Parameter design of continuous carbon fiber-reinforced phenolic resin composites via in situ-curing 3D printing technology

To improve the print quality and mechanical properties, the process parameters of the continuous carbon fiber -reinforced phenolic resin (CF/PF) composites were systematically investigated based on the in situ -curing 3D printing technology. The printing spacing and printing thickness affected the bonding between fiber bundles. Under the optimized parameters, the surface of the CF/PF composites was smooth and flat, without obvious gaps between the adjacent prepregs and printing layers. Especially, we optimized the resin impregnation temperature (T-i) and analyzed the influence mechanism on mechanical properties. With the increasing impregnation temperature, the resin content and the squeezing force applied to fiber bundles decrease, while the wettability between fiber and resin increases. The resin contents and the squeezing force play more important role on the mechanical properties of the CF/PF composites. With the combined influence of the above effects, the flexural strength of CF/PF composites reaches maximum value of 471.1 MPa under the impregnation temperature of 30 degrees C, printing spacing of 0.80 mm, and printing thickness of 0.10 mm, with minimum defect volume, uniform distribution of fiber and resin, and appropriate fiber/resin interaction.