High Interfacial Shear Strength and High Tensile Strength in Heterocyclic Aramid Fibers with Improved Interchain Interaction

As a typical kind of high-performance fibers, heterocyclic aramid fibers are widely used to reinforce resins to prepare advanced lightweight composites with high mechanical performances. However, their poor interfacial shear strength limits the combination with resins and leads to undesirable interfacial strength of composites. Thus, heterocyclic aramid fibers with high interfacial shear strength and high tensile strength are highly desired. Herein, heterocyclic aramid fibers with a high interfacial shear strength of 40.04 +/- 2.41 MPa and a high tensile strength of 5.08 +/- 0.24 GPa are reported, in which the nitrile-modified poly-(benzimidazole-terephthalamide) polymer chains are crosslinked by azide-functionalized graphene oxide nanosheets. The improved interchain interaction can conquer the splitting of nanofibrils and strengthen the skin-core layer of heterocyclic aramid fibers, while the graphene oxide can induce an ordered arrangement of polymer chains to improve the crystallinity and orientation degree of fibers. These two effects account for the high interfacial shear strength and high tensile strength of heterocyclic aramid fibers. These findings have provided a strategy to efficiently enhance the interfacial shear strength as well as the tensile strength of high-performance fibers. The small addition of GO-N3 can not only improve the interchain interaction to conquer the splitting of nanofibrils and strengthen the skin-core layer of fibers, but also improve the crystallinity and orientation degree of GO-N3/PBIA-CN fibers, leading to the preparation of GO-N3/PBIA-CN fibers with high interfacial shear strength and high tensile strength.imag