scholarly journals Preparation and Rheological Properties of Amide-based Multiwalled Carbon Nanotube Mirabilite Phase Change Materials

2021 ◽  
Vol 3 (2) ◽  
pp. 86-91
Author(s):  
Yu Zhang ◽  
Shengnian Tie
Keyword(s):  
Composite Material ◽  
Carbon Nanotube ◽  
Phase Change ◽  
Phase Change Materials ◽  
Volume Fraction ◽  
Temperature Fluctuations ◽  
Multiwalled Carbon Nanotube ◽  
Multiwalled Carbon ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The multi-walled carbon nanotubes (MWCNTs) are modified by redox methods, and the surface groups of the MWCNTs are analyzed by infrared spectroscopy. And the modified MWCNTs were added to the mirabilite-based phase change materials (PCMs) at 40°C to prepare the mirabilite-based phase change composite material. The results show that when the volume fraction is 0.05% and 0.25%, when the temperature rises from 30°C to 50°C, the viscosity drop of the phase change composite material is 35.86% and 37.50%, respectively. That is, the larger the volume of the fraction of nanoparticles, the higher the viscosity, thus the greater the ability to perceive temperature fluctuations. In addition, the amide multiwalled carbon nanotube mirabilite PCMs was placed for 30 days, and the dispersion stability was good, and no phase delamination occurred.

Effect of Expanded Temperature on Microstructure of Carbon Nanotubes/Expanded Graphite Composites

2013 ◽  
Vol 716 ◽  
pp. 373-378
Author(s):  
Qian Zhang ◽  
Xin Bao Gao ◽  
Tian Peng Li
Keyword(s):  
Carbon Nanotubes ◽  
Composite Material ◽  
High Temperature ◽  
Carbon Nanotube ◽  
Physical Adsorption ◽  
Expanded Graphite ◽  
Graphite Flake ◽  
Graphite Composite ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Carbon nanotube/expanded graphite composite material was prepared by expanding the mixture of multi-walled carbon nanotubes and expansible graphite under the condition of high temperature. The microstructure and composition was studied by using SEM and XRD. The study shows that the tubular structure of carbon nanotubes in the composite material is changed by high temperature expanding process, and the microstructure is different with different expanding temperature. When the expanding temperature was 900°C, carbon nanotubes transformed, then attached to the surface of expanded graphite flake, so carbon nanotubes and expanding graphite combined strongly; globular carbon nanotubes attached to the surface of expanded graphite flake at the temperature of 700°C, both were combined much more strongly; carbon nanotubes retained the tube structure at the temperature of 500°C, combination was looser due to the simple physical adsorption. The result shows that the choice of expanding temperature has an important effect on microstructure of carbon nanotube/expanded graphite composite material.

Improving thermal conductivity and decreasing supercooling of paraffin phase change materials by n-octadecylamine-functionalized multi-walled carbon nanotubes

RSC Advances ◽  
2014 ◽  
Vol 4 (69) ◽  
pp. 36584-36590 ◽  
Author(s):  
Qianqiu Tang ◽  
Jun Sun ◽  
Shuangmin Yu ◽  
Gengchao Wang
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Phase Change ◽  
Phase Change Materials ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

N-Octadecylamine-functionalized multi-walled carbon nanotubes (f-MWCNTs) are introduced to paraffin to improve the thermal conductivity and decrease supercooling of phase change materials.

scholarly journals High-Performance Thermal Management Nanocomposites: Silver Functionalized Graphene Nanosheets and Multiwalled Carbon Nanotube

2018 ◽  
Author(s):  
Yongcun Zhou ◽  
Xiao Zhuang ◽  
Feixiang Wu ◽  
Feng Liu
Keyword(s):  
Carbon Nanotube ◽  
Thermal Management ◽  
High Performance ◽  
Volume Fraction ◽  
Graphene Nanosheets ◽  
Multiwalled Carbon Nanotube ◽  
Interfacial Structure ◽  
Processing Unit ◽  
Functionalized Graphene ◽  
Multiwalled Carbon

Silver functionalized graphene nanosheets (GNS) and multiwalled carbon nanotube (MWCNT) composites with excellent thermal properties were developed to meet the requirements of thermal management. The effects of composites on interfacial structure and properties of the composites were identified, and the microstructures and properties of the composites were studied as a function of the volume fraction of fillers. An ultrahigh thermal conductivity of 12.3 W/mK for polymer matrix composites was obtained, which is an approximate enhancement by 69.1 times compared with that of the polyvinyl alcohol (PVA) matrix. Moreover, these composites showed more competitive thermal conductivities compared with those of untreated fillers/PVA composites applied to the desktop central processing unit, making these composites a high-performance alternative to be used for thermal management.

Analysis of Visible Radiative Properties of Vertically Aligned Multi-Walled Carbon Nanotubes

2010 ◽  
Author(s):  
Hua Bao ◽  
Xiulin Ruan ◽  
Timothy S. Fisher
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Volume Fraction ◽  
Incidence Angle ◽  
Radiative Properties ◽  
Tube Length ◽  
Nanotube Arrays ◽  
Carbon Nanotube Arrays ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Finite-difference time-domain method is used to investigate the optical properties of vertical arrays of multi-walled carbon nanotubes. Individual carbon nanotubes are treated as solid circular cylinders with an effective dielectric tensor. Our results confirm that carbon nanotube arrays have extremely low reflectivity as observed in experiments. Compared with the commonly used Maxwell-Garnett theory, our calculations generally give larger reflectance and absorptance and smaller transmittance, which are attributed to the diffraction and scattering within the cylinder array structure. The effects of volume fraction, tube length, and incidence angle on radiative properties are investigated respectively. Low volume fraction and long tubes are more favorable to achieve low reflectance and high absorptance. The angular dependence study shows that there exists an optimum incidence angle at which the reflectance can be minimized, indicating that a small misalignment in carbon nanotube arrays can slightly enhance the absorptance. Our results also indicate that an even darker material could be achieved by using carbon nanotubes with good alignment on the top surface.

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.

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