Silane‐Mediated Graphene Oxide Assembly and Interfacial Performance of Carbon Fiber/Epoxy Composites

ABSTRACT Carbon fiber/epoxy (CF/EP) composites are widely used in lightweight structural applications, but the fiber/matrix interface remains a critical factor governing their mechanical performance. This study investigated the relationship between silane‐modified surface states, graphene oxide (GO) assembly, and the interfacial response of T800 CF/EP composites. Oxygen plasma activation, silane modification, and GO deposition were sequentially applied, with KH550 and KH560, bearing different terminal functionalities, used to generate distinct surface states for subsequent GO deposition. Plasma treatment increased surface oxidation and improved the apparent wetting behavior of the CF tows. Under identical GO deposition conditions, GO appeared mainly as discrete deposits on KH550‐modified fibers, whereas more extensively distributed sheet‐like structures were observed on KH560‐modified fibers, which also showed greater morphological retention after controlled tape peeling. Mechanical controls showed that silane modification itself was associated with changes in the interfacial response. Subsequent GO incorporation further increased the mean apparent short‐beam strength from 40.92 to 43.63 MPa for the KH550 system and from 45.84 to 52.18 MPa for the KH560 system. These results support an association among the silane‐modified surface state, GO assembly morphology, and interfacial response, with the final performance reflecting the combined contributions of silane modification and subsequent GO assembly.