A Novel Suspension for Rapid, Continuous PEEK Impregnation of Sized Large‐Tow Carbon Fibers

ABSTRACT Carbon fiber reinforced polyetheretherketone (CF/PEEK) composites possess excellent mechanical properties and thermal stability. However, during the processing of PEEK with large‐tow carbon fibers, there are challenges such as dense fiber arrangement and high viscosity penetration of the resin, which usually require complex fiber spreading or surface treatment. In this work, a novel aqueous suspension‐based impregnation process is developed to rapidly and continuously impregnate epoxy‐sized large‐tow carbon fibers with PEEK without any prior desizing or tow spreading. The suspension utilizes a multicomponent gradient‐evaporation solvent system (deionized water with ethanol, ethylene glycol, and NMP) combined with synergistic surfactants (PVP K30, PEG‐400, and Tween 80) to dramatically improve resin powder dispersion stability and lower interfacial tension. The addition of nano‐SiO ₂ and a silane coupling agent (KH560) further enhances fiber–matrix interfacial bonding. Zeta potential analysis confirmed that the optimized suspension (pH 9, 1.5 wt% surfactants) achieved high stability with no observable sedimentation for 1 h, and contact angle tests showed effective wetting on sized fibers (only 2° difference from desized). Using a custom continuous impregnation line, 48K tows were uniformly coated and consolidated at 1 m/min line speed. The resulting prepregs exhibited uniform resin distribution with fiber volume fractions of approximately 35% and porosity below 1%. A three‐hour continuous production run demonstrated consistent prepreg quality over time. These results highlight that the proposed multicomponent suspension and process enable fast, continuous manufacturing of high‐quality CF/PEEK prepregs from large‐tow fibers without additional fiber treatment, representing a significant advancement in scalable thermoplastic composite fabrication.