Effects of branched carbon nanotubes and graphene nanoplatelets on dielectric properties of thermoplastic polyurethane at different temperatures

The dielectric properties of epoxy/MWCNT (multi-walled carbon nanotubes)/MgO hybrid composites with a fixed MWCNT amount of 0.12 vol.% (0.2 wt.%) and varying MgO concentrations up to 3 vol.% were investigated in broad frequency (20–40 GHz) and temperature (20–500 K) ranges. The composites with up to 2 vol.% MgO nanoparticles concentration showed a significant increase of DC conductivity in relation to their non MgO-containing counterparts. The optimal content of MgO was found, i.e., 0.46 vol.%, which gave up to 2.5 orders of magnitude larger DC conductivity than those of the samples prepared without MgO additives. Using various amounts of MgO, it is possible to predictably vary the broadband electromagnetic properties of the composites, even entirely eliminating the electrical percolation. Electrical transport at different temperatures can be substantially controlled by the addition of given amounts of MgO. The broadband properties are discussed in terms of the distribution of relaxation times, which are proven to be an effective, noninvasive, and simple tool for checking composite fabrication issues, such as the distribution of MWCNT aggregates within the epoxy matrix.

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Improving flexural and dielectric properties of carbon fiber epoxy composite laminates reinforced with carbon nanotubes interlayer using electrospray deposition

Nanotechnology Reviews ◽

10.1515/ntrev-2020-0090 ◽

2020 ◽

Vol 9 (1) ◽

pp. 1170-1182

Author(s):

Muhammad Razlan Zakaria ◽

Hazizan Md Akil ◽

Mohd Firdaus Omar ◽

Mohd Mustafa Al Bakri Abdullah ◽

Aslina Anjang Ab Rahman ◽

...

Keyword(s):

Carbon Nanotubes ◽

Dielectric Properties ◽

Carbon Fiber ◽

Composite Laminates ◽

Epoxy Composite ◽

Flexural Modulus ◽

X Ray Diffraction ◽

Electrospray Deposition ◽

Ft Ir ◽

Carbon Fiber Epoxy

AbstractThe electrospray deposition method was used to deposit carbon nanotubes (CNT) onto the surfaces of woven carbon fiber (CF) to produce woven hybrid carbon fiber–carbon nanotubes (CF–CNT). Extreme high-resolution field emission scanning electron microscopy (XHR-FESEM), X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR) were used to analyze the woven hybrid CF–CNT. The results demonstrated that CNT was successfully and homogenously distributed on the woven CF surface. Woven hybrid CF–CNT epoxy composite laminates were then prepared and compared with woven CF epoxy composite laminates in terms of their flexural and dielectric properties. The results indicated that the flexural strength, flexural modulus and dielectric constant of the woven hybrid CF–CNT epoxy composite laminates were improved up to 19, 27 and 25%, respectively, compared with the woven CF epoxy composite laminates.

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Investigation of Dielectric Properties of TiO2 and Al2O3 nanofluids by Frequency Domain Spectroscopy at Different Temperatures

Journal of Molecular Liquids ◽

10.1016/j.molliq.2021.115642 ◽

2021 ◽

Vol 330 ◽

pp. 115642

Author(s):

B. Chakraborty ◽

K.Y. Raj ◽

A.K. Pradhan ◽

B. Chatterjee ◽

S. Chakravorti ◽

...

Keyword(s):

Dielectric Properties ◽

Frequency Domain ◽

Different Temperatures

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Solvent-free process for the synthesis of highly stretchable piezoresistive sensors based on polydimethylsiloxane filled with graphene nanoplatelets and carbon nanotubes

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1024/1/012003 ◽

2021 ◽

Vol 1024 (1) ◽

pp. 012003

Author(s):

F. Piscitelli ◽

M. L. Lo Gatto ◽

G. Rollo ◽

G. Filippone ◽

M. Lavorgna

Keyword(s):

Carbon Nanotubes ◽

Graphene Nanoplatelets ◽

Solvent Free ◽

Piezoresistive Sensors ◽

Free Process ◽

Highly Stretchable

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Kinetics and thermodynamics of the sorption of furaltadone from aqueous solutions on magnetic multi-walled carbon nanotubes

Water Science & Technology ◽

10.2166/wst.2014.313 ◽

2014 ◽

Vol 70 (6) ◽

pp. 964-971

Author(s):

Xu Chen ◽

Zhen-hu Xiong

Keyword(s):

Carbon Nanotubes ◽

Aqueous Solutions ◽

Sorption Data ◽

Multi Wall Carbon Nanotubes ◽

Adsorption Behaviors ◽

Different Temperatures ◽

Multi Walled Carbon Nanotubes ◽

Pseudo Second Order ◽

Experimental Data Analysis ◽

Walled Carbon Nanotubes

Magnetic multi-wall carbon nanotubes (M-MWCNTs) were used as an adsorbent for removal of furaltadone from aqueous solutions, and the adsorption behaviors were investigated by varying pH, sorbent amount, sorption time and temperature. The results showed that the adsorption efficiency of furaltadone reached 97% when the dosage of M-MWCNT was 0.45 g · L−1, the pH was 7 and the adsorption time was 150 min. The kinetic data showed that the pseudo-second-order model can fit the adsorption kinetics. The sorption data could be well explained by the Langmuir model under different temperatures. The adsorption process was influenced by both intraparticle diffusion and external mass transfer. The experimental data analysis indicated that the electrostatic attraction and π–π stacking interactions between M-MWCNT and furaltadone might be the adsorption mechanism. Thermodynamic analysis reflected that adsorption of furaltadone on the M-MWCNT was spontaneous and exothermic. Our study showed that M-MWCNTs can be used as a potential adsorbent for removal of furaltadone from water and wastewater.

