Influence of conductive network structure on the EMI shielding and electrical percolation of carbon nanotube/polymer nanocomposites

• Conductive composites have applications in the electronics and energy sectors.
• Segregated network was prepared by placing CNT at the external surface of UHMWPE.
• Only 0.054 vol% CNT was required to electrically percolate the system.
• EMI SE of 50 dB was reported for a 1.0 mm plate made of 10 wt% CNT nanocomposite.
• The thick and segregated CNT network enhanced the EMI shielding by absorption.

Conductive polymer nanocomposites (CPNC) are promising materials for electromagnetic interference shielding (EMI) applications. However, the relatively high cost of high aspect ratio nanofillers hinders the wide commercial use of these materials. Promoting the competitiveness of CPNCs requires formulation nanocomposites with the desired EMI capabilities at the lowest possible nanofiller loading. This requires better understanding for relation between the microstructure and EMI attenuation mechanisms, which is the objective of this work. Herein, CNPCs with segregated conductive network were prepared by placing carbon nanotube (CNT) particles at the external surface of ultrahigh molecular weight polyethylene (UHMWPE) powder by wet mixing. The microstructure, electrical and EMI shielding properties of the nanocomposites after compression molding were investigated. The EMI SE was found to increase with CNT content. An EMI SE of 50 dB was reported for a 1.0 mm thick plate made of 10 wt% CNT/UHMWPE nanocomposite. This nanostructured material is suitable for many applications in the computer and electronics industries. Compared to CNT/polymer nanocomposite of fine and well-dispersed CNT microstructure, the unique structure of the CNT/UHMWPE characterized by thick and segregated CNT network was found to enhance the EMI shielding by absorption and reduce the reflection of the EMI.