scholarly journals Hierarchically Multifunctional Polyimide Composite Films with Strongly Enhanced Thermal Conductivity

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Yongqiang Guo ◽  
Hua Qiu ◽  
Kunpeng Ruan ◽  
Yali Zhang ◽  
Junwei Gu
Keyword(s):  
Thermal Conductivity ◽  
Electromagnetic Interference ◽  
Composite Films ◽  
Expanded Graphite ◽  
Electric Heating ◽  
Processing Unit ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Heat Accumulation ◽  
Central Processing

AbstractThe development of lightweight and integration for electronics requires flexible films with high thermal conductivity and electromagnetic interference (EMI) shielding to overcome heat accumulation and electromagnetic radiation pollution. Herein, the hierarchical design and assembly strategy was adopted to fabricate hierarchically multifunctional polyimide composite films, with graphene oxide/expanded graphite (GO/EG) as the top thermally conductive and EMI shielding layer, Fe3O4/polyimide (Fe3O4/PI) as the middle EMI shielding enhancement layer and electrospun PI fibers as the substrate layer for mechanical improvement. PI composite films with 61.0 wt% of GO/EG and 23.8 wt% of Fe3O4/PI exhibits high in-plane thermal conductivity coefficient (95.40 W (m K)−1), excellent EMI shielding effectiveness (34.0 dB), good tensile strength (93.6 MPa) and fast electric-heating response (5 s). The test in the central processing unit verifies PI composite films present broad application prospects in electronics fields.

Fabrication and characterization of organic semiconductor for electromagnetic interference shielding material

2011 ◽  
Vol 31 (4) ◽  
Author(s):  
Habibun Nabi Muhammad Ekramul Mahmud ◽  
Anuar Kassim
Keyword(s):  
Conducting Polymer ◽  
Polymer Composite ◽  
Indium Tin Oxide ◽  
Electromagnetic Interference ◽  
Composite Films ◽  
Oxide Glass ◽  
Poly Vinyl Alcohol ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Shielding Material

Abstract Conducting polymer films produced by electropolymerization technique are highly conductive, simple, and suitable for use especially in electronic devices. An attempt has been made to produce polypyrrole-poly(vinyl alcohol) (PPy-PVA) conducting polymer composite films using 0.1 m p-toluene sulfonate dopant at a potential of 1.2 V (vs. standard calomel electrode) on indium tin oxide glass electrode. The potential application of the prepared PPy-PVA conducting polymer composite films as an electromagnetic interference (EMI) shielding material has been investigated in the present study. The EMI shielding effectiveness of PPy-PVA composite films prepared from different experimental conditions was analyzed in the microwave frequency range of 8–12 GHz. The shielding effectiveness of 45.67–35.7 dB has been demonstrated by PPy-PVA conducting polymer composite films, which appears to be very attractive in any EMI shielding applications where a minimum shielding effectiveness of 35 dB is required.

Researching on X-Band Electromagnetic Interference Shielding Efficiency of MWCNTs Buckypapers Inserted with Mn Nanopowder

NANO ◽  
2018 ◽  
Vol 13 (06) ◽  
pp. 1850061 ◽  
Author(s):  
Shaowei Lu ◽  
Yaoyao Bai ◽  
Jijie Wang ◽  
Chenxu Zhao ◽  
Wei Li ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
Energy Dispersive Spectrometer ◽  
Composite Films ◽  
Resin Matrix ◽  
Manufacturing Cost ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Filtration Method ◽  
Emi Shielding Effectiveness ◽  
X Band

Ultrathin multi-walled carbon nanotubes (MWCNTs) buckypapers inserted with Mn nanopowder were fabricated via vacuum filtration method, at a lower manufacturing cost and easier operation. The buckypapers were characterized structurally using scanning electron microscopy, energy-dispersive spectrometer and X-ray diffraction. Electromagnetic interference (EMI) shielding effectiveness (SE) of MWCNTs buckypapers inserted with Mn nanopowder (0–30[Formula: see text]wt.%) were tested in X-band (8.2–12.4[Formula: see text]GHz). When the blended Mn nanopowder content is 20[Formula: see text]wt.%, the buckypaper exhibits much higher EMI SE of average value up to 42[Formula: see text]dB with the thickness of only 0.11[Formula: see text]mm. Further, this buckypaper is flexible and lightweight, and can be integrated with resin matrix composites. Thus, the results and techniques promise a simple and effective approach to achieve lightweight and ultrathin composite films for a wide application prospect in the field of EMI shielding and microwave absorption.

