Effects of inclusion concentration on effective permittivity of shielding composites

2015 ◽  
Author(s):  
Yi Liao ◽  
Yuan Zhang ◽  
Yi Wang
Keyword(s):  
Effective Permittivity ◽  
Inclusion Concentration ◽  
Shielding Composites

scholarly journals Polymer‐based EMI shielding composites with 3D conductive networks: A mini‐review

SusMat ◽  
2021 ◽  
Author(s):  
Lei Wang ◽  
Zhonglei Ma ◽  
Yali Zhang ◽  
Lixin Chen ◽  
Dapeng Cao ◽  
...  
Keyword(s):  
Emi Shielding ◽  
Shielding Composites

Polymeric textile-based electromagnetic interference shielding materials, their synthesis, mechanism and applications – A review

2021 ◽  
pp. 152808372110370
Author(s):  
Faiza Safdar ◽  
Munir Ashraf ◽  
Amjed Javid ◽  
Kashif Iqbal
Keyword(s):  
Electromagnetic Interference ◽  
Hybrid Composites ◽  
Electronic Devices ◽  
High Tech ◽  
Emi Shielding ◽  
Materials Synthesis ◽  
Synthesis Mechanism ◽  
High Frequencies ◽  
Textile Materials ◽  
Shielding Composites

The rapid proliferation of electronic devices and their operation at high frequencies has raised the contamination of artificial electromagnetic radiations in the atmosphere to an unprecedented level that is responsible for catastrophe for ecology and electronic devices. Therefore, the lightweight and flexible electromagnetic interference (EMI) shielding materials are of vital importance for controlling the pollution generated by such high-frequency EM radiations for protecting ecology and human health as well as the other nearby devices. In this regard, polymeric textile-based shielding composites have been proved to be the best due to their unique properties such as lightweight, excellent flexibility, low density, ease of processability and ease of handling. Moreover, such composites cover range of applications from everyday use to high-tech applications. Various polymeric textiles such as fibers, yarn, woven, nonwoven, knitted, as well as their hybrid composites have been extensively manipulated physically and/or chemically to act as shielding against such harmful radiations. This review encompasses from basic concept of EMI shielding for beginner to the latest research in polymeric-based textile materials synthesis for experts, covering detailed mechanisms with schematic illustration. The review also covers the gap of materials synthesis and their application on polymeric textiles which could be used for EMI shielding applications. Furthermore, recent research regarding rendering EMI shielding properties at various stages of polymeric textile development is provided for readers with critical analysis. Lastly, the applications along with environmental compliance have also been presented for better understanding.

A model to predict the effective permittivity of heterogeneous multiphase structures with new bounds

2018 ◽  
Vol 141 ◽  
pp. 260-268 ◽  
Author(s):  
Younes Jarmoumi ◽  
Soukaina Najah ◽  
Fatna Benzouine ◽  
Abdelali Derouiche
Keyword(s):  
Effective Permittivity

Effects of material texture and packing density on the interfacial polarization of granular soils

Geophysics ◽  
2021 ◽  
pp. 1-58
Author(s):  
Hang Chen ◽  
Qifei Niu
Keyword(s):  
Electrical Conductivity ◽  
Packing Density ◽  
Characteristic Frequency ◽  
Effective Permittivity ◽  
Scale Up ◽  
Interfacial Polarization ◽  
Granular Soils ◽  
Geologic Materials ◽  
Effective Electrical Conductivity ◽  
Material Texture

Many electrical and electromagnetic (EM) methods operate at MHz frequencies, at which the interfacial polarization occurring at the solid-liquid interface in geologic materials may dominate the electrical signals. To correctly interpret electrical/EM measurements, it is therefore critical to understand how the interfacial polarization influences the effective electrical conductivity and permittivity spectra of geologic materials. We have used pore-scale simulation to study the role of material texture and packing in interfacial polarization in water-saturated granular soils. Synthetic samples with varying material textures and packing densities are prepared with the discrete element method. The effective electrical conductivity and permittivity spectra of these samples are determined by numerically solving the Laplace equation in a representative elementary volume of the samples. The numerical results indicate that the effective permittivity of granular soils increases as the frequency decreases due to the polarizability enhancement from the interfacial polarization. The induced permittivity increment is mainly influenced by the packing state of the samples, increasing with the packing density. Material textures such as the grain shape and size distribution may also affect the permittivity increment, but their effects are less significant. The frequency characterizing the interfacial polarization (i.e., the characteristic frequency) is mainly related to the electrical contrast of the solid and water phases. The model based on the traditional differential effective medium (DEM) theory significantly underestimates the permittivity increment by a factor of more than two and overestimates the characteristic frequency by approximately 1 MHz. These inaccurate predictions are due to the fact that the electrical interactions between neighboring grains are not considered in the DEM theory. A simple empirical equation is suggested to scale up the theoretical depolarization factor of grains entering the DEM theory to account for the interaction of neighboring grains in granular soils.

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