Preparation and properties of hybrid specific length carbon fiber thermoplastic composites by suspension method

Abstract

Carbon fiber reinforced thermoplastic composites have such advantages as low density, high strength, high temperature resistance, impact resistance, and good ductility, but due to the density difference between carbon fibers and resin fibers, it is difficult to mix them uniformly. Hence, it is difficult to prepare the composites with the uniform properties. In order to solve this problem, a preparation process based on solid phase mixing of carbon and resin fibers by suspension method is proposed in this paper. The carbon fiber reinforced thermoplastic composites (CFRTPs) can be prepared by dispersing carbon fibers of a certain length (~50 mm) and resin fibers in suspension through ultrasound‐assisted and churn‐combing methods. The effects of carbon fiber length, content and molding process on the mechanical properties of the CFRTPs were studied. The results show that the carbon fiber content and length are the main factors affecting the mechanical properties as well as void ratio of CFRTP. The performance of composites is significantly improved with the increase of carbon fiber length. While the length of carbon fiber is 50 mm and the content is 30 wt%, the prepared CFRTP has the best performance, with the tensile strength of 182.1 MPa, the bending strength of 354.3 MPa, the impact strength of 67.2 KJ·m−2, and the material void ratio of 0.65%. The study shows that the suspension method is feasible for the preparation of the CFRTPs. It is beneficial to improve production efficiency and decrease cost of production for the CFRTPs.Highlights Carbon fiber reinforced thermoplastic composites can be prepared by dispersing carbon fibers of a certain length (~50 mm) and resin fibers in suspension through ultrasound‐assisted and churn‐combing methods. Through the cooling‐high pressure molding process, the porosity of CFRTP is reduced and the mechanical properties of CFRTP are improved. The tensile strength, bending strength, and notch‐free impact strength properties of CFRTP are best when the carbon fiber content is 30% and the CF length is 50 mm. The method is characterized by simple process, low cost and high mechanical properties.