Introduction of oxygen‐containing functional groups to carbon fiber surfaces to enhance the bending strength of PA6 ‐based carbon‐fiber‐reinforced thermoplastics

Abstract Carbon‐fiber‐reinforced thermoplastics (CFRTPs) are recyclable composite materials with excellent mechanical properties. However, for CFRTPs to be used in automobile applications, enhanced mechanical properties are required. To meet this challenge, the surface adhesion between the carbon fibers and thermoplastics must be improved. In this study, we developed surface treatment techniques for carbon fibers using the radical initiator dimethyl 2,2′‐azobis(2‐methylpropionate) (V‐601) to introduce oxygen‐containing functional groups to the carbon fibers through radical chemical reactions. Using x‐ray photoelectron spectroscopy, we showed that the surface adhesion between the carbon fibers and a nylon thermoplastic resin (PA6) improved owing to hydrogen bonding with carbonyl groups on the carbon fiber surface, which enhanced the mechanical properties of the CFRTP. Moreover, we demonstrated control of the mechanical properties of the CFRTP by varying the V‐601‐acetone concentration. The findings of this study can be used to develop automobile applications for PA6‐based CFRTPs. Highlights Carbon‐fiber‐reinforced thermoplastics (CFRTPs) have good mechanical properties. Surface adhesion between carbon fibers and thermoplastic resin PA6 was improved. Surface treatment techniques for carbon fibers were developed. Dimethyl 2,2′‐azobis(2‐methylpropionate) (V‐601) was used for this.