|
چکیده
|
Despite the recent advances in the field of polymeric electromagnetic interference (EMI) shields, attenuating the EMwaves with an absorption-dominant mechanism is still an arduous challenge. Herein, flexible multilayer polyvinylidenefluoride (PVDF) films containing a small amount of reduced graphene oxide (rGO) and Zn0.5Ni0.5Fe2O4 (ZnNiFe)magnetic nanoparticles were designed for the fabrication of EMI absorbers. The nanofillers were synthesized and fullycharacterized with a wide range of characterization techniques, including VSM, FTIR, XRD, SEM and EDX. Results showthat the total EMI shielding effectiveness (SE) of the nanocomposites at the X-band frequency range increases from23dB to 28dB, and the shielding by reflection decreases from 6.5dB to 0.5dB as the number of the layers increasesfrom 2 to 9 at a constant thickness and loading of fillers. More importantly, our 9-layer sample showed an absorptioncoefficient of 0.91, which can be translated to absorption of more than 91% of the incident wave. To the best of ourknowledge, this is the highest ever reported absorbance for an EMI shield. The main reasons for the observed superiorEMI shielding performance of the 9-layer structure are: 1) multiple-reflection inside the shield due to the presence ofnumerous layers and 2) excellent magnetic properties of ZnNiFe nanoparticles, leading to enhanced magnetic loss,including normal resonance and eddy current losses in the specimens.
|