Microwave Absorption Performance of Carbon Black/Polylactic Acid Composite for Fused Filament Fabrication

To prepare lightweight, wideband, strong absorption and low-cost microwave absorbing materials, carbon black/polylactic acid (CB/PLA) composite filaments were prepared using a high-energy mixer and twin-screw extruder. Coaxial ring test pieces were printed by fused filament fabrication (FFF) technology with polylactic acid as the matrix and carbon black as the absorbent. The crystal texture and micromorphology of the composites were observed by XRD and SEM. The electromagnetic parameters were measured at 2–18 GHz using a vector network analyzer. The influence of CB content on the absorbing performance of the composites was studied, and the loss mechanism was explained. The results show that when the CB content (refers to PLA) is 25%, the composite has suitable impedance matching, conduction loss, and polarization loss, resulting in the best microwave absorption performance. The minimum reflection loss reached −45.47 dB at 13.68 GHz, and the corresponding effective absorption bandwidth was 5.36 GHz (10.72–16.08 GHz) with a matching thickness of 2.1 mm. At the same time, the density of the composite was only 1.19 g/cm3. This work sheds light on the development of lightweight and high-efficiency microwave absorption materials (MAMs) in a simple and low-cost manner.