scholarly journals Polyetherimide Foams Filled with Low Content of Graphene Nanoplatelets Prepared by scCO2 Dissolution

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 328 ◽  
Author(s):  
Hooman Abbasi ◽  
Marcelo Antunes ◽  
José Velasco
Keyword(s):  
Electromagnetic Interference ◽  
Cellular Structure ◽  
Electrostatic Discharge ◽  
Graphene Nanoplatelets ◽  
Conductive Network ◽  
Emi Shielding ◽  
Melt Mixing ◽  
Degradation Behaviour ◽  
Increasing Trend ◽  
One Step

Polyetherimide (PEI) foams with graphene nanoplatelets (GnP) were prepared by supercritical carbon dioxide (scCO2) dissolution. Foam precursors were prepared by melt-mixing PEI with variable amounts of ultrasonicated GnP (0.1–2.0 wt %) and foamed by one-step scCO2 foaming. While the addition of GnP did not significantly modify the cellular structure of the foams, melt-mixing and foaming induced a better dispersion of GnP throughout the foams. There were minor changes in the degradation behaviour of the foams with adding GnP. Although the residue resulting from burning increased with augmenting the amount of GnP, foams showed a slight acceleration in their primary stages of degradation with increasing GnP content. A clear increasing trend was observed for the normalized storage modulus of the foams with incrementing density. The electrical conductivity of the foams significantly improved by approximately six orders of magnitude with only adding 1.5 wt % of GnP, related to an improved dispersion of GnP through a combination of ultrasonication, melt-mixing and one-step foaming, leading to the formation of a more effective GnP conductive network. As a result of their final combined properties, PEI-GnP foams could find use in applications such as electrostatic discharge (ESD) or electromagnetic interference (EMI) shielding.

scholarly journals Conductive thermoplastic vulcanizates based on carbon black-filled bromo-isobutylene-isoprene rubber (BIIR)/polypropylene (PP)

2021 ◽  
Vol 60 (1) ◽  
pp. 303-312
Author(s):  
Yunyun Huang ◽  
Zhi Liu ◽  
Hongyan Xu ◽  
Ruoyu Hong
Keyword(s):  
Carbon Black ◽  
Electromagnetic Interference ◽  
Emi Shielding ◽  
Step Method ◽  
Melt Mixing ◽  
Uniform Dispersion ◽  
Thermoplastic Vulcanizates ◽  
Approach Method ◽  
One Step ◽  
Isoprene Rubber

Abstract Conductive elastomer materials based on carbon black (CB) filled bromo-isobutylene-isoprene rubber (BIIR)/polypropylene (PP) thermoplastic vulcanizate (TPV) were prepared by two step method and one step method. The microstructure, mechanical properties, electrical resistivity, thermal stability, electromagnetic interference shielding performance, and fracture surface morphology of composite materials were studied. The result shows the serious aggregation of CB in one-step TPV, but the uniform dispersion of CB in two-step TPV. In addition, the two-step TPV shows a higher electromagnetic interference (EMI) shielding performance and lower conductivity penetration threshold. The penetration threshold of the two-step TPV is 9.1%, and the maximum reflection loss of the two-step TPV16 is −29.5 dB. Therefore, this research offers an uncomplicated and scalable melt mixing approach method to manufacture conductive thermoplastic vulcanizates with excellent EMI shielding.

DISPERSION OF COBALT FERRITE FUNCTIONALIZED GRAPHENE NANOPLATELETS IN PLA FOR EMI SHIELDING APPLICATIONS

2021 ◽  
Author(s):  
KANAT ANURAKPARADORN ◽  
ALAN TAUB ◽  
ERIC MICHIELSSEN
Keyword(s):  
Functional Groups ◽  
Electromagnetic Interference ◽  
High Speed ◽  
Magnetic Particles ◽  
Cobalt Ferrite ◽  
Reduction Process ◽  
Cost Effective ◽  
Graphene Nanoplatelets ◽  
Angle Of Incidence ◽  
Emi Shielding

The proliferation of wireless technology calls for the development of cost-effective Electromagnetic Interference (EMI) shielding materials that reduce the susceptibility of high-speed electronic circuits to undesired incoming radiation. Ideally, such materials offer protection over wide frequency ranges and are insensitive to the polarization or angle of incidence of the impinging fields. Here, next-generation EMI shielding materials composed of polymer composites with conductive and magnetic fillers are introduced. It is shown that careful control of the concentration and dispersion of the polymers’ conductive and magnetic constituents permits tuning of the composites’ intrinsic electrical and magnetic properties. The resulting EMI shields are lightweight, cheap and offer greater protection than traditional metal gaskets and foams. In this work, cobalt ferrite magnetic nanoparticles (CoFe2O4) decorated on graphene-based material were dispersed in polylactic acid (PLA) matrix for high EM absorption level in X-band (8-12 GHz). The decoration of the magnetic particles was performed on the as-prepared conductive graphene nanoplatelets (GNP) and reduced graphene oxide (rGO). GNP composites exhibited higher DC conductivity, and permittivity than rGO composites. This is attributed to issues associated with the reduction process, including a lack of conductivity due to the insulated oxygen functional groups and the reduction in the lateral size. Compared with rGOs, the lack of out-plane functional groups causes the cobalt ferrite nanoparticles to agglomerate and not cover the entire surface of the GNPs. These morphological differences improve the magnetization and EM absorption of the composite system. The compatibilizer (pyrene-PLA-OH) was added to the composites to enhance dispersion of the GNPs in the polymer matrix which benefits in higher absorption of the shield. The influence of the compatibilizer on parameter, the reflection loss (RL) of the composite were determined from the characterized intrinsic properties

