Absorption-dominant EMI shielding polymer composite foams: Microstructure and geometry optimization

Ma, Li; Hamidinejad, Mahdi; Wei, Lingfen; Zhao, Biao; Park, Chul

doi:10.1016/j.mtphys.2022.100940

Cited by 36 publications

(33 citation statements)

References 69 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From our previous work, when the single-layer EMI shielding material is thin, internal multi-reflection can play a significant role in its reflectance, resulting in a thickness-dependent R -value due to interference with surface reflection. 74 In this work, to eliminate the effect of muti-reflection in the shielding layer, the corresponding thickness of each shielding layer was guided by theoretical calculations. As shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…[47][48][49] These interfaces provide additional EM wave attenuation capabilities by prolonging the EM wave propagation path through internal scattering with an equivalent conductivity to their solid counterparts. 50,51 Combining these two strategies, Duan et al, 52 developed a layered polymer composite foam as the absorption phase, which included a layer of heterostructured WPU/FeCo@rGO composite foam and a layer of WPU foam layer. In the meantime, a layer of conductive Ag-coated polymer bead particles was deposited as the shielding layer.…”

Section: New Conceptsmentioning

confidence: 99%

See 1 more Smart Citation

Layered polymer composite foams for broadband ultra-low reflectance EMI shielding: a computationally guided fabrication approach

Park

Hamidinejad

et al. 2023

Mater. Horiz.

Self Cite

View full text Add to dashboard Cite

show abstract

Section: Resultsmentioning

confidence: 99%

Section: New Conceptsmentioning

confidence: 99%

Layered polymer composite foams for broadband ultra-low reflectance EMI shielding: a computationally guided fabrication approach

Park

Hamidinejad

et al. 2023

Mater. Horiz.

Self Cite

View full text Add to dashboard Cite

show abstract

“…As mentioned in Section , multilayer EMI shielding materials would potentially show great promise as EMI shielding materials with fully absorption-dominant behavior at a given frequency band. , However, the performance of such microwave absorbers is inexorably dictated by the dielectric and magnetic properties of each layer . This effect can be described by the impedance conversion equation, which relates to the normalized input impedance ( Z i ) of a multilayer structure with i layers to the intrinsic impedance (η i ), the propagation constant (γ i ), and the thickness ( t i ) of the layers, as what follows: , …”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, a larger conductivity of the aerogels will potentially increase their absorption capability. This is caused by prolonging the wave’s trajectory due to scattering as a result of the impedance mismatch between the rGO stacks/air interfaces within the highly porous structure. , In order to specify the portions of the reflected, absorbed, and transmitted waves, their corresponding percent power coefficients are shown in Figure d for the fabricated aerogels. From the unreduced GO aerogel to the aerogel reduced at 800 °C, the simultaneous gradual decrease in transmittivity (from ∼98 to <1%) and increase in reflectivity (from 0 to ∼42%) are evident.…”

Section: Resultsmentioning

confidence: 99%

Incorporating Loss Factor Modular Design for Full Ku-Band Microwave Attenuation in Double-Layered Graphene Aerogels

Ashouri-Sanjani,

Salari,

Rahmati

et al. 2023

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

The fabrication of absorption-dominant electromagnetic interference (EMI) shielding materials is a pressing priority to prevent secondary electromagnetic pollution in miniaturized electronic devices and communication systems. Meeting this goal has remained a tough challenge to keep pace with the rapid evolution of electronics due to the complex compositional and structural design and narrow operating bands. This work articulates a sound and simple strategy to precisely modulate the electrical conductivity of reduced graphene oxide (rGO), as the building block in lightweight double-layered rGOfilm/rGO-aerogel/polyvinyl-alcohol (PVA) composites, for efficient microwave absorption over the entire Ku-band frequency range. These constructs reasonably comprised a porous absorption structure built from parallel rGO sheets aligned and prepared via freeze casting followed by freeze drying. The electrical conductivity and impedance of this layer were tuned by varying the annealing temperature from 400 to 800 °C, thereby adjusting the degree of reduction and the absorption characteristic. This layer was backed by a highly conductive rGO film reduced at a high temperature of 1000 °C, with a reflectivity of 97.5%. The incorporation of this film ensured high EMI shielding effectiveness of the double-layered structure through the absorption−reflection−reabsorption mechanism, consistent with the predicted values based on calculated loss factors and the input impedance of the structure. Accordingly, at an average EMI shielding effectiveness of 57.59 dB, the reflection shielding effectiveness (SE R ) and reflectivity (R) of the assembled composites were optimized to be as low as 0.22 dB and 0.049, respectively. This equates to approximately 99.999% shielding (SE T ) and ∼95% absorptivity (A) of the incident wave. This study opens new avenues for the development of lightweight (with a density as low as 15 mg/cm 3 ) absorption-dominant EMI shielding composite materials with promising EMI shielding efficiency and potential applications in modern electronics.

