Ultra-porous and lightweight microwave absorber based on epoxy foam loaded with long carbon fibers

A simple methodology to fabricate ultra-porous and lightweight epoxy foam composites loaded with carbon fibers is presented. These materials are proposed for microwave absorbing application. The elaborated composite density can be controlled via proper proportioning of carbon fiber/solvent/surfactant/epoxy components constituting the absorber composites. The influence of the weight percentage of these different components, on the composite structure, is studied. The density of the composites can be reduced to 0.05g.cm(-3) while the density of the neat epoxy foam is about 0.12g.cm(-3). Dielectric characterization of composites elaborated with low weight percentages of carbon fibers (from 0.0125 wt.% to 0.075 wt.%) is conducted using free space method. The simulation of a multilayer absorber is conducted and predicts a promising absorption performance (reflection coefficient <-10 dB) for the wide studied frequency band; this result was confirmed by the measurement of a multilayer absorber prototype. Finally, these performances are compared to commercial absorber materials having same dimensions.

Automated summary

This study introduces a simple method to fabricate ultra-porous and lightweight epoxy foam composites loaded with carbon fibers for microwave absorbing applications. The composite density can be controlled by adjusting the proportion of carbon fiber/solvent/surfactant/epoxy components, resulting in a significant reduction in density compared to neat epoxy foam. The dielectric characterization and simulation of multilayer absorbers demonstrate promising absorption performance across a wide frequency band, which is confirmed by experimental measurements.