Electrophoretic Deposition of Chitosan-modified Carbon Fiber to Enhance Hygrothermal and Mechanical Properties of Carbon Fiber/Polyamide 6 Composites

The surface of carbon fiber (CF) was modified by the electrophoretic deposition of cationic chitosan (CS), which is expected to enhance the hygrothermal and mechanical properties of carbon fiber/polyamide 6 (CF/PA 6) composites. Carbon fiber in various treatment stages was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, and X-ray diffraction. The studies demonstrate that the chitosan-modified carbon fiber (CS-CF) increases the surface chemical activity and roughness of carbon fiber, which enhances the chemical bonding and mechanical interlocking of carbon fiber with PA 6. Compared with desized carbon fiber (D-CF), the O/C composition ratio of CS-CF increased from 20.34 % to 50.86 %, and the tensile strength and flexural strength of the CS-CF/PA 6 composites were enhanced by 50.31 % and 43.88 %, respectively. In addition, the hygrothermal properties of CS-CF/PA 6 were also improved. Fracture observation of the composite cross-sections further elucidates the mechanism of interfacial strengthening.