Designing of Nano Composites of Conducting Polymers for EMI Shielding

Dhawan, S. K.; Ohlan, Anil; Singh, Kuldeep

doi:10.5772/14752

Cited by 20 publications

(25 citation statements)

References 87 publications

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“…The observed trends and measured SE T for xGNP/PLA composites resemble those of xGNP/PBAT composites with similar complex electromagnetic parameters [35]. For M15 and M25 composites, SE T decreases with increasing frequency, which is a phenomenon that has been observed in other conductive polymer composites [36,37]. C750 and PLA exhibited minimal frequency dependence for SE T in this frequency range.…”

Section: Resultsmentioning

confidence: 53%

Comparison of Experimental and Modeled EMI Shielding Properties of Periodic Porous xGNP/PLA Composites

2019

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Microwave absorbing materials, particularly ones that can achieve high electromagnetic interference (EMI) absorption while minimizing weight and thickness are in high demand for many applications. Herein we present an approach that relies on the introduction of periodically placed air-filled pores into polymer composites in order to reduce material requirements and maximize microwave absorption. In this study, graphene nano platelet (xGNP)/poly-lactic acid (PLA) composites with different aspect ratio fillers were characterized and their complex electromagnetic properties were extracted. Using these materials, we fabricated non-perfect electrical conductor (PEC) backed, porous composites and explored the effect of filler aspect ratio and pore geometry on EMI shielding properties. Furthermore, we developed and experimentally verified a computational model that allows for rigorous, high-throughput optimization of absorbers with periodic porous geometries. Finally, we extend the modeling approach to explore the effect of pore addition on PEC-backed composites. Our composite structures demonstrated decreased fractions of reflected power and increased fractions of absorbed power over the majority of the X Band due to the addition of periodically arranged cylindrical pores. Furthermore, we showed that for xGNP/PLA composite material, reflection loss can be increased by as much as 13 dB through the addition of spherical pores. The ability to adjust shielding properties through the fabrication of polymer composites with periodically arranged pores opens new strategies for the modeling and development of new microwave absorption materials.

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Section: Resultsmentioning

confidence: 53%

Comparison of Experimental and Modeled EMI Shielding Properties of Periodic Porous xGNP/PLA Composites

2019

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“…Therefore, the total SE (SET) can be expressed as follows [ 41 , 42 ]: SE T = SE A + SE R + SE M where SE A , SE R , and SE M are the shielding effectivenesses by absorption, reflection, and multiple reflections, respectively, which are defined as [ 42 ]: SE T = 10log(P i /P t ) SE A = 20loge t/ σ SE R = 39.5 + 10log(σ/2fπμ) SE M = 20log(1 − e −2t/δ ) where Pi, Pt, σ, f, μ, and δ are the incident and transmitted power, conductivity, frequency, permeability, and skin depth, respectively. Since the shield thickness of the developed foams is greater than skin depth (defined as the distance from the surface of the shield where the EM energy has dropped to 1/e of its initial value at the surface) [ 42 ], the effect of multiple reflections can be overlooked [ 43 , 44 ]. The three SE parameters were calculated ( Figure 6 ) for our tested samples with the thickness of 9 mm over the X-band frequencies [ 41 ].…”

Section: Resultsmentioning

confidence: 99%

Preparation and Characterization of Highly Elastic Foams with Enhanced Electromagnetic Wave Absorption Based On Ethylene-Propylene-Diene-Monomer Rubber Filled with Barium Titanate/Multiwall Carbon Nanotube Hybrid

et al. 2020

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Hybrid ethylene-propylene-diene-monomer (EPDM) nanocomposite foams were produced via compression molding with enhanced electromagnetic wave absorption efficiency. The hybrid filler, consisting of 20 phr ferroelectric barium titanate (BT) and various loading fractions of multi-wall carbon nanotubes (MWCNTs), synergistically increased the electromagnetic (EM) wave absorption characteristics of the EPDM foam. Accordingly, while the EPDM foam filled with 20 phr BT was transparent to the EM wave within the frequency range of 8.2–12.4 GHz (X-band), the hybrid EPDM nanocomposite foam loaded with 20 phr BT and 10 phr MWCNTs presented a total shielding effectiveness (SE) of ~22.3 dB compared to ~16.0 dB of the MWCNTs (10 phr). This synergistic effect is suggested to be due to the segregation of MWCNT networks within the cellular structure of EPDM, resulting in enhanced electrical conductivity, and also high dielectric permittivity of the foam imparted by the BT particles. Moreover, the total SE of the BT/MWCNTs loaded foam samples remained almost unchanged when subjected to repeated bending due to the elastic recovery behavior of the crosslinked EPDM foamed nanocomposites.

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“…These variations might lead to the flickering in geometrical orientation such that the plane is parallel or perpendicular to the electromagnetic field and hence suppressing or enhancing the electrical conductivity, respectively [11]. It is important to mention that the conductivity shifts depicted in Figure 2 had covered the range between 10 2 -10 −6 S/cm, which are corresponding with that of semiconductors [13].…”

Section: Conductivitymentioning

confidence: 98%

Frequency Dependence of Atomic Diffusivity and Electrical Properties of Gum Arabic/Graphite Composite

Adham¹,

El-Khair²,

Siddig³

2015

MSCE

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In this study, Gum Arabic (GA)/Graphite (Gr) composite material was prepared using solid state reaction method. The FTIR peaks obtained were referred to the binding of Gr with the active groups in GA, such as NH2, COOH, CHO, CNC (alkyl amine) and C=CH (aromatic monosubstitution). Atomic diffusivity of Gr in GA was calculated using simple model and was found to varied randomly. This randomness might be due to the attachment of Gr with different active groups of GA. The addition of Gr results in improvement of the conductivity of GA to a far extend as it reaches the semiconductor range. The random variation in conductivities of the samples can be attributed to the effect of high frequency range, where the effect of phonon-electron is dominant. The samples subjected to the impedance spectroscopy (IS) for second and third time were acquired different diffusivities as well as conductivities. Such variations might indicate that IS was a processing technique similar to thermal treatment since it boosted the Gr atomic diffusion.

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Designing of Nano Composites of Conducting Polymers for EMI Shielding

Cited by 20 publications

References 87 publications

Comparison of Experimental and Modeled EMI Shielding Properties of Periodic Porous xGNP/PLA Composites

Comparison of Experimental and Modeled EMI Shielding Properties of Periodic Porous xGNP/PLA Composites

Preparation and Characterization of Highly Elastic Foams with Enhanced Electromagnetic Wave Absorption Based On Ethylene-Propylene-Diene-Monomer Rubber Filled with Barium Titanate/Multiwall Carbon Nanotube Hybrid

Frequency Dependence of Atomic Diffusivity and Electrical Properties of Gum Arabic/Graphite Composite

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