scholarly journals Interface Engineered Microcellular Magnetic Conductive Polyurethane Nanocomposite Foams for Electromagnetic Interference Shielding

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Guolong Sang ◽  
Pei Xu ◽  
Tong Yan ◽  
Vignesh Murugadoss ◽  
Nithesh Naik ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
Magnetic Loss ◽  
Interfacial Polarization ◽  
Conductive Network ◽  
Shielding Effectiveness ◽  
Electromagnetic Interference Shielding ◽  
Multiple Reflections ◽  
Conduction Loss ◽  
Composite Foams ◽  
Emi Se

Abstract Lightweight microcellular polyurethane (TPU)/carbon nanotubes (CNTs)/ nickel-coated CNTs (Ni@CNTs)/polymerizable ionic liquid copolymer (PIL) composite foams are prepared by non-solvent induced phase separation (NIPS). CNTs and Ni@CNTs modified by PIL provide more heterogeneous nucleation sites and inhibit the aggregation and combination of microcellular structure. Compared with TPU/CNTs, the TPU/CNTs/PIL and TPU/CNTs/Ni@CNTs/PIL composite foams with smaller microcellular structures have a high electromagnetic interference shielding effectiveness (EMI SE). The evaporate time regulates the microcellular structure, improves the conductive network of composite foams and reduces the microcellular size, which strengthens the multiple reflections of electromagnetic wave. The TPU/10CNTs/10Ni@CNTs/PIL foam exhibits slightly higher SE values (69.9 dB) compared with TPU/20CNTs/PIL foam (53.3 dB). The highest specific EMI SE of TPU/20CNTs/PIL and TPU/10CNTs/10Ni@CNTs/PIL reaches up to 187.2 and 211.5 dB/(g cm−3), respectively. The polarization losses caused by interfacial polarization between TPU substrates and conductive fillers, conduction loss caused by conductive network of fillers and magnetic loss caused by Ni@CNT synergistically attenuate the microwave energy.

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.

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.

Tunable electromagnetic interference shielding ability of MXene/chitosan/silver nanowire sandwich films

2021 ◽  
pp. 2151041
Author(s):  
Wei Wang ◽  
Xiaoyu Bing ◽  
Yutong Zhou ◽  
Miaomiao Geng ◽  
Yanhu Zhan ◽  
...  
Keyword(s):  
Thin Films ◽  
Electromagnetic Interference ◽  
Hybrid Composites ◽  
Core Layer ◽  
Structure Design ◽  
Silver Nanowire ◽  
Shielding Effectiveness ◽  
Electromagnetic Interference Shielding ◽  
Electromagnetic Interference Shielding Effectiveness ◽  
Emi Se

The structural design of thin films is attracting attention in academia and industry in attempts to improve electromagnetic interference shielding effectiveness (EMI SE). In this study, MXene/chitosan/silver nanowire (AgNW) sandwich films, in which the AgNW core layer was bordered by two MXene/chitosan layers, were fabricated by vacuum-assisted filtration. Because of the interconnected AgNWs in the core layer and the aligned MXene sheets in the MXene/chitosan layers, the electrical conductivity of the sandwich film reached 11,459.1 S/m. Consequently, the sandwich film exhibited an SE value of 82.3 dB. What is more, when both the AgNW and MXene contents were 33.3%, the sandwich film’s EMI SE divided by its thickness was 26,167 dB/cm, which was much superior to the values reported for inorganic hybrid composites and polymer composites filled with hybrid fillers. Such a simple approach was proved to be an effective way for further structure design of thin films in EMI shielding field.

