A new low-density hydrogel-based matrix with hollow microsphere structure for weight reduction of microwave absorbing composites

Abstract

A new low-density hydrogel-based composites matrix, super light clay (SLC), with a low density of 0.24 g/cm3, was prepared by mixing the hydrogel and hollow glass microspheres. The swelling-adsorption effect of hydrogel was used to adsorb carbonyl iron powder (CIP) on the surface of hollow microspheres. Benefitting from the existence of microporous structure and surface adsorption, the electromagnetic absorption performance of the obtained SLC/CIP composite microwave absorbing materials (MAMs) were greatly boosted. The results show that the composite filled with 11 vol% of the CIP had a minimum reflection loss (RL) of −45.3 dB and an effective absorption bandwidth (EAB, with a RL of less than −10 dB) of 4.81 GHz. In addition, the swelling-adsorption mechanism of the hydrogel-based SLC matrix and the high-frequency electromagnetic wave attenuation mechanisms have been also discussed. The environmentally friendly low-density matrix is of great significance for weight reduction of MAMs.