An Aqueous Powder‐Slurry Method to Prepare Prepreg Filament for 3D Printing: Effects of Polyamide Solid Content, Surfactant Concentration, and Pulling Speed on Resin Pick‐Up

Prepreg filament is the feedstock for continuous carbon fiber reinforced thermoplastic 3D printing, and its quality is critical. In this work, an aqueous powder‐slurry method to prepare prepreg filament was proposed, in which the carbon fiber tow was impregnated using an aqueous powder‐slurry composed of deionized water, polyamide (PA) particles, surfactant, and additives. In this process, resin pick‐up governs both the stability of prepreg filament fabrication and the performance of the prepreg filament. A 27‐run full‐factorial design was employed to investigate the effects of PA solid content, surfactant concentration, and pulling speed on resin pick‐up, resin distribution, and porosity. A resin pick‐up mechanism consisting of infiltration, expulsion, and coating stages was established. Based on analysis, the optimal parameter combination was identified as 40 wt% PA solid content, 1 wt% surfactant concentration, and 5 mm/s pulling speed. Under this condition, the semi‐finished PPF satisfied the minimum resin pick‐up requirement while exhibiting continuous surface resin coverage, uniform axial resin distribution, a rounded cross‐sectional profile, and low porosity. The prepreg filament prepared under this combination exhibited a tensile strength of 1013.9 MPa, demonstrating that the optimal combination can produce high‐quality filaments and validating the effectiveness of the aqueous powder‐slurry process.