Characterizations of continuous carbon fiber-reinforced composites for electromagnetic interference shielding fabricated by 3D printing

With an increase in electromagnetic interference pollution, composites for electromagnetic interference shielding (EMIS) with good shielding performance and friendly processability are widely demanded. Herein, a methodology for preparing composites with controllable shielding effectiveness (SE) is proposed. Carbon fiber (CF)-reinforced polylactic acid composites were fabricated by a 3D printing process, and the SE of the composites was controlled by varying the process parameters. To systematically investigate the feasibility of the methodology, the shielding properties, processability, and mechanical properties of the composites were investigated. The results showed that the SE was controlled in the ranges of 25.1–69.9 dB, 51.1–75.6 dB, and 6.8–78.9 dB by tailoring the number of layers (2–12), hatch spacing (1.6–0.8 mm), and filling angle (90°–0°), respectively. The critical mechanism of the controllability is that the content, spatial distribution, and orientation of CFs can be facilely and digitally controlled during processing. A conformal shell with a SE of 38.5 dB was fabricated to demonstrate superior processability of a complex geometry. The maximum tensile and flexural strengths of the composites were 111.0 and 152.9 MPa, respectively, which were much larger than those of most engineering plastics. Using this methodology, an appropriate SE that is neither excessive nor deficient can be readily realized, which helps to maintain high resource utilization. Complex geometries for EMIS can be rapidly and cheaply obtained without molds, which is difficult for traditional processes. These advantages make the 3D-printed CF-reinforced composites competitive with other EMIS materials and traditional processes.