Morphology Origin of Gradually Weakened Thermal-Conductivity Enhancement for HDPE/MWCNTs Nanocomposites

2016 ◽  
Author(s):  
Xiao-Hong Yin ◽  
Can Yang ◽  
Shiju E ◽  
Xiping Li ◽  
Jianbo Cao
Keyword(s):  
Thermal Conductivity ◽  
Phonon Scattering ◽  
Loss Modulus ◽  
Low Frequency ◽  
Complex Viscosity ◽  
Thermal Conductivity Enhancement ◽  
Mwcnt Content ◽  
Conductivity Enhancement ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

In this work, high-density polyethylene/multi-walled carbon nanotubes (HDPE/MWCNTs) nanocomposites containing various filler loadings (i.e., 0.5∼16.0 wt.%) were prepared with their thermal conductivities determined using a laser-based analyzer. It was found that although the nanocomposite’s thermal conductivity increased with elevated MWCNT content, the enhancement degree lowered gradually. Rheology and microstructure characterizations were performed to reveal the morphology origin of gradually weakened thermal-conductivity enhancement. The dynamic rheology measurements showed that all nanocomposites exhibited higher storage modulus (G′), loss modulus (G″) as well as complex viscosity (η*) compared with the neat HDPE. More interestingly, the plateau of the flow regime formed at low frequency ranges with MWCNT loadings higher than 2.0 wt.% suggested the formation of the MWNCT network structures within the nanocomposites. The existence of such structures was further verified by the Cole-Cole curves obtained from the rheology testing and MWCNT distribution states from scanning electron microscope (SEM) results. The formation of MWCNT network lowered the degree of thermal-conductivity enhancement in such a way that it gave a larger possibility for MWCNTs to agglomerate, which led to phonon scattering that reduced the nanocomposite’s thermal conductivity.

Thermal Conductivity Measurement for Carbon-Nanotube Suspensions with 3ω Method

2009 ◽  
Vol 60-61 ◽  
pp. 394-398 ◽  
Author(s):  
Gen Sheng Wu ◽  
Jue Kuan Yang ◽  
Shu Lin Ge ◽  
Yu Juan Wang ◽  
Min Hua Chen ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Volume Fraction ◽  
Aqueous Suspension ◽  
Conductivity Measurement ◽  
3Ω Method ◽  
Conductivity Enhancement ◽  
Multi Walled Carbon Nanotubes ◽  
The Stability ◽  
Walled Carbon Nanotubes

The stable and homogeneneous aqueous suspension of carbon nanotubes was prepared in this study. The stability of the nanofluids was improved greatly due to the use of a new dispersant, humic acid. The thermal conductivity of the aqueous suspension was measured with the 3ω method. The experimental results showed that the thermal conductivity of the suspensions increases with the temperature and also is nearly proportional to the loading of the nanoparticles. The thermal conductivity enhancement of single-walled carbon nanotubes (SWNTs) suspensions is better than that of the multi-walled carbon nanotubes (MWNTs) suspensions. Especially for a volume fraction of 0.3846% SWNTs, the thermal conductivity is enhanced by 40.5%. Furthermore, the results at 30°C match well with Jang and Choi’s model.

scholarly journals Thermophysical Properties of IoNanofluids Composed of 1-ethyl-3-methylimidazolium Thiocyanate and Carboxyl-functionalized Long Multi-walled Carbon Nanotubes

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 214
Author(s):  
Bertrand Jóźwiak ◽  
Justyna Dziadosz ◽  
Adrian Golba ◽  
Krzysztof Cwynar ◽  
Grzegorz Dzido ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Carboxylic Group ◽  
Conductivity Enhancement ◽  
Multi Walled Carbon Nanotubes ◽  
Vibrating Tube Densimeter ◽  
Carbon Based Nanomaterials ◽  
Walled Carbon Nanotubes ◽  
Rotary Viscometer

The concept of IoNanofluids (INFs) as the stable dispersions of nanoparticles in ionic liquids was proposed in 2009 by Nieto de Castro’s group. INFs characterize exciting properties such as improved thermal conductivity, non-volatility, and non-flammability. This work is a continuation of our studies on the morphology and physicochemistry of carbon-based nanomaterials affecting thermal conductivity, viscosity, and density of INFs. We focus on the characterization of dispersions composed of long carboxylic group-functionalized multi-walled carbon nanotubes and 1-ethyl-3-methylimidazolium thiocyanate. The thermal conductivity of INFs was measured using KD2 Pro Thermal Properties Analyzer (Decagon Devices Inc., Pullman, WA, USA). The viscosity was investigated using rotary viscometer LV DV-II+Pro (Brookfield Engineering, Middleboro, MA, USA). The density of INFs was measured using a vibrating tube densimeter Anton Paar DMA 5000 (Graz, Austria). The maximum thermal conductivity enhancement of 22% was observed for INF composed of 1 wt% long carboxylic group-functionalized multi-walled carbon nanotubes.

scholarly journals Thermophysical Properties of Nanofluids Composed of Ethylene Glycol and Long Multi-Walled Carbon Nanotubes

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 241
Author(s):  
Karolina Brzóska ◽  
Bertrand Jóźwiak ◽  
Adrian Golba ◽  
Marzena Dzida ◽  
Sławomir Boncel
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Ethylene Glycol ◽  
Chemical Vapor ◽  
Step Method ◽  
Mwcnt Content ◽  
Multi Walled Carbon Nanotubes ◽  
The Stability ◽  
Walled Carbon Nanotubes ◽  
Rotary Viscometer

