Microwave characterization of 3D printed PLA and PLA/CNT composites

The aim of this paper is to characterize dielectric properties of polylactic acid, one of the most commonly used materials for 3D-printing, at microwave frequencies, specifically at X-band. The knowledge of the complex permittivity of this plastic material is important for many applications. The manufacturing process of the printed object also requires to investigate the possible material anisotropy. Moreover, using polylactic acid doped with carbon nanotubes it is possible to manufacture conductive materials that can be used to realize electronic devices and microwave components. 3D-printed samples, based on the polylactic acid filament and polylactic acid filament doped with carbon nanotubes, were designed and manufactured by fused deposition modeling along three different axes, in order to characterize the material and examine also its possible anisotropic effect at microwave frequencies. Complex permittivity results were obtained from the scattering parameter data using the transmission line method and a suitable measurement model.