the regulation and controlling the dissolution and phase separation process of the thermoplastic toughening fibers in epoxy resin. This technology would not only improve the interlayer toughness of the composites prepared by LCM but also could effectively resolve the undesirable processing properties for LCM composites in comparison with the traditional toughening methods. Ultimately, it might provide a theoretical principle and technically valid route for the advanced aviation composites prepared by the LCM.

液体成型（LCM）制备先进复合材料是航空复合材料发展的重要方向。目前，LCM制备的复合材料存在抗冲击损伤能力差的缺点，限制了其应用。本项目拟通过改性使聚醚砜可与环氧树脂相容，通过深入研究环氧树脂增塑改性聚醚砜的熔融纺丝机理及纤维结构与性能的调控机制，制备用于环氧树脂基碳纤维复合材料液体成型的热塑性增韧纤维及其织物。通过深入研究热塑性增韧纤维在环氧树脂固化过程中的溶解动力学及相分离行为，解析改性聚醚砜基于环氧反应诱导相分离的机理。系统研究复合材料液体成型工艺-层间微观相结构-宏观力学性能的关联机制，掌握热塑性纤维层间增韧液体成型环氧基碳纤维复合材料的机理。项目拟建立通过调控热塑性增韧纤维溶解及其相分离的机制，实现液体成型复合材料高性能的层间增韧，既可显著提高复合材料的层间韧性，又有效解决了传统复合材料增韧方法中液体成型的工艺性能问题，为液体成型制造高性能航空复合材料结构提供理论基和技术路线。

液体成型（LCM）制备先进复合材料是航空复合材料发展的重要方向。目前，LCM制备的复合材料存在抗冲击损伤能力差的缺点限制了其应用。本项目从动力学和热力学的角度上系统研究了环氧树脂与聚醚砜树脂的相容性，通过分析热塑性聚醚砜在环氧树脂固化初期的溶解行为及其在环氧树脂固化后期的相分离行为，掌握了聚醚砜基于反应诱导相分离对环氧树脂的增韧机理。在此基础上，利用环氧树脂对聚醚砜的增塑作用，深入研究了环氧树脂与聚醚砜的增塑熔融纺丝机理及其纤维结构与性能的调控机制，制备了可溶解于环氧树脂的聚醚砜纤维；并通过热塑性聚醚砜纤维与碳纤维混编和直接将聚醚砜纤维制备成具有规则结构的网纱置于碳纤维铺层织物层间，系统研究了聚醚砜纤维层间增韧液体成型环氧树脂基复合材料的结构与性能，深入分析了复合材料液体成型工艺-层间微观相结构-宏观力学性能的关联机制，掌握了热塑性纤维层间增韧液体成型环氧树脂基碳纤维复合材料的机理。研究发现，将聚醚砜制备成纤维与碳纤维混编或者制成纤维网纱置于碳纤维织物层间，一方面环氧树脂中没有增韧材料，可有效降低树脂体系粘度，有利于对织物的浸润，且不会影响液体成型工艺；另一方面热塑性纤维在环氧固化初期迅速溶解，并在固化后期通过相分离形成可控热塑相，通过塑性形变和裂纹偏转等机制大幅度提高复合材料的抗冲击损伤能力。由此，本项目通过调控热塑性增韧纤维溶解及其相分离机制，建立了通过热塑性纤维来实现复合材料液体成型的高性能层间增韧技术，即可显著提高复合材料的层间韧性，又有效解决了传统复材增韧方法中液体成型的工艺性能问题，有望在国产大飞机和高铁以及船舰等液体成型碳纤维增强环氧树脂基复合材料的结构中实现应用。