In this work, thermal conductivity, viscosity, isobaric heat capacity, and density of stable carbon-based nanofluids are presented. The nanofluids under study are composed of 1,2-ethanediol (ethylene glycol, EG) and long multi-walled carbon nanotubes (MWCNTs), so-called ‘in-house 16h’ (synthesized in our laboratory via catalytic chemical vapor deposition during 16 h with a diameter of 60–80 nm and length of 770 μm). Poly(N-vinylpyrrolidone) (PVP) was used to increase the stability of nanofluids. The nanofluids were prepared via an ultrasonication-assisted, three-step method while their key thermophysical characteristics were obtained using the hot-wire technique and rotary viscometer. As a result, the addition of MWCNTs significantly improved the thermal conductivity of nanofluids by 31.5% for the highest 1.0 wt% (0.498 vol%) long MWCNT content, leaving the Newtonian character of the nanofluids practically intact.

Water Based Multiwalled Carbon Nanotube Nanofluids With Optimized Thermal Conductivity

2009 ◽  
Author(s):  
Li Fei Chen ◽  
Huaqing Xie ◽  
Wei Yu ◽  
Yang Li
Keyword(s):  
Thermal Conductivity ◽  
Ball Milling ◽  
Volume Fraction ◽  
Free Water ◽  
Strong Acid ◽  
Multiwalled Carbon ◽  
Conductivity Enhancement ◽  
Water Based ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

We report a method to prepare surfactant-free water based nanofluids containing multi-walled carbon nanotubes (CNTs). The as prepared CNTs with hard dispersibility, after being cut by mechanical ball-milling approach following strong acid treatment, can be directly dispersed into water. The thermal conductivity of the nanofluids is optimized by controlling the CNT length and straightness. It is realized by changed the ball-milling times. The thermal conductivity enhancement of water based CNT nanofluids with volume fraction of 1% attains 29.5% by controlling the CNT length and straightness when the temperature is 63.9°C.

Enhanced Thermal Conductivity of Nanofluid by Synergistic Effect of Multi-Walled Carbon Nanotubes and Fe2O3 Nanoparticles

2014 ◽  
Vol 548-549 ◽  
pp. 118-123 ◽  
Author(s):  
Li Fei Chen ◽  
Min Cheng ◽  
De Jun Yang ◽  
Lei Yang
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Synergistic Effect ◽  
Interfacial Adhesion ◽  
Conductivity Enhancement ◽  
Hybrid Fillers ◽  
Water Based ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Enhanced Thermal Conductivity

This study investigates the synergistic effect of combining multi-walled carbon nanotubes (MWNTs) and Fe2O3nanoparticles on thermal conductivity of nanofluid. Results show that low percentage hybrid fillers loading improve thermal conductivity of water based nanofluid, due to the good dispersion and interfacial adhesion, which is confirmed by scanning electron microscope. Furthermore, the hybrid fillers provide synergistic effect on heat conductive networks. The thermal conductivity enhancement of water based nanofluid containing 0.05 wt % MWNTs and 0.02 wt % Fe2O3nanoparticles is 27.75%, which is higher than that of nanofluid containing 0.2 wt % single MWNTs or Fe2O3nanoparticles.

Rheological Behaviors of Carbonaceous Materials Suspended in Sodium Alginate Solutions

2014 ◽  
Vol 906 ◽  
pp. 232-237 ◽  
Author(s):  
Hai Xiang Liu ◽  
Ye Qiang Tan ◽  
Qing Xu Zhang ◽  
Xue Qin ◽  
Ran Ran Zheng ◽  
...  
Keyword(s):  
Sodium Alginate ◽  
Loss Modulus ◽  
Chemical Properties ◽  
Complex Viscosity ◽  
Carbonaceous Materials ◽  
Rheological Measurement ◽  
Rheological Behaviors ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
And Chemical Properties

Three kinds of carbonaceous materials with different structural and chemical properties, Carbon Black (CB), Multi-walled Carbon Nanotubes (MWNTs), and Graphene Oxide (GO), were well suspended in sodium alginate (SA) solutions, and the suspension rheological behaviors were investigated in details. Steady rheological results showed that the suspensions exhibited same shear-thinning behaviors as SA solution. Dynamic rheological results showed that the complex viscosity (η*) was similar to that of steady rheological measurement, and both SA solution and SA/carbonaceous materials suspensions exhibited liquid-like behaviors, confirmed by the loss modulus larger than the storage modulus. The loss factor tanδremarkably decreased for SA/GO solution compared with SA/CB and SA/MWNTs suspension at the same concentration, indicating the increase of elasticity via interactions between the GO and SA.

THERMAL CONDUCTIVITY ENHANCEMENT OF MATERIAL FOR CALCIUM CHLORIDE/WATER THERMOCHEMICAL ENERGY STORAGE

2018 ◽  
Author(s):  
Takuma Ohtaki ◽  
Maho Mitsuo ◽  
Takayuki Terauchi ◽  
Hiroshi Iguchi ◽  
Keiko Fujioka ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Calcium Chloride ◽  
Thermal Conductivity Enhancement ◽  
Conductivity Enhancement ◽  
Chloride Water
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