scholarly journals Improved Electromagnetic Interference Shielding Properties Through the Use of Segregate Carbon Nanotube Networks

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1395 ◽  
Author(s):  
Sung-Hoon Park ◽  
Ji-Hwan Ha
Keyword(s):  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Electromagnetic Interference ◽  
Silica Particles ◽  
Excluded Volume ◽  
Emi Shielding ◽  
Excluded Volume Effects ◽  
Content Ratio ◽  
Shielding Properties ◽  
Micro Silica

We report the enhanced electromagnetic interference (EMI) shielding properties of hybrid carbon nanotube (CNT) composites consisting of more than two kinds of fillers through the use of segregate conducting networks. An excluded volume was created by micro-sized silica particles that concentrate the CNT network, resulting in improved electrical conductivity and microwave properties. To achieve the optimal dispersion of CNTs and silica particles, high shear force was applied to the pre-cured composite mixture via three-roll milling. Depending on the micro-silica content ratio, we observed improved electrical conductivity and EMI shielding properties. For a quantitative comparison to observe the excluded-volume effects, a CNT composite without micro-silica was measured in parallel with the other sample.

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.

Incorporating a microcellular structure into PVDF/graphene–nanoplatelet composites to tune their electrical conductivity and electromagnetic interference shielding properties

2018 ◽  
Vol 6 (38) ◽  
pp. 10292-10300 ◽  
Author(s):  
Biao Zhao ◽  
Chongxiang Zhao ◽  
Mahdi Hamidinejad ◽  
Chongda Wang ◽  
Ruosong Li ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electromagnetic Interference ◽  
Emi Shielding ◽  
Electromagnetic Interference Shielding ◽  
Graphene Nanoplatelet ◽  
Shielding Properties

The electrical conductivity and the EMI shielding properties could be effectively tuned by the foaming degree.

scholarly journals Electrical Properties and Electromagnetic Interference Shielding Effectiveness of Interlayered Systems Composed by Carbon Nanotube Filled Carbon Nanofiber Mats and Polymer Composites

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 238 ◽  
Author(s):  
Claudia Angélica Ramírez-Herrera ◽  
Homero Gonzalez ◽  
Felipe de la Torre ◽  
Laura Benitez ◽  
José Gerardo Cabañas-Moreno ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Electromagnetic Interference ◽  
Communication Systems ◽  
Carbon Nanofiber ◽  
Layered Composite ◽  
Multiwall Carbon Nanotube ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Nanofiber Composite

The demand for multifunctional requirements in aerospace, military, automobile, sports, and energy applications has encouraged the investigation of new composite materials. This study focuses on the development of multiwall carbon nanotube (MWCNT) filled polypropylene composites and carbon nanofiber composite mats. The developed systems were then used to prepare interlayered composites that exhibited improved electrical conductivity and electromagnetic interference (EMI) shielding efficiency. MWCNT-carbon nanofiber composite mats were developed by centrifugally spinning mixtures of MWCNT suspended in aqueous poly(vinyl alcohol) solutions. The developed nanofibers were then dehydrated under sulfuric acid vapors and then heat treated. Interlayered samples were fabricated using a nanoreinforced polypropylene composite as a matrix and then filled with carbon fiber composite mats. The in-plane and through-plane electrical conductivity of an eight-layered flexible carbon composite (0.65 mm thick) were shown to be 6.1 and 3.0 × 10−2 S·cm−1, respectively. The EMI shielding effectiveness at 900 MHz increased from 17 dB for the one-layered composite to 52 dB for the eight-layered composite. It was found that the reflection of the electromagnetic waves was the dominating mechanism for EMI shielding in the developed materials. This study opens up new opportunities for the fabrication of novel lightweight materials that are to be used in communication systems.

Morphological regulation improved electrical conductivity and electromagnetic interference shielding in poly(l-lactide)/poly(ε-caprolactone)/carbon nanotube nanocomposites via constructing stereocomplex crystallites

2017 ◽  
Vol 5 (11) ◽  
pp. 2807-2817 ◽  
Author(s):  
Kai Zhang ◽  
Hai-Ou Yu ◽  
Yu-Dong Shi ◽  
Yi-Fu Chen ◽  
Jian-Bing Zeng ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Electromagnetic Interference ◽  
Emi Shielding ◽  
Electromagnetic Interference Shielding

Morphological regulation induced by stereocomplex crystallites was used to design PLLA-based composites with enhanced electrical conductivity and EMI shielding.

