ABSTRACT Polyetherimide (PEI) modified long carbon fiber (LCF) reinforced poly(ether ether ketone) (PEEK) composites were fabricated using a solution impregnation technique. Processing parameters were systematically optimized through orthogonal experimental design. The influence of carbon fiber length on the mechanical properties, thermal behavior, crystallization characteristics, and microstructure of the composites was thoroughly investigated. Scanning electron microscopy (SEM) revealed uniform dispersion of carbon fibers within the PEEK matrix and a certain three‐dimensional fiber orientation. These structural features contributed to outstanding mechanical performance, with maximum recorded values of 335 MPa in tensile strength, 343 MPa in flexural strength (LCF/PEEK‐10 mm), and 232 kJ·m −2 in Charpy impact strength (LCF/PEEK‐3 mm). The introduction of PEI significantly improved fiber‐matrix interfacial adhesion, facilitating enhanced resin impregnation. These high‐performance lightweight composites demonstrate considerable potential for advanced applications in aerospace, biomedical implants, and industrial manufacturing.
Liu et al. (2026) studied this question.