Three-dimensional printing of recycled carbon fiber spun yarn reinforced polyamide

The three-dimensional (3D) printing of recycled carbon fiber was demonstrated by the fused filament fabrication technique. A recycled carbon fiber spun yarn was processed into a filament for 3D printing using polyamide 6 and polyamide 12 as the matrix. The fibers were aligned in the axial direction of the filament, and the filament followed the print path during 3D printing. Four specimens were prepared from the filament by 3D printing. The effect of the 3D printing process on the tensile properties of the recycled carbon fiber filament was evaluated. The comparison of the four specimens showed that the 3D-printing process adversely affected the tensile properties of the composite by damaging the fibers and dispersing the fiber direction. Multiplying the filament compensated for the variability in the tensile properties and improved the tensile properties of the 3D-printed coupon. The 3D-printed recycled carbon fiber-reinforced polyamide showed intermediate properties between those of 3D-printed continuous and milled carbon fiber composites. 3D printing is an effective molding technique for the use of recycled carbon fibers.