Molecular Structure Design of Sizing Agent and Its Influence on the Mechanical Properties of CF Reinforced Composite

In this article, phosphate modified epoxy resin (PAEK) and polyethylene oxide (PEO) were used as the main monomers to fabricate a composite sizing agent (TPP) for carbon fiber (CF) surface treatment. The effects of TPP sizing on the surface morphology, activity and wettability of CF were studied by FE-SEM, XPS and contact angle. In addition, friction coefficients, fuzz amount and the mechanical properties of CF filaments, as well as the interlaminar shear strength (ILSS) of CF composites were analyzed. The results indicate that the defects of CF surface were completely repaired by TPP molecules, the content of active groups increased by 24.8 % and the contact angle and the spreading time of EP on CF surface reached respective minimum values of 43.5 ° and 15 s, meanwhile, the friction coefficient and the fuzz amount of the treated CF surface are reduced in the sizing quantity range of 3.0–4.0 mg/g. Thus, there were 36.1 % and 24.3 % enhancement in the breaking strength and elongation of CF filament. In addition, the ILSS of composite prepared with TPP treated CFs was increased from 12.81 to 28.55 MPa.