Ultrathin flexible reduced graphene oxide/cellulose nanofiber composite films with strongly anisotropic thermal conductivity and efficient electromagnetic interference shielding

2017 ◽  
Vol 5 (15) ◽  
pp. 3748-3756 ◽  
Author(s):  
Weixing Yang ◽  
Zedong Zhao ◽  
Kai Wu ◽  
Rui Huang ◽  
Tianyu Liu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Graphene Oxide ◽  
Electromagnetic Interference ◽  
Composite Films ◽  
Emi Shielding ◽  
Electromagnetic Interference Shielding ◽  
Nanofiber Composite ◽  
Anisotropic Thermal Conductivity ◽  
Reduced Graphene ◽  
Cnf Films

In this study, ultrathin flexible RGO/CNF films with outstanding EMI shielding performances and strongly anisotropic thermal conductivity were successfully fabricated.

Flexible GnPs/EPDM with Excellent Thermal Conductivity and Electromagnetic Interference Shielding Properties

NANO ◽  
2019 ◽  
Vol 14 (06) ◽  
pp. 1950075 ◽  
Author(s):  
Shaowei Lu ◽  
Yaoyao Bai ◽  
Jijie Wang ◽  
Dandan Chen ◽  
Keming Ma ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electromagnetic Interference ◽  
Rubber Matrix ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Emi Shielding Effectiveness ◽  
X Band ◽  
Cost Efficient ◽  
Emi Se ◽  
Shielding Material

As the portable device hardware has been increasing at a noticeable rate, ultrathin flexible materials with the combination of high thermal conductivity and excellent electromagnetic interference (EMI) shielding performance are urgently needed. Here, we fabricated ethylene propylene diene monomer rubber with different loading graphene nanoplatelets (GnPs/EPDM) by a cost-efficient approach, which combines mixing, ultrasonication and compression. Further investigation demonstrates that the 8[Formula: see text]wt.% GnPs/EPDM with only 0.3[Formula: see text]mm in thickness shows excellent electrical conductivity (28.3[Formula: see text]S/m), thermal conductivity (0.79[Formula: see text]W/m[Formula: see text]K) and good mechanical properties. Besides, the 8[Formula: see text]wt.% GnPs/EPDM exhibits an EMI shielding effectiveness (SE) up to 33[Formula: see text]dB in the X-band (8.2–12.4[Formula: see text]GHz) and 35[Formula: see text]dB in the Ku-band (12.4–18[Formula: see text]GHz), superior to most of the reported rubber matrix. Additionally, the GnPs/EPDM shows excellent flexibility and stability with 95% and 94% retention of EMI SE even after repeated bending for 5000 times and corrosion (under 5% NaCl environment) for a week. Our flexible EMI shielding material will benefit the fast-growing next-generation commercial portable flexible electrons.

scholarly journals Ultrathin flexible graphene films with high thermal conductivity and excellent EMI shielding performance using large-sized graphene oxide flakes

RSC Advances ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 1419-1427 ◽  
Author(s):  
Shaofeng Lin ◽  
Su Ju ◽  
Jianwei Zhang ◽  
Gang Shi ◽  
Yonglyu He ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Graphene Oxide ◽  
Electromagnetic Interference ◽  
Electronic Devices ◽  
High Thermal Conductivity ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Emi Shielding Effectiveness ◽  
Graphene Films ◽  
Thermal Conducting

As the demand for wearable and foldable electronic devices increases rapidly, ultrathin and flexible thermal conducting films with exceptional electromagnetic interference (EMI) shielding effectiveness (SE) are greatly needed.

scholarly journals Ultrathin, Lightweight, and Flexible CNT Buckypaper Enhanced Using MXenes for Electromagnetic Interference Shielding

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Rongliang Yang ◽  
Xuchun Gui ◽  
Li Yao ◽  
Qingmei Hu ◽  
Leilei Yang ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
High Performance ◽  
Electronic Devices ◽  
Deposition Process ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Emi Shielding Effectiveness ◽  
X Band ◽  
Wearable Electronic Devices ◽  
Emi Se

