Cyanate ester filled with graphene nanosheets and multi-walled carbon nanotubes as a microwave absorber

Microwave absorbing composites with cyanate ester (CE) as matrix and both graphene nanosheets (GNSs) and multi-walled carbon nanotubes (MWCNTs) as absorbers were prepared, and their microwave absorbing properties were investigated in the frequency range of 2-18 GHz. The microstructures of the composites show a uniform dispersion of the GNSs and MWCNTs in the matrix. The complex permittivity of the composites increase with increasing fillers content. As microwave absorbing materials, the GNSs/MWCNTs/CE composites possess excellent absorption properties. Reflection loss values exceeding-5 dB (more than 70 % absorption) can be obtained in the frequency range of 9.12-14.15GHz with the count of 1.5 wt.% GNSs and 0.5 wt.% MWCNTs. Especially, a minimum reflection loss value of 32.4 dB was obtained at 11.2 GHz for the composite thickness of 2 mm. The enhanced microwave absorbing properties were also explained based on the structures of the composites. The mechanical properties of the composites were investigated in detail. It is observed that GNSs/MWCNTs reinforced CE composites demonstrated improved mechanical properties than that of CE matrix, which make them suitable for use in aerospace applications and radar absorbing material (RAM).