TY - JOUR
T1 - Electromagnetic characteristics of systems of prolate and oblate ellipsoids
AU - Karimi, Pouyan
AU - Amiri-Hezaveh, Amirhossein
AU - Ostoja-Starzewski, Martin
AU - Jin, Jian Ming
N1 - Funding Information:
We would like to thank the Private Sector Program and the Blue Waters sustained-petascale computing project at the National Center for Supercomputing Applications (NCSA), which was supported by the National Science Foundation (Award Nos. OCI-0725070 and ACI-1238993) and the state of Illinois. The authors gratefully acknowledge the use of the Taub cluster resources provided under the Computer Science and Engineering (CSE) program at the University of Illinois. This work was financially supported by the NSF Center for Novel High Voltage/Temperature Materials and Structures [NSF I/UCRC (IIP-1362146)].
Publisher Copyright:
© 2017 Author(s).
PY - 2017/11/14
Y1 - 2017/11/14
N2 - The present study suggests a novel model for simulating electromagnetic characteristics of spheroidal nanofillers. The electromagnetic interference shielding efficiency of prolate and oblate ellipsoids in the X-band frequency range is studied. Different multilayered nanocomposite configurations incorporating carbon nanotubes, graphene nanoplatelets, and carbon blacks are fabricated and tested. The best performance for a specific thickness is observed for the multilayered composite with a gradual increase in the thickness and electrical conductivity of layers. The simulation results based on the proposed model are shown to be in good agreement with the experimental data. The effect of filler alignment on shielding efficiency is also studied by using the nematic order parameter. The ability of a nanocomposite to shield the incident power is found to decrease by increasing alignment especially for high volume fractions of prolate fillers. The interaction of the electromagnetic wave and the fillers is mainly affected by the polarization of the electric field; when the electric field is perpendicular to the equatorial axis of a spheroid, the interaction is significantly reduced and results in a lower shielding efficiency. Apart from the filler alignment, size polydispersity is found to have a significant effect on reflected and transmitted powers. It is demonstrated that the nanofillers with a higher aspect ratio mainly contribute to the shielding performance. The results are of interest in both shielding structures and microwave absorbing materials.
AB - The present study suggests a novel model for simulating electromagnetic characteristics of spheroidal nanofillers. The electromagnetic interference shielding efficiency of prolate and oblate ellipsoids in the X-band frequency range is studied. Different multilayered nanocomposite configurations incorporating carbon nanotubes, graphene nanoplatelets, and carbon blacks are fabricated and tested. The best performance for a specific thickness is observed for the multilayered composite with a gradual increase in the thickness and electrical conductivity of layers. The simulation results based on the proposed model are shown to be in good agreement with the experimental data. The effect of filler alignment on shielding efficiency is also studied by using the nematic order parameter. The ability of a nanocomposite to shield the incident power is found to decrease by increasing alignment especially for high volume fractions of prolate fillers. The interaction of the electromagnetic wave and the fillers is mainly affected by the polarization of the electric field; when the electric field is perpendicular to the equatorial axis of a spheroid, the interaction is significantly reduced and results in a lower shielding efficiency. Apart from the filler alignment, size polydispersity is found to have a significant effect on reflected and transmitted powers. It is demonstrated that the nanofillers with a higher aspect ratio mainly contribute to the shielding performance. The results are of interest in both shielding structures and microwave absorbing materials.
UR - http://www.scopus.com/inward/record.url?scp=85033567550&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85033567550&partnerID=8YFLogxK
U2 - 10.1063/1.5000045
DO - 10.1063/1.5000045
M3 - Article
AN - SCOPUS:85033567550
SN - 0021-8979
VL - 122
JO - Journal of Applied Physics
JF - Journal of Applied Physics
IS - 18
M1 - 185101
ER -