Hybrid Nanocomposites With Organoclay and Carbon-Based Fillers for EMI Suppression

Abstract

The reinforcing role of clays in modern nanocomposites raises the question upon potential synergies with other fillers, in terms of their microwave properties and performance. To this effect, hybrid, multiphase composites are fabricated to comprise organomodified nanoclay (NC) and multiwalled carbon nanotubes (MWCNTs) or carbon black nanoparticles (CB) at varying concentrations in epoxy resin matrix (ER). The performed electromagnetic (EM) characterization in the 2-18-GHz band reveals that NC generally degrades the effective permittivity ε * eff of the NC/CB/epoxy composites, whereas for 2wt% NC a local ε * eff maximum is observed in the NC/MWCNT/epoxy system. This divergent impact of NC is attributed to different microstructural features affecting the dipolar dielectric polarization. Finally, the composites with high ε * eff contribute to the miniaturization of reflection reducing and shielding panels, since the respective return and transmission loss are found to be dominated by the destructive interference mechanism. For both topologies, the composite loaded with 2wt% NC and 0.5wt% MWCNT is evaluated as the most effective in attenuating the EM waves. Through the analysis of the microwave dielectric properties and the shielding mechanisms, the material design objectives emerge along with the potential of NC/carbon nanotubes composites for suppression of EM interference.

Nanoclay-based Polymer Nanocomposites for Electromagnetic Interference Shielding

“…With 5 wt. % fraction of polyaniline-clay nanocomposite prepared using 3-pentadecyl phenol 4-sulphonic acid (PANICN-PDPSA) and polyaniline-clay nanocomposite prepared using dodecyl benzene sulfonic acid (PANICN-DBSA) conductivity increased to 8.03 x 10 -3 S/m and 8.72 x 10 -3 S/m respectively, similar trends can be seen in papers [7,32]. SEM images shown in Figure 3 demonstrate the formation of interconnected conductive networks in the presence of nanoclay in such nanocomposites at a very low filler concentration and the desired value of electrical conductivity in the range of 10 -1 S/m is shown to be achieved with 5 wt.…”

X-band microwave absorbing characteristics of multicomponent composites with magnetodielectric fillers

“…carbon nanofibers CNFs, carbon nanotubes CNTs and multiwalled nanotubes MWCNT) with high dielectric losses, because of their electrical conduction or the orientational polarization losses, are considered as electric field absorbers [13][14][15][16]. On the contrary, ceramic materials usually possess low or moderate conductivity values, hence their microwave absorption capability basically stems from their dielectric polarization losses.…”

Υβριδικά Συστήματα Πολυμερικής Μήτρας Με Μικρο- Και Νανο- Πληρωτές Άνθρακα

“…Σχήμα 3.17 Σχηματικό διάγραμμα θεμελιωδών τοπολογιών ΕΜΙ προστασίας: (α) καταστολήςανακλάσεων και (β) ηλεκτρομαγνητικής θωράκισης[435] Εξαιτίας της εκτεταμένης έρευνας και του βιομηχανικού ενδιαφέροντος, αρκετές μελέτες έχουν επικεντρωθεί και σε υβριδικά/πολυφασικά νανοδιηλεκτρικά (nanodielectric) σύνθετα υλικά παρουσιάζοντας την συνέργεια μεταξύ νανοπηλών (nanoclays) και πληρωτών με βάση τον άνθρακα, από την άποψη της μορφολογίας, των διεπιφανειακών αλληλεπιδράσεων και της τελικής φυσικής τους συμπεριφοράς (ηλεκτρικής, θερμικής και μηχανικής)[436][437][438].…”