3D Printing Technology for Short-continuous Carbon Fiber Synchronous Reinforced Thermoplastic Composites: A Comparison between Towpreg Extrusion and In Situ Impregnation Processes

Abstract

Three-dimensional (3D) printing of carbon fiber-reinforced thermoplastic composites (CFRTPs) provides an effective method for manufacturing the CFRTPs parts with complex structures. To increase the mechanical performance of these parts, a 3D printing technology for short-continuous carbon fiber synchronous-reinforced thermoplastic composites (S/C-CFRTPs) has been proposed. However, the synchronous reinforcement that existed only at particular positions led to a limited improvement in the mechanical performance of the 3D-printed S/C-CFRTP part, which made it challenging to meet the engineering requirements. To solve this problem, two methods for achieving synchronous reinforcement at all the positions of the 3D-printed S/C-CFRTP part are proposed. To determine a suitable printing process for the S/C-CFRTP part, a comprehensive comparison between the two methods was conducted through theoretical analysis and experimental verification, involving the printing mechanism, fiber content, impregnation percentage, and mechanical performance. The results indicated that the towpreg extrusion process was suitable for manufacturing the 3D-printed S/C-CFRTP part. Compared with the in situ impregnation process, the towpreg extrusion process led to a fiber content increase of approximately 7% and void rate reduction of approximately 6%, resulting in 19% and 20% increases in the tensile and flexural strengths of the 3D-printed S/C-CFRTPs, respectively. Additionally, an optimized process parameter setting for fabricating an S/C-CFRTP prepreg filament with excellent mechanical performance was proposed. The findings of this study can provide a new approach for further improving the mechanical performance of the 3D-printed advanced composites.