Microwave Properties of Nanocomposites: Effect of Manufacturing Methods and Nanofiller Structure

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
A. A. Khurram ◽  
Sobia A. Rakha ◽  
Naveed Ali ◽  
I. H. Gul ◽  
Arshad Munir
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Return Loss ◽  
Epoxy Composite ◽  
Multiwall Carbon Nanotubes ◽  
Frequency Range ◽  
Epoxy Nanocomposite ◽  
Surface Functionality ◽  
Dc Electrical Conductivity ◽  
Multiwall Carbon

Nanocomposite materials filled with multiwall carbon nanotubes (MWCNTs) having three types of structures, i.e., longer (200 μm), shorter (20–50 μm), and aminated (20–50 μm), are manufactured for microwave absorption (MA) in 11–17 GHz frequency range. Microstructure, dielectric permittivity, direct current (DC) electrical conductivity, and MA properties of the MWCNTs–epoxy nanocomposite were investigated. A correlation has been developed between the structure (aspect ratio and surface functionality) of MWCNTs, electrical conductivity of the composite, and MA (return loss (RL)). E-glass/epoxy composite filled with longer carbon nanotubes (CNTs) has shown higher RL as compared to that of other two nanocomposites. The measurements have shown that the magnitude of RL of microwaves depends strongly on the structure of MWCNTs used in the composite. Furthermore, the effect of synthesis route followed for the manufacturing of nanocomposite on its electrical conductivity and microwave absorbing properties is also investigated; three different approaches were followed to manufacture CNT/epoxy nanocomposites from longer CNTs (200 μm).

Control of multiwall carbon nanotubes dispersion in polyamide6 matrix: An assessment through electrical conductivity

2006 ◽  
Vol 432 (4-6) ◽  
pp. 480-485 ◽  
Author(s):  
Pravin V. Kodgire ◽  
Arup R. Bhattacharyya ◽  
Suryasarathi Bose ◽  
Nitin Gupta ◽  
Ajit R. Kulkarni ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Multiwall Carbon Nanotubes ◽  
Multiwall Carbon

Simultaneous enhancement in mechanical strength, electrical conductivity, and electromagnetic shielding properties in PVDF–ABS blends containing PMMA wrapped multiwall carbon nanotubes

2015 ◽  
Vol 17 (22) ◽  
pp. 14856-14865 ◽  
Author(s):  
Goutam Prasanna Kar ◽  
Sourav Biswas ◽  
Suryasarathi Bose
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Mechanical Strength ◽  
Multiwall Carbon Nanotubes ◽  
Electromagnetic Shielding ◽  
Unique Approach ◽  
Shielding Properties ◽  
Multiwall Carbon

A unique approach was adopted to drive the multiwall carbon nanotubes (MWNTs) to the interface of immiscible PVDF–ABS blends by wrapping the nanotubes with a mutually miscible homopolymer (PMMA).

scholarly journals Fabrication of Metal Alloy-Deposited Flexible MWCNT Buckypaper for Thermoelectric Applications

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Jih-Hsin Liu ◽  
Hsin-Yuan Miao ◽  
Saravanan Lakshmanan ◽  
Li-Chih Wang ◽  
Ren-Hui Tsai
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermal Evaporation ◽  
Multiwall Carbon Nanotubes ◽  
Metal Alloys ◽  
Thermal Evaporation Method ◽  
In Series ◽  
Multiwall Carbon ◽  
Temperature Resistivity

We report the fabrication of a flexible network of multiwall carbon nanotubes (MWCNTs) known as buckypaper (BP) for thermoelectric (TE) applications. A thermal evaporation method was used to deposit TE metal alloys onto the BP. The TE properties were improved primarily by increasing the Seebeck coefficient values (50 and 75 μV/K) and the electrical conductivity by approximately 10 000 S/m. High-temperature resistivity studies were performed to confirm the semiconductivity of buckypaper. Variations in resistivity were observed to be the result of the metal alloys coated on the BP surface. We also demonstrated that a substantial increase in the Seebeck coefficient values can be obtained by connecting 3 and 5 layers of metal-deposited BP in series, thereby enhancing the TE efficiency of MWCNT-based BP for application in thermoelectric devices.

Light Reflectivity of Multiwall Carbon Nanotubes with Pattern-Less or Pattern-Grown Nanotubes

2013 ◽  
Vol 284-287 ◽  
pp. 429-433
Author(s):  
Yun Hsih Chou ◽  
Yih Guang Jan ◽  
Liang Yu Yen ◽  
Chao Chung Huang ◽  
Chuan Ping Juan ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Wavelength Range ◽  
Return Loss ◽  
Multiwall Carbon Nanotubes ◽  
Black Body ◽  
High Density ◽  
Absorption Effect ◽  
Multiwall Carbon ◽  
High Absorption

The light reflectivity of multiwall carbon nanotubes (MWCNTs) in the 1150nm - 1755 nm wavelength range with pattern-less and pattern-grown nanotubes are studied. From test measurements it concludes that when the multiwall carbon nanotubes are pattern-grown fabricated its return loss is linearly proportional to the nanotubes grown height and consequently the pattern-grown CNTs can be implemented as a good optical attenuator. However for high density nanotubes fabricated with pattern-less process it has greater than 45 dB return loss, this is equivalent to have less than 0.56% reflectivity; with this high absorption effect it can be utilized as a black body absorber.

scholarly journals Incorporation of Functionalized Multiwall Carbon Nanotubes into a Polyurethane Matrix

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Martin Michálek ◽  
Michael Bredol
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Percolation Threshold ◽  
Aqueous Suspension ◽  
Sodium Dodecyl ◽  
Multiwall Carbon Nanotubes ◽  
Glass Substrates ◽  
Functionalized Mwcnts ◽  
Multiwall Carbon

Functionalized and raw multiwall carbon nanotubes (MWCNTs) were investigated colloid-chemically in order to study the role of polar versus nonpolar interaction with a polyurethane (PU) matrix. Both kinds of MWCNTs were dispersed by ultrasonication in the presence of a surfactant (sodium dodecyl sulphate) in aqueous solution. Functional groups on the nanotube surface were characterized by infrared spectroscopy and by theζ-potential in aqueous suspension. Such suspensions were added to waterborne PU dispersions, drop-cast on glass substrates and cured. The percolation threshold for electrical conductivity with polar (functionalized) MWCNTs was reached at 0.24 wt.%, whereas at concentrations as high as 2 wt.%, PU films with nonpolar MWCNTs stayed below the percolation threshold. With an addition of 0.4 wt.% polar MWCNTs, the electrical conductivity increased to >10−6 S/cm in the cured coating layer. These results are interpreted with respect to the chemical nature of the PU matrix.

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