Microwave Irradiation of Graphene Aerogel and Its Use on the Electromagnetic Interference Shielding of BMI Nanocomposites

NANO ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. 2050143
Author(s):  
Bowen Feng ◽  
Wei Li ◽  
Fei Xue ◽  
Xingyu Tong ◽  
Jiaying Li ◽  
...  
Keyword(s):  
Self Assembly ◽  
Electromagnetic Interference ◽  
Chemical Reduction ◽  
Three Dimensional ◽  
Microwave Treatment ◽  
Shielding Effectiveness ◽  
Electromagnetic Interference Shielding ◽  
Graphene Aerogels ◽  
Electromagnetic Interference Shielding Effectiveness ◽  
Emi Se

In this work, graphene aerogels (GAs) with three-dimensional interconnected networks were prepared by chemical reduction and self-assembly of graphene oxide sheets. After microwave treatment, obtained microwave reduced graphene aerogels (MRGAs) were used in the preparation of bismaleimide (BMI) composites. The results show that the microwave treatment significantly enhanced the quality of GAs, and the three-dimensional networks in the GAs were well retained. Moreover, the MRGAs were highly efficient in endowing BMI with high electrical conductivity and excellent electromagnetic interference shielding effectiveness (EMI SE). The conductivity of MRGA/BMI composites was 42–68% higher than that of GA/BMI composites. When the filler content is 1.6 wt.%, the EMI SE of MRGA/BMI composite was 32.3% higher than that of GA/BMI composite in the X band.

Study of Mechanical, Electromagnetic, and Crystalline Properties of PP/SEBS/GNs Nano-Composites

2014 ◽  
Vol 910 ◽  
pp. 194-197
Author(s):  
Jia Horng Lin ◽  
Xiao Min Song ◽  
Chien Lin Huang ◽  
Ching Wen Lou
Keyword(s):  
Tensile Strength ◽  
Tensile Test ◽  
Electromagnetic Interference ◽  
Triblock Copolymer ◽  
Graphene Nanosheets ◽  
Electromagnetic Properties ◽  
Nano Composites ◽  
Shielding Effectiveness ◽  
Electromagnetic Interference Shielding ◽  
Emi Se

Polypropylene (PP) and styrene-ethylene-butylene-styrene triblock copolymer (SEBS) are blended at a ratio of 70/30 to serve as matrices, to which graphene nanosheets (GNs), the reinforcement, are then added to form PP/SEBS/GNs nanocomposites. A differential scanning calorimeter (DSC) test, tensile test, conductivity test, and electromagnetic interference shielding test are performed on the nanocomposites to examine the crystalline, mechanical, and electromagnetic properties. DSC results show that the content of GNs is proportional to the crystallization temperature of PP. The conductivity and electromagnetic inference shielding effectiveness (EMI SE) increase with an increase in the content of GNs, and can reach an optimal 0.244 S/m and 22 dB, respectively. The results of a tensile test show that an increasing content of GNs results in a decrease and then an increase in the tensile strength of the nanocomposites, until it reaches optimal tensile strength is 17.44 MPa.

scholarly journals Highly Bendable and Durable Waterproof Paper for Ultra-High Electromagnetic Interference Shielding

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1486 ◽  
Author(s):  
Fang Ren ◽  
Han Guo ◽  
Zheng-Zheng Guo ◽  
Yan-Ling Jin ◽  
Hong-Ji Duan ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
Silver Nanowires ◽  
Cellulose Fiber ◽  
Dip Coating ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Multiple Reflections ◽  
Water Contact ◽  
Practical Applications ◽  
Emi Se

An efficient electromagnetic interference (EMI) shielding paper with excellent water repellency and mechanical flexibility has been developed, by assembling silver nanowires (AgNWs) and hydrophobic inorganic ceramic on the cellulose paper, via a facile dip-coating preparation. Scanning electron microscope (SEM) observations confirmed that AgNWs were interconnected and densely coated on both sides of the cellulose fiber, which endows the as-prepared paper with high conductivity (33.69 S/cm in-plane direction) at a low AgNW area density of 0.13 mg/cm2. Owing to multiple reflections and scattering between the two outer highly conductive surfaces, the obtained composite presented a high EMI shielding effectiveness (EMI SE) of up to 46 dB against the X band, and ultrahigh specific EMI SE of 271.2 dB mm–1. Moreover, the prepared hydrophobic AgNW/cellulose (H-AgNW/cellulose) composite paper could also maintain high EMI SE and extraordinary waterproofness (water contact angle > 140°) by suffering dozens of bending tests or one thousand peeling tests. Overall, such a multifunctional paper might have practical applications in packaging conductive components and can be used as EMI shielding elements in advanced application areas, even under harsh conditions.

Sign in / Sign up

Export Citation Format

Share Document