EMI Shielding Properties of Polymer Blend with the Inclusion of Graphene Nano Platelets

2021 ◽  
Vol 875 ◽  
pp. 160-167
Author(s):  
Muhammad Fayzan Shakir ◽  
Asra Tariq
Keyword(s):  
Electromagnetic Interference ◽  
Coaxial Cable ◽  
Network Analyzer ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Electrically Conductive ◽  
Emi Shielding Effectiveness ◽  
Increasing Trend ◽  
Shielding Properties ◽  
Basic Prediction

Polymer nano composites based on poly vinyl chloride matrix were fabricated using polyaniline (PANI) and graphene nano platelets (GNP) as electrically conductive nano filler for the application of electromagnetic interference (EMI) shielding. DC conductivity was first evaluated by using cyclic voltammetry and found an increasing trend of electrical conductivity as PANI and GNP was added in PVC matrix that confirms the formation of electrically conductive network structure. Dielectric properties like dielectric constant, dielectric loss and AC conductivity were evaluated in frequency range of 100 Hz to 3 MHz that gives basic prediction for EMI shielding effectiveness. Vector Network Analyzer (VNA) was used to assess EMI shielding properties using coaxial cable method in 11GHz to 20GHz range and it was found that a maximum of 29 dB shielding was archived with the incorporation of 15 wt% of PANI in PVC. This value increased to 56 dB as 5 wt% GNP added in PVC/PANI 15 wt% blend. Interaction of matrix with filler, nature of filler and dispersion of filler in matrix are the key parameters for achieving high shielding effectiveness.

Asymmetric conductive polymer composite foam for absorption dominated ultra-efficient electromagnetic interference shielding with extremely low reflection characteristics

2020 ◽  
Vol 8 (18) ◽  
pp. 9146-9159 ◽  
Author(s):  
Hongji Duan ◽  
Huixin Zhu ◽  
Jiefeng Gao ◽  
Ding-Xiang Yan ◽  
Kun Dai ◽  
...  
Keyword(s):  
Network Design ◽  
Polymer Composite ◽  
Electromagnetic Interference ◽  
Conductive Polymer ◽  
Conductive Network ◽  
Emi Shielding ◽  
Electromagnetic Interference Shielding ◽  
Composite Foam ◽  
Conductive Polymer Composite ◽  
Reflection Characteristics

An ultraefficient EMI shielding WPU composite foam with extremely low reflection is achieved via ingenious asymmetric conductive network design.

Highly stretchable electromagnetic interference (EMI) shielding segregated polyurethane/carbon nanotube composites fabricated by microwave selective sintering

2019 ◽  
Vol 7 (26) ◽  
pp. 7938-7946 ◽  
Author(s):  
Dong Feng ◽  
Dawei Xu ◽  
Qingqing Wang ◽  
Pengju Liu
Keyword(s):  
Carbon Nanotube ◽  
Electromagnetic Interference ◽  
Conductive Network ◽  
Emi Shielding ◽  
Efficient Strategy ◽  
Nanotube Composites ◽  
Highly Stretchable ◽  
Carbon Nanotube Composites

Microwave selective sintering is a green and efficient strategy to construct a segregated conductive network.

scholarly journals Dependence of electromagnetic interference shielding ability of conductive polymer composite foams with hydrophobic properties on cellular structure

2020 ◽  
Vol 8 (22) ◽  
pp. 7401-7410 ◽  
Author(s):  
Biao Zhao ◽  
Ruoming Wang ◽  
Yang Li ◽  
Yumei Ren ◽  
Xiao Li ◽  
...  
Keyword(s):  
Polymer Composites ◽  
Electromagnetic Interference ◽  
Cellular Structure ◽  
Conductive Polymer ◽  
Emi Shielding ◽  
Electromagnetic Interference Shielding ◽  
Hydrophobic Properties ◽  
Conductive Polymer Composites ◽  
Composite Foams ◽  
Shielding Properties

The introduction of a cellular structure in conductive polymer composites is supposed to be an effective way to ameliorate the electromagnetic interference (EMI) shielding properties.

scholarly journals Synergistic Manipulation of Zero-Dimension and One-Dimension Hybrid Nanofillers in Multi-Layer Two-Dimension Thin Films to Construct Light Weight Electromagnetic Interference Material

