Polydopamine particle in-situ assisted carbon fiber/CNTs brush with dynamic imine bonds for enhancing the interface properties of its polyamide 6 composites

Fabricating carbon fiber/carbon nanotubes (CF/CNTs) brush is regarded as an effective way to improve its composite interfacial and mechanical properties. Different from other reports, a novel fabrication method was developed in this work. Based on Schiff base reaction, polydopamine (PDA) particle with moderate size could in-situ assist CNTs hairs to be grafted onto carbon fibers surface under agitation condition. This method can guarantee thermal stability of modified layers and facilitate the interfacial compatibility of CF/PA6 due to dynamic imine bond exchanges under high temperature (240 °C) during the injection molding. The contact angle of modified CF with PA6 decreased to 34.2° from 53.6° of the untreated-CF. The results also showed both the interfacial and mechanical properties of the composites were improved. Compared with that of the untreated-CF/PA6 composites, the interfacial shear strength, tensile strength and tensile modulus of modified-CF/PA6 were increased by nearly 64.39%, 22.14% and 21.67%, respectively. This simple modification method would provide the premise to expand it to scale-up industry production of CF reinforced thermoplastic composites.