Preparation And Electromagnetic Shielding Properties Of Graphene-magnetic Particles/Cyanate Ester Composites

The proliferation of various electronic devices in industrial and home environments has caused a great deal of electromagnetic interference(EMI),and shielding is an effective means to suppress EMI.Due to the current trend of slight development of electronic equipment,electromagnetic shielding materials have been demanded to be "higher,wider,and thinner",lightweight high-efficiency carbon materials have become a research hotspot as an excellent electromagnetic shielding material,and graphene is one of the best among them.However,the problem of impedance mismatch in graphene limits its application.In this paper,CE was used as substrate,GNSs as dielectric loss agent,magnetic particles CIP and RGO@NiFe2O4 as magnetic loss agent,so as to regulate the dielectric parameters of GNSs,to achieve the purpose of improving the impedance matching.The micro-level CIP was first used as magnetic loss agent and introduced into the GNSs/CE system to investigate the effect of CIP content on its electromagnetic properties and electromagnetic shielding properties.The results show that the GN5C10 composite exhibits excellent electromagnetic shielding effectiveness(?30dB)in the X-band(8.2-12GHz),peaking at 11.79GHz with 47.6dB,where the absorption loss accounts for about 92%of the shielding effectiveness.GNSs as dielectric element with a high conductivity cause a high dielectric loss of electromagnetic waves,and CIP as magnetic loss material with a high magnetic permeability can attenuate electromagnetic waves by eddy current and resonance.Subsequently,using GO as a carrier,RGO@NiFe2O4 nanomaterials were prepared by hydrothermal method.Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD)and other test results show that the NiFe2O4 particles were successfully loaded on the RGO surface.In addition,GO was also restored as RGO during the preparation process.Then,RGO@NiFe2O4 was introduced into the GNSs/CE system,the effect of RGO@NiFe2O4 content on the electrical conductivity and electromagnetic shielding performance of the composites were investigated.The results show that the addition of RGO@NiFe2O4 has a significant effect on the electromagnetic shielding performance on the basis of the small influence on the electrical conductivity of the composites.G5N15 composite has the highest electromagnetic shielding effectiveness up to 49.6dB,of which absorption loss is 43dB,accounting for 86.7%of the total shielding effectiveness.It is worth noting that after the addition of RGO@NiFe2O4,the reflection loss of the composite was basically unchanged,but the absorption loss increased significantly.This study lays a foundation for solving the impedance mismatch problem of graphene electromagnetic shielding materials.