Size Effect of Particulate Filler on Electrical Resistivity of Carbon Nanotube Polymer Composites: Transition of Excluded Volume Effects

2014 ◽  
Vol 2014 (1) ◽  
pp. 000268-000271
Author(s):  
Sung-Hoon Park ◽  
Jinyoung Hwang ◽  
Dong-Jin Yun ◽  
Sangeui Lee ◽  
Sang Hyun Lee ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electrical Resistivity ◽  
Carbon Nanotube ◽  
Size Effect ◽  
Polymer Composites ◽  
Excluded Volume ◽  
Excluded Volume Effects ◽  
Conductivity Increase ◽  
Particulate Filler ◽  
Volume Effects

Hybrid Carbon nanotube (CNT) composites consisting more than two different kind fillers have received considerable attention which could improve electrical conductivity and mechanical properties. Incorporation of micro-scale second filler, excluded volume is created that effectively creates a segregated network of nanotube. Even if there were successful trials with theoretical model in second filler composite system, it was not fully understood how the electrical conductivity increase with respect to shape (or size) of second filler. Aim of the present research is an understanding of size effect of particulate filler on electrical resistivity of carbon nanotube polymer composites. Depending on size of particulate filler, conductivity of carbon nanotube polymer composites are changed (increase or decrease) indicating there is transition of excluded volume effects. For example, enhanced conductivity was observed in cooperation with micro-size second filler while decreased conductivity was observed for nano-size filler.

scholarly journals Carbon Nanotube versus Graphene Nanoribbon: Impact of Nanofiller Geometry on Electromagnetic Interference Shielding of Polyvinylidene Fluoride Nanocomposites

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1064 ◽  
Author(s):  
Mohammad Arjmand ◽  
Soheil Sadeghi ◽  
Ivonne Otero Navas ◽  
Yalda Zamani Keteklahijani ◽  
Sara Dordanihaghighi ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Electromagnetic Interference ◽  
Polyvinylidene Fluoride ◽  
Network Formation ◽  
Molecular Simulations ◽  
Graphene Nanoribbon ◽  
Emi Shielding ◽  
Pvdf Matrix ◽  
The Impact

The similar molecular structure but different geometries of the carbon nanotube (CNT) and graphene nanoribbon (GNR) create a genuine opportunity to assess the impact of nanofiller geometry (tube vs. ribbon) on the electromagnetic interference (EMI) shielding of polymer nanocomposites. In this regard, GNR and its parent CNT were melt mixed with a polyvinylidene fluoride (PVDF) matrix using a miniature melt mixer at various nanofiller loadings, i.e., 0.3, 0.5, 1.0 and 2.0 wt%, and then compression molded. Molecular simulations showed that CNT would have a better interaction with the PVDF matrix in any configuration. Rheological results validated that CNTs feature a far stronger network (mechanical interlocking) than GNRs. Despite lower powder conductivity and a comparable dispersion state, it was interestingly observed that CNT nanocomposites indicated a highly superior electrical conductivity and EMI shielding at higher nanofiller loadings. For instance, at 2.0 wt%, CNT/PVDF nanocomposites showed an electrical conductivity of 0.77 S·m−1 and an EMI shielding effectiveness of 11.60 dB, which are eight orders of magnitude and twofold higher than their GNR counterparts, respectively. This observation was attributed to their superior conductive network formation and the interlocking ability of the tubular nanostructure to the ribbon-like nanostructure, verified by molecular simulations and rheological assays.

Fire/Heat-Resistant, Anti-Corrosion and Folding Ti2C3Tx MXene/Single-Walled Carbon Nanotube Film for Extreme-Environmental EMI Shielding and Solar-Thermal Conversion Applications

2021 ◽  
Author(s):  
Bing Zhou ◽  
Yanli Li ◽  
Zhaoyang Li ◽  
Jianmin Ma ◽  
Keqing Zhou ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Heat Resistance ◽  
Electromagnetic Interference ◽  
Thermal Conversion ◽  
Solar Thermal ◽  
Emi Shielding ◽  
Single Walled Carbon Nanotube ◽  
Conductive Films ◽  
High Efficient

Polymer-based nacre-like conductive films used in high-efficient electromagnetic interference (EMI) shielding and solar-thermal conversion are often limited by poor fire/heat resistance and unsatisfactory electrical conductivity, which would tremendously impede their...

Electrical conductivity and electromagnetic interference shielding efficiency of carbon nanotube/cellulose composite paper

Carbon ◽  
2008 ◽  
Vol 46 (9) ◽  
pp. 1256-1258 ◽  
Author(s):  
Bunshi Fugetsu ◽  
Eiichi Sano ◽  
Masaki Sunada ◽  
Yuzuru Sambongi ◽  
Takao Shibuya ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Electromagnetic Interference ◽  
Electromagnetic Interference Shielding ◽  
Cellulose Composite ◽  
Composite Paper
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