Abstract
Polymer composites containing nanocarbon fillers are under intensive investigation worldwide due to their remarkable electromagnetic properties distinguished not only by components as such, but the distribution and interaction of the fillers inside the polymer matrix. The theory herein reveals that a particular effect connected with the homogeneity of a composite manifests itself in the terahertz range. Transmission time-domain terahertz spectroscopy was applied to the investigation of nanocomposites obtained by co-extrusion of PLA polymer with additions of graphene nanoplatelets and multi-walled carbon nanotubes. The THz peak of permittivity’s imaginary part predicted by the applied model was experimentally shown for GNP-containing composites both below and above the percolation threshold. The physical nature of the peak was explained by the impact on filler particles excluded from the percolation network due to the peculiarities of filler distribution. Terahertz spectroscopy as a versatile instrument of filler distribution diagnostics is discussed.
Highlights
Functional materials based on micro- and nanocarbon structures are of great interest for electromagnetic (EM) applications alongside composites [1,2,3,4,5,6,7] and structures [8,9,10,11,12] on their basis
The typical aspect ratio (AR) for graphene nanoplatelets lies in the range of 100–1000
The impact of nanofiller particles excluded from the percolation network was demonstrated by means of transmission time-domain terahertz spectroscopy
Summary
Functional materials based on micro- and nanocarbon structures (single and multi-walled nanotubes, graphene flakes, carbon dots, nanohorns, etc.) are of great interest for electromagnetic (EM) applications alongside composites [1,2,3,4,5,6,7] and structures [8,9,10,11,12] on their basis. Possessing the highest possible aspect ratio among all nanocarbon fillers, nanotubes are the first candidate to create a conductive network inside a composite, i.e., reach the electric percolation threshold at the smallest possible concentration [2,21,22,23]. Another widely-used nanocarbon filler, namely, Polymers 2020, 12, 3037; doi:10.3390/polym12123037 www.mdpi.com/journal/polymers. Multi-filler composites containing different types of fillers (including non-carbon) tend to form heterogeneous percolation networks [30,31,32]. The possibilities to tune the frequency dispersion of permittivity in THz range by variation of filler contents in composites based on GNP, MWCNT and their mixtures are discussed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
