Current progress on the modification of carbon nanotubes and their application in electromagnetic wave absorption

Fu-tian, Ren; Yu, Haipeng; Wang, Li; Saleem, Muhammad; Tian, Zhifei; Ren, Pengfei

doi:10.1039/c3ra46989a

Cited by 129 publications

(71 citation statements)

References 148 publications

(138 reference statements)

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“…For the s-CNT/PE composite with a segregated structure, the majority of CNTs participate in building conductive pathways, and they can contact and overlap more frequently, thus leading to perfect conductive networks. 18,41,53,54 Especially for the composites with randomly distributed CNT, reflection is the primary mechanism and absorption is secondary, 55 while the multiple reflection is usually ignored as an EMI SE higher than 10 dB. While for the r-CNT/PE composite with randomly distributed CNT in the whole system, abundant CNTs are separated from others, having no any contribution to formation of conductive networks, giving rise to the weakest conductivity.…”

Section: Electrical Conductivitymentioning

confidence: 99%

Electrically conductive and electromagnetic interference shielding of polyethylene composites with devisable carbon nanotube networks

et al. 2015

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This paper reports a comparative study on the electrical and electromagnetic interference (EMI) shielding performance of three carbon nanotube/polyethylene (CNT/PE) composites with different conductive networks, i.e., segregated structure (s-CNT/PE), partially segregated structure (p-CNT/PE) and randomly distributed structure (r-CNT/PE). The s-CNT/PE composite exhibits superior electrical conductivity up to 2 orders of magnitude over that of p-CNT/PE and r-CNT/PE composites, at the same CNT loading. Only 5 wt% CNT addition in the s-CNT/PE composite realizes an excellent EMI shielding effectiveness (SE) as high as 46.4 dB, which is 20% and 46% higher than that for p-CNT/PE and r-CNT/PE composites, respectively. The selectively distributed CNT at the interfaces between PE polyhedrons would certainly increase the effective CNT concentrations that form conducting pathways and thus increase the electrical conductivity and EMI SE in the s-CNT/PE composite. Such special structure also provides numerous interfaces that absorb the electromagnetic waves, resulting in an absorption-dominated shielding mechanism. Our work suggests that designing the conductive network in polymer composites is a promising approach to develop high-performance EMI shielding materials.

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Section: Electrical Conductivitymentioning

confidence: 99%

Electrically conductive and electromagnetic interference shielding of polyethylene composites with devisable carbon nanotube networks

et al. 2015

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“…Controlled microstructural heterogeneities in the composites are key for a macroscale absorption response. In general, EM radiation encounters variety of macroscopic boundaries due to the direct interaction between the composite and incident EM radiation . As discussed earlier, the total EM shield effectiveness (SE T ) is the combination of shielding by absorption (SE A ), by reflection (SE R ), and by multiple reflection (SE MR ) .…”

Section: Resultsmentioning

confidence: 99%

Simultaneous Improvement in Structural Properties and Microwave Shielding of Polymer Blends with Carbon Nanotubes

2015

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Precisec ontrol in dispersing nanostructured materials in ap olymer blend structure is ak ey requirement in designing materials with tailor-made properties. In this study, the dispersion of ac onducting additive (multiwalledc arbon nanotubes, MWNTs) in ac o-continuous polymer blend structure was controlled by introducing surface-active groups, which react in situ and localize in the thermodynamically nonpreferred phase. In addition, by modifying the MWNTs with am acromolecule, which is mutuallym iscible with the entities, the nanoscopic particles can be localized at the interface. This way,d ifferent MWNTs can be positioned in different phases under macroscopic processingc onditions. Herein, we report that this unique strategy has led to simultaneous enhancement in both mechanical strength and electrical conductivity of the blend nanocomposites. In addition, intriguingly,t he microwave shielding efficiency can also be tuned by this ordered arrangement of MWNTs in the blend structure in strikingc ontrast to when the MWNTsa re in the thermodynamically favored phase. An outstanding two-fold enhancement in the Young'sm odulus, as comparedt oc ontrol blends,a nd an impressive bulk electrical conductivity of 1Sm À1 was noted for ap articular blend structure wherein different MWNTs were positioned in different phases. In addition, the best blend structure designed here also exhibited am inimum reflection loss (R L )o fa pproximately À61 dB and as hielding effectiveness of > 30 dB at 18 GHz. These data uncover the importance of polymer blends in designing lightweight electromagnetic interference (EMI) shielding materials.

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“…The total SE measurements also showed a similar observation in accordance with the conductivity data. 38 The total SE values of various blend compositions analyzed are given in Table 2. 5b) is almost unaltered upon annealing, whereas, a signicant change was observed in the case of 70/30 PS/PVME blends, (Fig.…”

Section: Shielding Effectivenessmentioning

confidence: 99%

Electromagnetic shielding materials and coatings derived from gelation of multiwall carbon nanotubes in an LCST mixture

Xavier

Bose

2014

RSC Adv.

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Thermally induced demixing in an LCST mixture, polystyrene (PS)/poly[vinyl methyl ether] (PVME), was used as a template to design materials with high electrical conductivity. This was facilitated by gelation of multiwall carbon nanotubes (MWNTs) in a given phase of the blends. The MWNTs were mixed in the miscible blends and the thermodynamic driven demixing further resulted in selective localization in the PVME phase of the blends. This was further confirmed by atomic force microscopy (AFM). The time dependent gelation of MWNTs at shallow quench depth, evaluated using isochronal temperature sweep by rheology, was studied by monitoring the melt electrical conductivity of the samples in situ by an LCR meter coupled to a rheometer. By varying the composition in the mixture, several intricate shapes like gaskets and also coatings capable of attenuating the EM radiation in the microwave frequency can be derived. For instance, the PVME rich mixtures can be molded in the form of a gasket, O-ring and other intricate shapes while the PS rich mixtures can be coated onto an insulating polymer to enhance the shielding effectiveness (SE) for EM radiation. The SE of the various materials was analyzed using a vector network analyzer in both the X-band (8.2 to 12 GHz) and the K u -band (12 to 18 GHz) frequency. The improved SE upon gelation of MWNTs in the demixed blends is well evident by comparing the SE before and after demixing. A reflection loss of À35 dB was observed in the blends with 2 wt% MWNTs. Further, by coating a layer of ca. 0.15 mm of PS/PVME/MWNT, a SE of À15 dB at 18 GHz could be obtained.

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Current progress on the modification of carbon nanotubes and their application in electromagnetic wave absorption

Cited by 129 publications

References 148 publications

Electrically conductive and electromagnetic interference shielding of polyethylene composites with devisable carbon nanotube networks

Electrically conductive and electromagnetic interference shielding of polyethylene composites with devisable carbon nanotube networks

Simultaneous Improvement in Structural Properties and Microwave Shielding of Polymer Blends with Carbon Nanotubes

Electromagnetic shielding materials and coatings derived from gelation of multiwall carbon nanotubes in an LCST mixture

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