AbstractLightweight, flexibility, and low thickness are urgent requirements for next-generation high-performance electromagnetic interference (EMI) shielding materials for catering to the demand for smart and wearable electronic devices. Although several efforts have focused on constructing porous and flexible conductive films or aerogels, few studies have achieved a balance in terms of density, thickness, flexibility, and EMI shielding effectiveness (SE). Herein, an ultrathin, lightweight, and flexible carbon nanotube (CNT) buckypaper enhanced using MXenes (Ti3C2Tx) for high-performance EMI shielding is synthesized through a facile electrophoretic deposition process. The obtained Ti3C2Tx@CNT hybrid buckypaper exhibits an outstanding EMI SE of 60.5 dB in the X-band at 100 μm. The hybrid buckypaper with an MXene content of 49.4 wt% exhibits an EMI SE of 50.4 dB in the X-band with a thickness of only 15 μm, which is 105% higher than that of pristine CNT buckypaper. Furthermore, an average specific SE value of 5.7 × 104 dB cm2 g−1 is exhibited in the 5-μm hybrid buckypaper. Thus, this assembly process proves promising for the construction of ultrathin, flexible, and high-performance EMI shielding films for application in electronic devices and wireless communications.

Dual percolations of electrical conductivity and electromagnetic interference shielding in progressively agglomerated CNT/polymer nanocomposites

2021 ◽  
pp. 108128652110214
Author(s):  
Xiaodong Xia ◽  
George J. Weng
Keyword(s):  
Experimental Data ◽  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Percolation Threshold ◽  
Polymer Nanocomposites ◽  
Electromagnetic Interference ◽  
Effective Medium Theory ◽  
Scale Model ◽  
Shielding Effectiveness ◽  
Emi Shielding

Recent experiments have revealed two distinct percolation phenomena in carbon nanotube (CNT)/polymer nanocomposites: one is associated with the electrical conductivity and the other is with the electromagnetic interference (EMI) shielding. At present, however, no theories seem to exist that can simultaneously predict their percolation thresholds and the associated conductivity and EMI curves. In this work, we present an effective-medium theory with electrical and magnetic interface effects to calculate the overall conductivity of a generally agglomerated nanocomposite and invoke a solution to Maxwell’s equations to calculate the EMI shielding effectiveness. In this process, two complex quantities, the complex electrical conductivity and complex magnetic permeability, are adopted as the homogenization parameters, and a two-scale model with CNT-rich and CNT-poor regions is utilized to depict the progressive formation of CNT agglomeration. We demonstrated that there is indeed a clear existence of two separate percolative behaviors and showed that, consistent with the experimental data of poly-L-lactic acid (PLLA)/multi-walled carbon nanotube (MWCNT) nanocomposites, the electrical percolation threshold is lower than the EMI shielding percolation threshold. The predicted conductivity and EMI shielding curves are also in close agreement with experimental data. We further disclosed that the percolative behavior of EMI shielding in the overall CNT/polymer nanocomposite can be illustrated by the establishment of connective filler networks in the CNT-poor region. It is believed that the present research can provide directions for the design of CNT/polymer nanocomposites in the EMI shielding components.

scholarly journals A Healable and Mechanically Enhanced Composite with Segregated Conductive Network Structure for High-Efficient Electromagnetic Interference Shielding

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Ting Wang ◽  
Wei-Wei Kong ◽  
Wan-Cheng Yu ◽  
Jie-Feng Gao ◽  
Kun Dai ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
Diels Alder ◽  
Electrostatic Attraction ◽  
List Type ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Electromagnetic Interference Shielding ◽  
Elongation At Break ◽  
High Efficient ◽  
Emi Se

