Study on the construction of polyethyleneimine/nano-silica multilayer film on the carbon fiber surfaces to improve the interfacial properties of carbon fiber/epoxy composites

ABSTRACT

To enhance the interfacial properties of carbon fiber (CF) reinforced epoxy composites without damaging the CF strength. The polydopamine (PDA) was used as the precursor layer, and polyethyleneimine (PEI) and nano-silica (nano-SiO₂) were deposited on the surface of CF by layer-by-layer electrostatic self-assembly. The layered strengthening materials (CF-Ln) were prepared and the microstructure of the CF was systematically characterized. The results showed that when the number of self-assembled layers is 5 (CF-L5), nano-SiO₂ covers the surface of CF uniformly, and the tensile strength of CF-L5 monofilament reaches the maximum value, which is 12.1% higher than that of untreated CF (U-CF). Meanwhile, the interface properties between CF-L5 and epoxy matrix have been significantly improved. The interfacial shear strength (IFSS) between CF-L5 and epoxy matrix is 99.4% higher than that of U-CF. The improvement of the interfacial properties between CF-L5 and epoxy matrix is due to the introduction of alarge number of active groups (-NH₂, -OH) in the PEI/SiO₂ multilayer film deposited on the surface of CF, which improves the wettability between the CF and epoxy matrix. Also, the nano-SiO₂ increases the roughness of the CF surface and improves the mechanical engagement between the CF and epoxy resin.

Graphical abstract

KEYWORDS:

• Carbon fiber
• surface modification
• layer-by-layer self-assembly
• nano-silica
• interfacial properties

Disclosure of potential conflicts of interest

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The funding source for this work is the Natural Science Foundation of China, project number: 51708553;the Natural Science Foundation of China [51708553];the Natural Science Foundation of China [51708553];