Fabrication and Investigation of the Microwave Absorption of Nonwovens Modified by Carbon Nanotubes and Graphene Flakes

This study aims to investigate the influences of carbon nanotubes (CNTs) and graphene flakes (GFs) on the microwave absorption performance of nonwovens. Nonwovens were modified with CNTs and GFs through an impregnation method, creating a series of absorption samples with different carbon nanomaterial contents. Then the absorption performance of the samples was tested on both sides in the X-band (8.2 similar to 12.4 GHz) and the Ku-band (12 similar to 18 GHz) using the arch method. The experimental results showed that the absorption performance of GF-impregnated nonwovens was superior to that of CNT-impregnated nonwovens, and the overall absorption performance in the Ku-band was better than in the X-band. At a CNT content of 5 wt.%, the reflection loss of the impregnated nonwovens on the backside reached a minimum of -14.06 dB and remained below -10 dB in the 17.42 similar to 17.88 GHz frequency range. The sample fabricated with 4 wt.% GFs in the impregnation solution exhibited the best absorption performance, with minimum reflection losses of -15.33 dB and -33.18 GHz in the X-band and Ku-band, respectively. When the GFs were at 3 wt.%, the absorption bandwidth below 10 dB reached 4.16 GHz. In contrast to CNT-impregnated nonwovens, the frontside of GF-impregnated nonwovens demonstrated better absorption performance in the Ku-band. The results of this work provide experimental data support for the fabrication and application of microwave absorption materials.