In this study, a multiscale cellulose fiber interlayer consisting of chopped flax fibers (FFs) and cellulose nanofiber (CNFs) was proposed for enhancing the interlaminar fracture toughness of carbon fiber/epoxy composites. The cellulose fiber interlayer was treated by waterborne epoxy to improve the interfacial compatibility with the epoxy matrix. The end-notched flexure results showed that the addition of the cellulose fiber interlayer in the carbon fiber/epoxy composites resulted in a remarkable increase in Mode II interlaminar fracture toughness, which was attributed to a synergistic effect of the FFs and the CNFs. The 3D network of the chopped FFs alleviated the agglomeration of the CNFs due to their good compatibility, leading to more fiber bridging and fiber pull-out during delamination. The presence of CNF further improved the interfacial properties of the FFs and epoxy matrix, which are beneficial for the fibrillation of flax fiber to hinder interlaminar crack growth.

在这项研究中，提出了一种由短切亚麻纤维 (FFs) 和纤维素纳米纤维 (CNFs) 组成的多尺度纤维素纤维夹层，用于提高碳纤维/环氧树脂复合材料的层间断裂韧性。纤维素纤维夹层采用水性环氧树脂处理，以提高与环氧树脂基体的界面相容性。端部缺口弯曲结果表明，在碳纤维/环氧树脂复合材料中添加纤维素纤维夹层导致模式 II 层间断裂韧性显着增加，这归因于 FF 和 CNF 的协同作用。由于其良好的相容性，短切 FF 的 3D 网络减轻了 CNF 的团聚，导致在分层过程中更多的纤维桥接和纤维拉出。