Combined effect of graphene oxide and MWCNTs on microwave absorbing performance of epoxy composites

Currently, carbon nanotube (CNT) -based composites have been considered as microwave absorbers because of the fascinating properties of CNTs. In this work, multi-walled CNTs (MWCNTs) and graphene oxide (GO) -based epoxy composites (i.e. MWCNT/EPr and GO-MWCNT/EPr), with sample thickness of 2mm, were prepared to study microwave absorbing properties in the frequency band of 8-18GHz. Uniform dispersion of MWCNTs in the organic solvent and polymer matrix was achieved by preparation of GO. The test for electromagnetic parameters, i.e. complex permittivity and the permeability of the samples, was carried out with vector network analyzer (VNA) using reflection-transmission waveguides. Results showed that GO-MWCNT/EPr composites have better absorption capability than MWCNT/EPr composites. The improved reflection loss for the composites with 0.4wt% and 0.6wt% of GO (out of total filler loading 6wt%) were -14.32dB and -14.29dB, respectively. The improvement in reflection loss and absorption bandwidth for GO-MWCNTs composites suggested that MA features are synergistically effected by GO and MWCNTs. Further skin depth and shielding effectiveness terms are studied to observe overall mechanism of electromagnetic (EM) shielding which showed that multiple reflections also play a role in EM shielding.