The crosslinked polymers used in fibre composites are very brittle, and require toughening for structural applications. Research over many years has increased the fracture energy, but the fatigue resistance of these toughened polymers is very poor, limiting the optimisation of structures. This work reports the first successful use of hybrid toughening to increase both the quasi-static interlaminar fracture energy, G_IC, and the fatigue threshold strain-energy release-rate, G_th. Amine-cured epoxy glass-fibre composites were toughened using carboxyl-terminated butadiene-acrylonitrile (CTBN) which forms micron-sized rubber particles and 20 nm-diameter silica nanoparticles. The toughening mechanisms were identified as cavitation of rubber particles and debonding for the silica nanoparticles, followed by plastic void growth. The CTBN greatly increases G_IC, and the nanoparticles increase G_th. Combining both particles as a hybrid has a synergistic effect on the fatigue resistance. This demonstrates the effectiveness of hybrid toughening, enabling the design of optimised composites by combining micro- and nanoparticles.

纤维复合材料中使用的交联聚合物非常脆，需要对结构应用进行增韧。多年来的研究增加了断裂能，但是这些增韧聚合物的抗疲劳性非常差，限制了结构的优化。这项工作报告了首次成功使用混合增韧来增加准静态层间断裂能G _IC和疲劳阈值应变能释放速率G _th。胺固化的环氧玻璃纤维复合材料使用羧基封端的丁二烯-丙烯腈（CTBN）进行增韧，从而形成微米级的橡胶颗粒和直径为20 nm的二氧化硅纳米颗粒。增韧机理被确定为橡胶颗粒的空化和二氧化硅纳米颗粒的脱粘，然后是塑性空隙的增长。CTBN大大增加了G _IC，纳米颗粒增加了G _th。将两种颗粒混合在一起可对疲劳强度产生协同作用。这证明了混合增韧的有效性，可以通过将微粒和纳米颗粒结合在一起来设计优化的复合材料。