Performance Simulation and Fused Filament Fabrication Modeling of the Wave-Absorbing Structure of Conductive Multi-Walled Carbon Nanotube/Polyamide 12 Composite

Fused filament fabrication (FFF) is a reliable method for fabricating structured electromagnetic wave (EMW) absorbers from absorbing materials. In this study, polymer-matrix composites were prepared using polyamide 12 (PA12) which was recovered from selective laser sintering (SLS) as the substrate and multi-walled carbon nanotubes (MWCNT) as the filler. The CST software is used for simulation calculation and study of electromagnetic wave absorption characteristics of composite materials. After that, based on the obtained parameters and results, modeling was carried out, and finally, EMW absorbers with various microstructures were fabricated by FFF. For the honeycomb structure sample, when the side length is 5 mm and the height is 2 mm, the minimum return loss (RL) of the composite at 15.81 GHz is −14.69 dB, and the maximum effective absorption bandwidth is 1.93 GHz. These values are consistent with the simulation results. The pyramid structure has better absorbing performance than plate structure and honeycomb structure. According to simulation calculations, the pyramid structure shows the best performance at an angle of 28°. The absorption performance of the printed pyramid structure sections exceeded the simulated values, with effective absorption bandwidth (EAB) reaching all frequencies from 2 to 18 GHz, with a minimum return loss of −47.22 dB at 8.24 GHz.