INSIGHTS FOR IMPROVING THE ELECTROMAGNETIC PROPERTIES OF CONDUCTIVE NANOCOMPOSITES MANUFACTURED WITH CARBON NANOTUBES

Additive manufacturing (AM) technologies offer many advantages that are attractive for electromagnetic compatibility (EMC) in industrial environments, and possibilities include customizable sizes and new complex internal shapes (infill) for parts. The polymeric nanocomposites with carbon-based nanomaterials, such as multi-walled carbon nanotubes (MWCNT), are of great interest and can be used for the development of functional electromagnetic components using the material extrusion (MEX) technique,. However, the literature lacks a deeper understanding of the relationship between the MEX process, the slicing parameters, the structure generated, and the electromagnetic behavior of the nanocomposite-based parts. This work studied the influence of building direction, various infill patterns, and orientations of acrylonitrile-butadiene-styrene copolymer (ABS)/MWCNT nanocomposite with 3wt% of MWCNT on the manufacture of samples by additive manufacturing, with the evaluation of the electromagnetic interference shielding effectiveness (EMI SE) and reflection loss (RL) performances of the prepared materials. The correlation between geometric parameters and the EM response was explored and corroborated with computational simulations. The results pointed out that parts using the building direction (ZX and XY) may achieve similar shielding results depending mainly on the infill orientation. When the deposited filament (or the entire layer) is aligned with the electric field, the EM shielding behavior is maximized. In contrast, when the deposited filaments are orthogonal to the electric field, the behavior is impaired. The computational simulation of the rheological flow of the nanocomposite and the EM behavior corroborated these findings, and the MEX sample matched the attenuation of the injection molded sample behavior for a greater thickness (16dB at 9mm). Additionally, the RL behavior of the parts with different infill patterns and thicknesses was studied. These results indicated that the MEX process might be a promising way to promote the reflection loss (RL) behavior of conductive materials that, in bulk, would not promote such a good response. The best RL performance found was -18 dB and 1.4GHz bandwidth for the 50wt% hexagonal infill pattern with an extra layer in the middle of the body sample.