Nickel‐coated carbon fillers for polyurethane foam with improved microwave absorption performance: A comparative analysis

Abstract

AbstractIn this study, polyurethane foam (PUF) composites were prepared by incorporating different functional fillers, and morphological, rheological, dielectric, and microwave absorption properties of these composite samples were investigated. Graphite (G), nickel (Ni), nickel‐coated hybrid carbon (NiC), and iron II‐III oxide (Fe3O4) powders were used as functional fillers, while rigid polyurethane foam (PUF) with a 40 kg/m3 density and a closed‐cell structure was used as the carrier foam phase. Morphological analyses that were carried out by scanning electron microscopy showed that all fillers were dispersed between the cell walls. In dielectric characterization, the highest electrical permittivity values were obtained by incorporation of G, while the highest magnetic permeability values were obtained by incorporation of Fe3O4 at the same filler concentration. Furthermore, the PUF composites could be prepared using NiC at a higher filler concentration than the others due to the lower viscosity increasing effect of NiC. The highest microwave absorption performance was obtained in the NiC‐filled PUF composite at a filler concentration of 120 phr. The minimum reflection loss (RL) value of −45.2 dB at 10.62 GHz and an RL value lower than −10 dB in the entire X‐band region were obtained in the NiC‐filled PUF composite.Highlights Nickel‐coated carbon (NiC) filled polyurethane foam (PUF) was prepared. The absorption performance of NiC was compared to conventional filler. PUF composites containing NiC showed lower viscosity and processability. The highest absorption could be obtained by NiC compared to conventional fillers.