Pre-compliance testing of the shielding effectiveness of 3D printed multiwall carbon nanotube/ethylene-vinyl acetate copolymer composites in the 1 – 7 GHz range

Abstract

Copolymer composites with 1-, 3- and 5 % weight concentration of carbon nanotubes (CNT) with average diameters of 9.5mm were fabricated using three different printing orientations: 0°, alternative ± 45°, and alternative +0°/- 90°. Shielding effectiveness (SE) of samples of 100x100x1 mm was measured with near-field probes connected to a vector network analyser based on a pre-compliance procedure. Both electric- and magnetic-shielding properties could be investigated. Using a reference material of a recognised producer, we emphasized comparative shielding properties in the (1-7) GHz range. Low SE values were generally observed for all samples, not exceeding 12.5 dB, but they were dependent on both the printing direction and CNT wt%. The measurements indicate that frequencies larger than 7 GHz may show better shielding properties. Also, indications of the best combination between CNT concentration and printing direction were deducted.