Dongxing Zhang

The primary challenges in utilizing thermoplastic poly(ether‐ether‐ketone) (PEEK) stem from its inherent lack of toughness in production settings. Traditional methods of enhancing toughness often compromise other essential properties of the material. This research focuses on optimizing the toughness of PEEK resin composites by integrating graphene oxide (GO) and silicone rubber (SR) particles into the PEEK matrix to formulate multiphase composites. A detailed investigation was carried out to assess the impact of these two distinct particles on the PEEK resin properties. In the evaluation of toughness across various composite materials, a notable enhancement was evident in the GO/PEEK, SR/PEEK, and GO/SR/PEEK ternary composites compared to the pristine PEEK. Furthermore, these composites maintained comparable stiffness and thermal resistance to standard PEEK. Tensile strength, fracture absorbed energy, and fracture toughness in GO/SR/PEEK ternary composites versus pure PEEK indicated increases of 18.38%, 174.53%, and 46.37%, respectively. Fracture analysis demonstrated that multi‐particle modification methods significantly complicated toughening mechanisms, including rubber voiding, matrix shear band formation, crack deflection, and matrix plastic deformation. The findings from this study propose a viable material design principle for engineering materials that effectively balance strength and toughness.Highlights: The GO/SR/PEEK composites with a balance between strength and toughness. GO and SR exert a synergistic effect on the mechanical properties balance of PEEK. The plastic deformation is promoted as the main toughening mechanism. GO and SR enhanced PEEK crystallization, improving its mechanical properties.

To date, carbon fiber (CF) reinforced polymer composites have found widespread application due to exceptional properties, including high specific strength and modulus, thermal stability, chemical durability. However, the interface serves as the bridge for load transfer between fiber and resin, the interfacial property directly affects the holistic performance of the composites. Therefore, considering the inertness of CF and polyetheretherketone (PEEK), and the modulus gap between them, we propose a flexible-rigid sizing agent for enhancing the interfacial adhesion and mechanical properties of CF/PEEK composites. The sizing layers are constructed by the hybrid nanoparticles of rare-earth coordination bonded flexible aramid nanofiber (ANF) and rigid nano-TiO₂, and the transition layer of polyetherimide (PEI). The treatment with the flexible-rigid sizing agent significantly improves the active functional group content, surface roughness, and wettability of the CF. Meanwhile, as-prepared CF/PEEK composites show a remarkable enhancement both in mechanical and interfacial strength, which could be attributed to the synergistic effects of flexible-rigid structures, ultimately improve the external stress transfer and suppression of crack propagation. Herein, this work offers a robust and promising approach for the fabrication of high-performance CF/PEEK composites.