Dielectric Relaxation Spectroscopy and Synergy Effects in Epoxy/MWCNT/Ni@C Composites
Open Access
- 23 February 2021
- journal article
- research article
- Published by MDPI AG in Nanomaterials
- Vol. 11 (2), 555
- https://doi.org/10.3390/nano11020555
Abstract
The dielectric/electric properties of the Ni@C (carbon-coated Ni)/epoxy composites and Ni@C/MWCNTs (multi-walled carbon nanotubes)/epoxy composites loaded with fixed MWCNTs amount just below the percolation threshold (0.09 vol.%) and Ni@C at different concentrations up to 1 vol.% were investigated in broad frequency (20 Hz–40 GHz) and temperature (30 K–500 K) regions. In composites with the only Ni@C nanoparticles, the electrical percolation threshold was determined between 10 and 15 vol.%. Above the percolation threshold the dielectric permittivity (ε’) and the electrical conductivity (σ) of the composites loaded with Ni@C only are high enough, i.e., ε’ = 105 and σ = 0.6 S/m at 100 Hz for composites with 30 vol.% Ni@C, to be used for electromagnetic shielding applications. The annealing to 500 K was proved to be an effective and simple tool to decrease the percolation threshold in epoxy/Ni@C composites. For hybrid composites series an optimal concentration of Ni@C (0.2 vol.%) was determined, leading to the conductivity absolute values several orders of magnitude higher than that of a composite filled with MWCNTs only. The synergy effects of using both fillers have been discussed. Below room temperature the electrical transport is mainly governed by epoxy resin compression in all composites, while the electron tunnelling was observed only in hybrid composites below 200 K. At higher temperatures (above 400 K), in addition to the nanoparticles redistribution effects, the electrical conductivity of epoxy resin makes a significant contribution to the total composite conductivity. The dielectric relaxation spectroscopy allows estimating the nanoparticles distributions in polymer matrix and could be used as the non-destructive and fast alternate to microscopy techniques for general polymer composite fabrication control.This publication has 33 references indexed in Scilit:
- Frequency and density dependencies of the electromagnetic parameters of carbon nanotube and graphene nanoplatelet based composites in the microwave and terahertz rangesMaterials Research Express, 2019
- Electromagnetic Parameters of Composite Materials Based on Polyethylene and Multi-Walled Carbon Nanotubes Modified by Iron Oxide NanoparticlesRussian Journal of Applied Chemistry, 2018
- Synergy effects in the electrical conductivity behavior of onion-like carbon and multiwalled carbon nanotubes compositesPhysica Status Solidi (b), 2015
- Synergistic effect of carbon nanotubes and carbon black on electrical conductivity of PA6/ABS blendComposites Science and Technology, 2013
- A REVIEW OF THE APPLICATIONS OF NANOCARBON POLYMER COMPOSITESNano, 2011
- Synergistic effects in network formation and electrical properties of hybrid epoxy nanocomposites containing multi-wall carbon nanotubes and carbon blackJournal of Materials Science, 2009
- The long and short of carbon nanotube toxicityNature Biotechnology, 2008
- Carbon based conductive polymer compositesJournal of Materials Science, 2007
- Dielectric spectroscopy on melt processed polycarbonate—multiwalled carbon nanotube compositesPolymer, 2003
- Percolation and ConductionReviews of Modern Physics, 1973