Electromagnetic interference shielding effectiveness and microwave absorption properties of thermoplastic polyurethane/montmorillonite‐polypyrrole nanocomposites

Abstract

In this work, thermoplastic polyurethane-filled montmorillonite-polypyrrole (TPU/Mt-PPy) was prepared through melt mixing process for using in electromagnetic shielding applications. The effect of conducting filler content and type, sample thickness, and X-band frequency range on the electromagnetic interference shielding effectiveness (EMI SE) and EMI attenuation mechanism was investigated. A comparative study of electrical and microwave absorption properties of TPU/Mt-PPy nanocomposites and TPU/PPy blends was also reported. The total EMI SE average and electrical conductivity of all Mt-PPy.Cl or Mt-PPy.DBSA nanocomposites are higher than those found for TPU/PPy.Cl and TPU/PPy.DBSA blends. This behavior was attributed to the higher aspect ratio and better dispersion of the nanostructured Mt-PPy when compared with neat PPy. Moreover, the presence of Mt-PPy into TPU matrix increases absorption loss (SE A ) mechanism, contributing to increase EMI SE. The total EMI SE values of nanocomposites containing 30 wt% of Mt-PPy.DBSA with 2 and 5 mm thickness were approximately 16.6 and approximately 36.5 dB, respectively, corresponding to the total EMI of 98% (75% by absorption) and 99.9% (88% by absorption). These results highlight that the nanocomposites studied are promising materials for electromagnetic shielding applications. KEYWORDS montmorillonite, polypyrrole, shielding effectiveness, thermoplastic polyurethane 1 | INTRODUCTION Electromagnetic interference (EMI) has become a technical problem in the modern world because of the rapid proliferation of electronic and telecommunication systems, which emit electromagnetic radiation and may perturb the performance of electronic devices. To prevent EMI and increase the device efficiency and lifetime, many studies have been focused in producing electromagnetic radiation shielding or absorbing materials. In this context, electrically conducting polymer composites composed of intrinsically conducting polymer (ICP), such as polypyrrole (PPy) and polyaniline (PAni), dispersed in an insulating polymer matrix have attracted much interest for EMI shielding applications. 1-12 The scientific and technological interest for producing these materials is due to their lightweight, corrosion resistance, design flexibility, good processability, physical properties of polymeric materials, high electromagnetic interference shielding effectiveness (EMI SE), and good microwave absorption properties. 3,13-22 For many applications, the EMI SE value of 15 to 30 dB is considered satisfactory and corresponds to 99.9% attenuation of the EMI radiation. 13,23 Electromagnetic interference shielding effectiveness is influenced by 3 mechanisms: reflection (SE R ), absorption (SE A ), and multiple reflections (SE M ) of the electromagnetic waves. The attenuation of EMI by absorption has been preferred instead of reflection because of the increase demand of microwave absorbing materials. 24,25 Usually, microwave absorbing materials must display an electrical conductivity in the range of 10 −4 and 10 −1 S/...

Synergistic effect of double percolated co‐supportive MWCNT‐CB conductive network for high‐performance EMI shielding application

“…The extensive growth in the electronic industry and telecommunication systems in the recent past has made electromagnetic interference (EMI) a major concern . EMI is defined as the radiated or conducted electromagnetic radiations from an electronic device under its operation that can interfere in the proper functioning of neighboring electronic circuits and is considered as a new form of environmental pollution that can cause radiative damage to living beings .…”

Comparative Study of the Structure and Properties of Poly(Vinylidene Fluoride)/Montmorillonite-Polypyrrole Nanocomposites Prepared by Electrospinning and Solution Casting

“…There is a strong scientific and technological interest for producing conductive polymer composites (CPC's) due to the wide design flexibility and properties that can be obtained by combining different materials. Moreover, CPC's can display both the advantages of organic polymers, such as lightweight, flexible and easily moldable, and functionality of conductive additives, especially the electrical conductivity (Kim et al, 2003;Das et al, 2009;Lakshmi et al, 2009;Pirvu et al, 2011;Qin and Brosseau, 2012;Yan et al, 2012;Luzio et al, 2014;Merlini et al, 2017;Ramoa et al, 2018;Ram et al, 2019).…”

“…Intrinsically conducting polymers (ICP's), such as polypyrrole (PPy) and polyaniline (PANI), have been used as conductive filler to produce CPC's (Moučka et al, 2011;Jin et al, 2016;Merlini et al, 2017;Ramoa et al, 2018). Considerable efforts have been made in order to improve the dispersion of ICP's into the matrix and to reduce the amount of the filler necessary to achieve high values of electrical conductivity.…”

“…Considerable efforts have been made in order to improve the dispersion of ICP's into the matrix and to reduce the amount of the filler necessary to achieve high values of electrical conductivity. Works in literature have reported that the synthesis of PPy into layered inorganic host material, such as, montmorillonite (Mt), results in nanostructured conductive filler of Mt/PPy, with an intercalative or exfoliated structure, large surface area, and high electrical conductivity (Moučka et al, 2011;Jin et al, 2016;Merlini et al, 2017;Ramoa et al, 2018). The chemical in situ polymerization has been the most studied method for the production of Mt/PPy nanostructured conductive filler.…”

“…Moreover, the anionic surfactants (as DBSA) promoted the intercalation and partial exfoliation of the clay. In this context, the use of nanostructured conductive filler based on Mt-PPy.DBSA can be a strategy to improve the filler dispersion and the electrical conductivity of CPCs, when compared to neat PPy (Ramoa et al, 2018).…”