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3278
Author(s):  
Bihui Jin ◽  
Feiran Meng ◽  
Haoyu Ma ◽  
Bowen Zhang ◽  
Pengjian Gong ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
Cellular Structure ◽  
Crystalline Polymer ◽  
Expansion Ratio ◽  
One Dimension ◽  
Emi Shielding ◽  
Two Dimension ◽  
Thin Walls ◽  
Large Expansion ◽  
Air Cells

Nanocomposite foam with a large expansion ratio and thin cell walls is promising for electromagnetic interference (EMI) shielding materials, due to the low electromagnetic (EM) reflection and high EM absorption. To overcome the dimensional limitation from two-dimension (2D) thin walls on the construction of conductive network, a strategy combining hybrid conductive nanofillers in semi-crystalline matrix together with supercritical CO2 (scCO2) foaming was applied: (1) one-dimension (1D) CNTs with moderate aspect ratio was used to minimize the dimensional confinement from 2D thin walls while constructing the main EM absorbing network; (2) zero-dimension (0D) carbon black (CB) with no dimensional confinement was used to connect the separated CNTs in thin walls and to expand the EM absorbing network; (3) scCO2 foaming was applied to obtain a cellular structure with multi-layer thin walls and a large amount of air cells to reduce the reflected EM; (4) semi-crystalline polymer was selected so that the rheological behavior could be adjusted by optimizing crystallization and filler content to regulate the cellular structure. Consequently, an advanced material featured as lightweight, high EM absorption and low EM reflection was obtained at 0.48 vol.% hybrid nanofillers and a density of 0.067 g/cm3, whose specific EMI shielding performance was 183 dB cm3/g.

EMI Shielding Effectiveness of CNTs Composites

2013 ◽  
Vol 331 ◽  
pp. 439-442 ◽  
Author(s):  
Ping Li ◽  
Aik Seng Low ◽  
Yue Yan Shan ◽  
Guat Choon Ong ◽  
Xi Jiang Yin
Keyword(s):  
Carbon Nanotubes ◽  
Electromagnetic Interference ◽  
Conductive Network ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Frequency Range ◽  
Electromagnetic Interference Shielding ◽  
Emi Shielding Effectiveness ◽  
Electromagnetic Interference Shielding Effectiveness ◽  
5 Ghz

A carbon nanotubes (CNTs) composite and its electromagnetic interference shielding effectiveness (SE) were investigated. Its absorptance, reflectance and shielding effectiveness (SE) were analysed. The CNTs composite has a shielding effectiveness (SE) of more than 25 dB (>99.68%) in frequency range from 30 MHz to 5 GHz. The testing results also demonstrate that the shielding mechanism of the CNTs composite is mainly EMI absorption of electromagnitic radiation. The high SE of the CNTs composite in the study is attributed to a high aspect ratio (>3000) and good conductive network of CNTs within the composite.

Tailoring Ti3C2Txnanosheets to tune local conductive network as an environmentally friendly material for highly efficient electromagnetic interference shielding

Nanoscale ◽  
2019 ◽  
Vol 11 (13) ◽  
pp. 6080-6088 ◽  
Author(s):  
Peng He ◽  
Xi-Xi Wang ◽  
Yong-Zhu Cai ◽  
Jin-Cheng Shu ◽  
Quan-Liang Zhao ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Electromagnetic Interference ◽  
High Performance ◽  
Environmentally Friendly ◽  
Atomic Layer ◽  
Conductive Network ◽  
Emi Shielding ◽  
Electromagnetic Interference Shielding ◽  
Highly Efficient

Atomic layer tailoring (ALT) the layer thickness of Ti3C2TxMXenes to induce the formation of a local conductive network, as an environmentally friendly material for high-performance EMI shielding.

scholarly journals Effects of Graphene Nanoplatelets and Cellular Structure on the Thermal Conductivity of Polysulfone Nanocomposite Foams

Polymers ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 25 ◽  
Author(s):  
Hooman Abbasi ◽  
Marcelo Antunes ◽  
José Ignacio Velasco
Keyword(s):  
Thermal Conductivity ◽  
Relative Density ◽  
Supercritical Co2 ◽  
Cellular Structure ◽  
Graphene Nanoplatelets ◽  
Nanocomposite Foams ◽  
Increasing Trend ◽  
The Impact ◽  
Opening Up ◽  
Enhanced Thermal Conductivity

Polysulfone (PSU) foams containing 0–10 wt% graphene nanoplatelets (GnP) were prepared using two foaming methods. Alongside the analysis of the cellular structure, their thermal conductivity was measured and analyzed. The results showed that the presence of GnP can affect the cellular structure of the foams prepared by both water vapor induced phase separation (WVIPS) and supercritical CO2 (scCO2) dissolution; however, the impact is greater in the case of foams prepared by WVIPS. In terms of thermal conductivity, the analysis showed an increasing trend by incrementing the amount of GnP and increasing relative density, with the tortuosity of the cellular structure, dependent on the used foaming method, relative density, and amount of GnP, playing a key role in the final value of thermal conductivity. The combination of all these factors showed the possibility of preparing PSU-GnP foams with enhanced thermal conductivity at lower GnP amount by carefully controlling the cellular structure and relative density, opening up their use in lightweight heat dissipators.

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