(1. School of Ship Engineering, Dalian University of Technology, Dalian 116024, China)
（2. Collaborative Innovation Center of High Tech Ship and Deep Sea Development Equipment, Shanghai 200240, China）
（3. State Key Laboratory of Industrial Equipment Structure Analysis, Dalian 116024, China)
3D printing continuous carbon fiber reinforced thermoplastic composites (CCFRTPCs) are widely used in various fields because of their advantages of light weight and high strength. In the printing process of the composites, carbon fiber is used as the reinforcement, and the interfacial bonding between carbon fiber and resin is the key factor affecting the mechanical properties of materials. Pretreatment of continuous carbon fiber to enhance the interfacial properties between fiber and resin is a current research hotspot. In order to improve the mechanical properties of 3D printing continuous carbon fiber reinforced polycarbonate (PC) composites, firstly, different concentrations of waterborne PC sizing agent were used to size the continuous carbon fiber precursor. And the influence of sizing agent concentration on continuous carbon fiber sizing was studied. Then, using PC as matrix, continuous carbon fiber precursor and prepreg with different sizing amount as reinforcement, the surface morphology of continuous carbon fiber before and after sizing was observed and compared, and the influence of sizing treatment on the interfacial and mechanical properties of the composite was analyzed. The results showed that with the increase of sizing agent concentration, the sizing amount of continuous carbon fiber increases, but the increase rate slows down. After sizing, the surface roughness of continuous carbon fiber increases, and the interfacial bonding between internal monofilaments is improved. The results showed that the mechanical properties of the fiber prepreg composites with different sizing amount are better than those of the fiber precursor composites. In this paper, the optimal sizing amount is 29.59% corresponding to a 40% concentration of sizing agent. Compared with carbon fiber precursor composites, the flexural strength, flexural modulus, tensile strength, interlaminar shear strength and impact strength of the 29.59% prepreg composites increased by 15.82%, 75.58%, 90.9%, 57.22% and 56.45%, respectively.