Effect of fabrication method on the structure and electromagnetic response of carbon nanotube/polystyrene composites in low-frequency and Ka bands

Casting, forge-rolling, and stretching methods have been used for preparation of polystyrene composites with 0.25 wt.% loading of multiwall carbon nanotubes (MWCNTs). Electromagnetic properties of the composites were studied using impedance spectroscopy and microwave probing in the K-a band. Analysis of impedance spectra revealed capacitive behavior of the forge-rolled composite and charge tunneling through a polystyrene layer separating the nanotubes in two other composite samples. The stretched composite demonstrated anisotropy of microwave response due to predominant orientation of nanotubes along deformation direction. The near-isotropic shielding efficiency of the forge-rolled composite was attributed to strong fragmentation of MWCNTs under applied shear forces. (C) 2014 Elsevier Ltd. All rights reserved.