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Temperature-Dependent Synergistic Effect of Multi-Walled Carbon Nanotubes and Graphene Nanoplatelets on the Tensile Quasi-Static and Fatigue Properties of Epoxy Nanocomposites

Polymers ◽

10.3390/polym13010084 ◽

2020 ◽

Vol 13 (1) ◽

pp. 84

Author(s):

Yi-Ming Jen ◽

Hao-Huai Chang ◽

Chien-Min Lu ◽

Shin-Yu Liang

Keyword(s):

Carbon Nanotubes ◽

Fatigue Strength ◽

Synergistic Effect ◽

Polymer Nanocomposites ◽

Graphene Nanoplatelets ◽

Temperature Dependent ◽

Epoxy Nanocomposites ◽

Hybrid Fillers ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

Even though the characteristics of polymer materials are sensitive to temperature, the mechanical properties of polymer nanocomposites have rarely been studied before, especially for the fatigue behavior of hybrid polymer nanocomposites. Hence, the tensile quasi-static and fatigue tests for the epoxy nanocomposites reinforced with multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) were performed at different temperatures in the study to investigate the temperature-dependent synergistic effect of hybrid nano-fillers on the studied properties. The temperature and the filler ratio were the main variables considered in the experimental program. A synergistic index was employed to quantify and evaluate the synergistic effect of hybrid fillers on the studied properties. Experimental results show that both the monotonic and fatigue strength decrease with increasing temperature significantly. The nanocomposites with a MWCNT (multi-walled CNT): GNP ratio of 9:1 display higher monotonic modulus/strength and fatigue strength than those with other filler ratios. The tensile strengths of the nanocomposite specimens with a MWCNT:GNP ratio of 9:1 are 10.0, 5.5, 12.9, 23.4, and 58.9% higher than those of neat epoxy at −28, 2, 22, 52, and 82 °C, respectively. The endurance limits of the nanocomposites with this specific filler ratio are increased by 7.7, 26.7, 5.6, 30.6, and 42.4% from those of pristine epoxy under the identical temperature conditions, respectively. Furthermore, the synergistic effect for this optimal nanocomposite increases with temperature. The CNTs bridge the adjacent GNPs to constitute the 3-D network of nano-filler and prevent the agglomeration of GNPs, further improve the studied strength. Observing the fracture surfaces reveals that crack deflect effect and the bridging effect of nano-fillers are the main reinforcement mechanisms to improve the studied properties. The pullout of nano-fillers from polymer matrix at high temperatures reduces the monotonic and fatigue strengths. However, high temperature is beneficial to the synergistic effect of hybrid fillers because the nano-fillers dispersed in the softened matrix are easy to align toward the directions favorable to load transfer.

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Dielectric properties of Shell oil transformer oil with impurities of carbon nanotubes and fullerene C60

Semiconductor Physics Quantum Electronics & Optoelectronics ◽

10.15407/spqeo24.04.413 ◽

2021 ◽

Vol 24 (04) ◽

pp. 413-418

Author(s):

O.V. Kovalchuk ◽

◽

I.P. Studenyak ◽

T.M. Kovalchuk ◽

E.A. Ayryan ◽

...

Keyword(s):

Magnetic Field ◽

Carbon Nanotubes ◽

Electrical Conductivity ◽

Dielectric Properties ◽

Fullerene C60 ◽

Transformer Oil ◽

C60 Fullerene ◽

Cooling Efficiency ◽

Fullerene Concentration ◽

Multiwall Nanotubes

At the temperature 293 K, the influence of two types of nanoimpurities (carbon multiwall nanotubes and C60 fullerene) both separately and together on the dielectric properties of Shell oil transformer oil has been studied. It has been shown that these impurities do not significantly effect on the value of the dielectric permittivity of Shell oil, but more significantly increase its conductivity. It has been found that in the presence of nanotubes inside Shell oil, the dependence of its electrical conductivity on the fullerene concentration is nonmonotonic. The samples with the fullerene concentration 100 ppm have the highest conductivity. At the fullerene concentration 300 ppm, the conductivity of Shell oil with the impurities of carbon nanotube and C60 fullerene becomes almost equal to the electrical conductivity of Shell oil only with the impurities of carbon nanotubes. It has been suggested that C60 fullerene can be used to reduce the electrical conductivity of Shell oil with magnetic nanoparticles required to increase the cooling efficiency of transformers under the action of their own magnetic field.

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