Interface‐Engineered Long Glass Fiber Reinforced PA6 Composites: Multi‐Scale Effects of POE‐g‐MAH on Structure and Properties

ABSTRACT Achieving optimal fiber impregnation and robust interfacial adhesion is critical for long glass fiber‐reinforced polyamide 6 (LGF‐PA6) composites. In this study, a high‐flow branched PA6 resin was synthesized to enhance impregnation efficiency. A multi‐scale interfacial architecture was subsequently engineered using APTES‐functionalized fibers and POE‐g‐MAH compatibilizer. Investigations revealed that loading POE‐g‐MAH established a robust organic–inorganic interface via covalent and hydrogen bonds dual‐mode bonding. Nanomechanical mapping confirmed the formation of a gradient interfacial transition zone of 449 nm, which effectively induced crystallization and refined the crystalline morphology. Consequently, the 30 wt% LGF‐PA6 composites achieved peak performance, featuring a tensile strength of 185 MPa and exceptional impact resistance at −40°C, alongside enhanced surface scratch resistance. These findings demonstrate that precise multi‐scale interfacial tuning, spanning molecular‐level bonding, interphase nanomechanics, and crystalline architecture, represents a pivotal strategy for the design of advanced structural composites targeting lightweight engineering applications.