Highlights The cationic waterborne polyurethanes microspheres with Diels-Alder bonds were synthesized for the first time. The electrostatic attraction not only endows the composite with segregated structure to gain high electromagnetic-interference shielding effectiveness, but also greatly enhances mechanical properties. Efficient healing property was realized under heating environment. Abstract It is still challenging for conductive polymer composite-based electromagnetic interference (EMI) shielding materials to achieve long-term stability while maintaining high EMI shielding effectiveness (EMI SE), especially undergoing external mechanical stimuli, such as scratches or large deformations. Herein, an electrostatic assembly strategy is adopted to design a healable and segregated carbon nanotube (CNT)/graphene oxide (GO)/polyurethane (PU) composite with excellent and reliable EMI SE, even bearing complex mechanical condition. The negatively charged CNT/GO hybrid is facilely adsorbed on the surface of positively charged PU microsphere to motivate formation of segregated conductive networks in CNT/GO/PU composite, establishing a high EMI SE of 52.7 dB at only 10 wt% CNT/GO loading. The Diels–Alder bonds in PU microsphere endow the CNT/GO/PU composite suffering three cutting/healing cycles with EMI SE retention up to 90%. Additionally, the electrostatic attraction between CNT/GO hybrid and PU microsphere helps to strong interfacial bonding in the composite, resulting in high tensile strength of 43.1 MPa and elongation at break of 626%. The healing efficiency of elongation at break achieves 95% when the composite endured three cutting/healing cycles. This work demonstrates a novel strategy for developing segregated EMI shielding composite with healable features and excellent mechanical performance and shows great potential in the durable and high precision electrical instruments.

Effect of Polymer Matrix in Polymer/trGO Nano-Composite for EMI Shielding Application in Microwave and Infrared Region

2021 ◽  
Vol 875 ◽  
pp. 153-159
Author(s):  
Khadija Zubair ◽  
Muhammad Fayzan Shakir
Keyword(s):  
Composite Films ◽  
Acrylonitrile Butadiene Styrene ◽  
Infrared Region ◽  
Network Analyzer ◽  
Shielding Effectiveness ◽  
Interconnected Network ◽  
Emi Shielding ◽  
Nano Composite ◽  
Reduced Graphene ◽  
Butadiene Styrene

Thermally reduced graphene oxide (trGO) was successfully prepared and confirmed by XRD then dispersed in polystyrene (PS) and Acrylonitrile-Butadiene-Styrene (ABS) polymers and evaluated for EMI shielding in microwave and infrared (IR) region. Thickness of prepared polymer/trGO composite films were 200-250 micron. It was observed that trGO has more compatibility with PS then ABS and dispersed more easily and uniformly in PS than ABS. This effect was also observed in IR shielding as ABS+15trGO have 3% transmission and PS+1% trGO have 1.5% transmission. Maximum 29 dB and 25 dB shielding effectiveness was measured by vector network analyzer (VNA) in microwave region (9-18 GHz) of PS+2% trGO and ABS+2% trGo composite respectively. These results clearly indicating that trGO is more compatible with PS than ABS and form more stable and mature interconnected network structure in PS at lower concentrations.

Electromagnetic interference shielding effectiveness of polypyrrole-silver nanocomposite films on silane-modified flexible sheet

2021 ◽  
pp. 095400832110645
Author(s):  
Karim Benzaoui ◽  
Achour Ales ◽  
Ahmed Mekki ◽  
Abdelhalim Zaoui ◽  
Boudjemaa Bouaouina ◽  
...  
Keyword(s):  
Surface Treatment ◽  
Electromagnetic Interference ◽  
Nanocomposite Films ◽  
Electrical Characteristics ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Electromagnetic Interference Shielding ◽  
Silver Nanocomposite ◽  
Electromagnetic Interference Shielding Effectiveness ◽  
Emi Se

The conventional electromagnetic interference (EMI) shielding materials are being gradually replaced by a new generation of supported conducting polymer composites (CPC) films due to their many advantages. This work presents a contribution on the effects of silane surface–modified flexible polypyrrole-silver nanocomposite films on the electromagnetic interference shielding effectiveness (EMI-SE). Thus, the UV-polymerization was used to in-situ deposit the PPy-Ag on the biaxial oriented polyethylene terephthalate (BOPET) flexible substrates whose surfaces were treated by 3-aminopropyltrimethoxysilane (APTMS). X-ray Photoelectron Spectroscopy (XPS) analyzes confirmed the APTMS grafting procedure. Structural, morphological, thermal, and electrical characteristics of the prepared films were correlated to the effect of substrate surface treatment. Thereafter, EMI-SE measurements of the elaborated films were carried out as per ASTM D4935 standard for a wide frequency band extending from 50 MHz to 18 GHz. The obtained results confirmed that the APTMS-treated BOPET film exhibit higher EMI shielding performance and better electrical characteristics compared to the untreated film. In fact, a 32% enhancement of EMI-SE was noted for the treated films compared to the untreated ones. Overall, these results put forward the role played by the surface treatment in strengthening the position of flexible PPy-Ag supported films as high-performance materials in electronic devices and electromagnetic interference shielding applications.

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