Enhance the Interfacial Strength of Carbon Fiber/Epoxy Resin Composites Through a Polyaryletherketone Sizing Strategy Utilizing the Synergistic Effects of Hydrogen Bonding and π – π Interaction

ABSTRACT To improve the interfacial bonding performance of carbon fiber/epoxy resin composites (CFRP) and construct a stable and efficient interfacial transition structure, this study used aqueous polyaryletherketone (PAEK) emulsion to modify carbon fiber (CF). The results showed that an appropriate emulsion particle size facilitates the formation of a continuous and uniform polymer interfacial layer on the CF surface, thereby improving fiber surface roughness and wettability. With increasing emulsion content, the interfacial structure gradually evolved from a uniform thin layer to a locally aggregated structure. Notably, the tensile strength of CF‐PAEK 0.03 monofilament reached 3.30 GPa, and the interlaminar shear strength (ILSS) of the composite increased by 32%. Mechanistic analysis revealed that the aromatic structure in the PAEK molecular chain can form π – π interactions with the CF graphite microcrystals, while polar groups such as carbonyl groups can form hydrogen bonds with the epoxy resin (EP). These two components synergistically construct a stable noncovalent interfacial network, thereby promoting interfacial stress transfer and improving interfacial bonding strength. This study elucidates the synergistic mechanism of interfacial structure regulation and noncovalent interactions, providing a theoretical basis for the interfacial structure design and performance optimization of CFRP.