show abstract

“…So, from this, we can justify that the shielding effectiveness of multiple reflections mainly depends on the thickness and depth of the material and are closely related to the absorption mechanism. Therefore, multiple reflections are essential in porous structures and some solid geometries 34,50–52 …”

Section: Working Mechanism Of Electromagnetic Shieldingmentioning

confidence: 99%

Polyvinylidene fluoride—An advanced smart polymer for electromagnetic interference shielding applications—A novel review

Nivedhitha

Jeyanthi²

2023

Polymers for Advanced Techs

View full text Add to dashboard Cite

Emerging technology and modernization have become a worldwide threat to human life in all aspects. Worldwide, all countries are in the race to develop the most advanced electronic devices and gadgets as they reflect the country's superiority and economic development. Specialists have forecasted that during and after the pandemic, the addiction toward modern gadgets have increased by 40% among the people irrespective of age. A few researchers have reported that the world economy is dependent on and dominated by countries manufacturing semiconductors, mobiles, electronic chips, and so on. People started sensing that modern devices are like a boon, as their lives seem to be more connected and comfortable with all their needs and wants being fulfilled at their doorsteps. But this boon is slowly whirling as a severe threat to human lives. Due to this rapid usage of electronic devices, electromagnetic interference (EMI) is drastically growing, which is considered a global warning issue for commercial and biological systems. So advanced countries have decided to make EMI shielding a compulsory entity to be implemented in all advanced electronic devices. Though traditional materials like metals and carbon allotropes have excellent shielding properties, they cannot cope with today's mass production of modern devices. Thus, researchers had to find a suitable substitute material that should possess properties such as sustainability and biocompatibility to overcome problems faced by the conventional materials. Thus, polymers have come into the world of EMI shielding applications. Polyvinylidene fluoride (PVDF), a non‐conductive polymer from the family of Fluorocarbons, is creating history in the field of EMI shielding applications. PVDF astonished researchers with its versatile features, such as light weight, flexibility, and easy processibility with excellent dielectric and piezoelectric properties. Though they are poor in electrically conductive properties, incorporating metals, carbon allotropes, and metal oxides as fillers make them superior to the existing conventional materials. Thus, the main objective of this review article is to highlight the uniqueness of PVDF as an advanced polymer for EMI shielding applications. It has been noted that PVDF is more suitable for EMI shielding in X, K, and Ku band frequencies. But overall, we noticed that the performance of PVDF has a great impact by incorporating a combination of metal and carbon allotrope enhances the shielding effectiveness up to 65 dB in the Ku‐band (Kurz‐under) frequency band range of (12–18 GHz).

show abstract

Absorption-dominant EMI shielding polymer composite foams: Microstructure and geometry optimization

Cited by 36 publications

References 69 publications

Layered polymer composite foams for broadband ultra-low reflectance EMI shielding: a computationally guided fabrication approach

Layered polymer composite foams for broadband ultra-low reflectance EMI shielding: a computationally guided fabrication approach

Incorporating Loss Factor Modular Design for Full Ku-Band Microwave Attenuation in Double-Layered Graphene Aerogels

Polyvinylidene fluoride—An advanced smart polymer for electromagnetic interference shielding applications—A novel review

Contact Info

Product

Resources

About