Polyethylene Composites with Segregated Carbon Nanotubes Network: Low Frequency Plasmons and High Electromagnetic Interference Shielding Efficiency

Abstract

Polyethylene (PE) based composites with segregated carbon nanotubes (CNTs) network was successfully prepared by hot compressing of a mechanical mixture of PE and CNT powders. Through comparison with a composite comprising randomly distributed carbon nanotubes of the same concentration, we prove that namely the segregated CNT network is responsible for the excellent electrical properties, i.e., 10−1 S/m at 0.5−1% and 10 S/m at 6−12% of CNT. The investigation of the complex impedance in the frequency range 1 kHz−2 MHz shows that the sign of real part of the dielectric permittivity ε r ′ changes from positive to negative in electrically percolated composites indicating metal-like behavior of CNT segregated network. The obtained negative permittivity and AC conductivity behavior versus frequency for high CNT content (3−12%) are described by the Drude model. At the same time, in contrast to reflective metals, high electromagnetic shielding efficiency of fabricated PE composites in the frequency range 40−60 GHz, i.e., close to 100% at 1 mm thick sample, was due to absorption coursed by multiple reflection on every PE-CNT segregated network interface followed by electromagnetic radiation absorbed in each isolated PE granule surrounded by conductive CNT shells.

Keywords

• carbon nanotube
• polyethylene
• segregated composite
• complex impedance
• electromagnetic shielding