High-Frequency Dielectric Behavior of Structural Variation Integrated 3D-Printed PLA

Polylactic acid (PLA) has emerged as a promising polymeric material for additive manufacturing, owing to its low cost, processability, biodegradability, and compatibility with electromagnetic and general engineering applications. Among various fabrication techniques, fused deposition modeling (FDM)-printed PLA has attracted particular interest as a substrate material for microwave antennas, where dielectric properties play a critical role in determining antenna performance, impedance matching, radiation efficiency, and resonant frequency. However, the influence of extruded materials and their corresponding internal structures on the dielectric behavior of PLA has been limitedly explored. This study investigates the influence of FDM extrusion and design parameters on the dielectric behavior of additively manufactured PLA. We fabricated standardized test specimens in accordance with ASTM guidelines, with systematic variations in nozzle diameter, infill density, and infill structure, while maintaining consistent printing conditions for all other parameters. The dielectric behavior of the printed specimens was experimentally characterized using a dielectric measurement system over the frequency range of 100 Hz to 20 MHz. The experimental results reveal that the internal architecture generated during the FDM process significantly affects the dielectric response of PLA. It was found that adjustments in nozzle diameter, infill density, and infill geometry alter the material's internal porosity and air-volume fraction, leading to measurable changes in both dielectric constant and dielectric loss. This process–structure–property relationship was essential for demonstrating the electromagnetic characteristics of PLA that can be tailored through controlled manufacturing parameters without modifying the base material composition. The findings of the research offer valuable insights for the design and optimization of lightweight dielectric substrates for antennas and other high-frequency devices. Furthermore, this work supports the development of application-specific additively manufactured dielectric materials and highlights the potential of process-driven property engineering for advanced electromagnetic and multifunctional applications.