Isotactic polypropylene/carbon nanotube composites prepared by latex technology: Electrical conductivity study

High electromagnetic interference shielding of poly(ether-sulfone)/multi-walled carbon nanotube nanocomposites fabricated by an eco-friendly route

High-performance polymer matrix nanocomposites based on poly(ether-sulfone) (PES) matrix reinforced with multi-walled carbon nanotubes (MWCNTs) were fabricated using planetary ball mill followed by hot pressing. Their electrical properties and the electromagnetic interference shielding effectiveness (EMI-SE) were investigated and discussed. A percolation threshold of about 0.65 vol% MWCNT was obtained. The electrical conductivity was increased by more than ten orders of magnitude at the percolation threshold and to approximately 0.01 S cm^-1 at 6.67 vol% (or 10 wt%) MWCNT. This is a significant improvement. The highest EMI-SE of about 29-30 dB (both in the X-band and K_u-band) was obtained for the 6.67 vol% MWCNT filled nanocomposites with a thickness of 0.9 mm. The specific EMI-SE of these nanocomposites were found to be higher than the literature values. The thermal stability and the char yield (measured at 900 °C) of the nanocomposites were found to be more than 470 °C and 40.6%, respectively.

Factors that Affect Network Formation in Carbon Nanotube Composites and their Resultant Electrical Properties

This review paper explores the formation of carbon nanotube (CNT) polymer composites as a function of material and processing parameters. The effect of different polymer systems, increasing multiwall CNT content, modification of CNTs, processing conditions, and aspect ratio are discussed in detail for multi-walled carbon nanotubes (MWCNT) composites along with some examples for SWCNT composites. All of these factors influence the microstructure and how the network of CNTs forms within it. Often, researchers choose to modify the CNTs to aid in their distribution; however, this may result in a reduction or increase in conductivity depending on many factors. The electrical properties are directly affected by changes in the CNT network and how the material has been processed. As soon as the network forms, percolation occurs and the conductivity increases. In order to understand how to control the properties of CNT composites, all material characteristics and processing conditions must be taken into account.