Effect of processing methods on electrical percolation and electromagnetic shielding of PC/MWCNTs nanocomposites

Nanocomposites of polycarbonate (PC)/multiwalled carbon nanotubes (MWCNTs) containing 0.5–3 wt% of MWCNTs were prepared via two methods of melt mixing and solution mixing. The effect of CNT content and processing methods on electrical and electromagnetic properties of nanocomposite samples were investigated. TEM microphotographs revealed that the PC/MWCNT composites prepared by the solution method, have better dispersion and distribution of CNTs in the PC matrix. Electrical measurements indicated an electrical percolation threshold of less than 1 wt% of CNTs for this system. Also, it was found that PC/MWCNT composites prepared by the solution method, exhibit higher electrical conductivity and lower electrical percolation threshold. The electromagnetic interference shielding effectiveness (EMI SE) measurements in the X‐band (8.2–12.4 GHz) indicated that EMI SE is increased by increasing the amount of CNTs in the samples, and also the thickness of specimens. In addition, the results showed that the composites prepared by the solution method, have higher SE values. Finally, in order to reach an acceptable value for commercial applications of EMI shielding materials (20 dB), thicker samples were produced and it was found that the 3.5 mm thick samples containing 2 wt% CNTs, have a 19.6 dB shielding effectiveness. POLYM. COMPOS., 38:E269–E276, 2017. © 2016 Society of Plastics Engineers