Low content Ag-coated poly(acrylonitrile) microspheres and graphene for enhanced microwave absorption performance epoxy composites

Abstract

Silver nanoparticles was uniformly anchored on the surface of hollow poly(acrylonitrile) microspheres with a facile chemical method using hydrazine hydrate as reductant. Integrating these conducting hollow spheres (PANS@Ag) with chemical reduced graphene oxide (RGO) dispersed in epoxy resin, a lightweight microwave absorber was successfully prepared with enhanced microwave absorption performance. The chemical constitution and surface morphology of as-synthesized RGO and PANS@Ag powders were characterized by XRD, XPS, FE-SEM and SAED, while the electromagnetic properties of these different proportion PANS@Ag-RGO/EP samples were analyzed through vector network analyzer (VNA). The minimum reflection loss (RL) could reach up to −28.1 dB at 8.8 GHz with a layer thickness of 2 mm, and the corresponding effective absorption bandwidth (RL values less than −10 dB) was from 7.9 GHz to 9.8 GHz. However, the dosage of PANS@Ag and RGO was merely 3 wt% and 1 wt%, respectively. As the content of PANS@Ag powders decreased to 1 wt%, the PANS@Ag-RGO/EP samples still retained effective microwave absorption performance and the optimal RL was −14.7 dB. The density of as-prepared absorbers was in the range of 0.49 ∼ 0.87 g cm−3. The low content, low density and enhanced microwave absorption performance endow the hybrid composites with competitive application prospect in stealth technology field.