High-pressure interfacial impregnation by micro-screw in-situ extrusion for 3D printed continuous carbon fiber reinforced nylon composites

A micro-screw in-situ extrusion process was utilized to obtain high pressure for good impregnation and high fiber fraction of 3D printed continuous carbon fiber reinforced nylon (PA12) composites. Nylon pellets and different carbon fiber strand bundles (1 K and 3 K) were used as raw materials to print composites with different process parameters. Almost full impregnation for 1 K continuous carbon fiber (CCF) reinforced PA12 composites (1 K-CCF/PA12) with only 0.15% porosity and good impregnation for 3 K continuous carbon fiber reinforced PA12 composites (3 K-CCF/PA12) with 2.62% porosity achieved. Fiber volume fraction was dramatically improved from 31.9 vol% for 1 K-CCF/PA12 to 50.2 vol% for 3 K-CCF/PA12. Mechanical properties of different composites were measured systematically. Excellent longitudinal tensile strength and modulus of 735.7 MPa and 79.5 GPa, and simultaneously flexural strength and modulus of 772.6 MPa and 85.3 GPa for 3 K-CCF/PA12 were obtained. This novel 3D printing of continuous fiber reinforced composite process realized the integration of composites preparation and formation with enhanced impregnation, high fiber fraction and mechanical performance which could expand the applications of this technology to more and more industry fields.