scholarly journals Stabilizing effect of methylcellulose on the dispersion of multi-walled carbon nanotubes in cementitious composites

2020 ◽  
Vol 9 (1) ◽  
pp. 93-104
Author(s):  
Mingrui Du ◽  
Yuan Gao ◽  
Guansheng Han ◽  
Luan Li ◽  
Hongwen Jing
Keyword(s):  
Carbon Nanotubes ◽  
Pore Solution ◽  
Cementitious Materials ◽  
High Ionic Strength ◽  
Cementitious Composites ◽  
Uniform Distributions ◽  
Stabilizing Effect ◽  
Multi Walled Carbon Nanotubes ◽  
The Stability ◽  
Walled Carbon Nanotubes

AbstractMulti-walled carbon nanotubes (MWCNTs) have been added in the plain cementitious materials to manufacture composites with the higher mechanical properties and smart behavior. The uniform distributions of MWCNTs is critical to obtain the desired enhancing effect, which, however, is challenged by the high ionic strength of the cement pore solution. Here, the effects of methylcellulose (MC) on stabilizing the dispersion of MWCNTs in the simulated cement pore solution and the viscosity of MWCNT suspensions werestudied. Further observations on the distributions of MWCNTs in the ternary cementitious composites were conducted. The results showed that MC forms a membranous envelope surrounding MWCNTs, which inhibits the adsorption of cations and maintains the steric repulsion between MWCNTs; thus, the stability of MWCNT dispersion in cement-based composites is improved. MC can also work as a viscosity adjuster that retards the Brownian mobility of MWCNTs, reducing their re-agglomerate within a period. MC with an addition ratio of 0.018 wt.% is suggested to achieve the optimum dispersion stabilizing effect. The findings here provide a way for stabilizing the other dispersed nano-additives in the cementitious composites.

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.

Noncovalent functionalization of hole-transport materials with multi-walled carbon nanotubes for stable inverted perovskite solar cells

2019 ◽  
Vol 7 (45) ◽  
pp. 14306-14313 ◽  
Author(s):  
Yu Lu ◽  
Xueping Zong ◽  
Yilei Wang ◽  
Wenhua Zhang ◽  
Quanping Wu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Solar Cells ◽  
Perovskite Solar Cells ◽  
Hole Transport ◽  
Promising Strategy ◽  
Noncovalent Functionalization ◽  
Multi Walled Carbon Nanotubes ◽  
The Stability ◽  
Walled Carbon Nanotubes

A new promising strategy to improve the stability of inverted perovskite solar cells is reported.

Variational Principles for the Stability Analysis of Multi-Walled Carbon Nanotubes Based on a Nonlocal Elastic Shell Model

2010 ◽  
Author(s):  
Mohsen Asghari ◽  
Jacob Rafati
Keyword(s):  
Carbon Nanotubes ◽  
Stability Analysis ◽  
Inverse Method ◽  
Variational Principles ◽  
Elastic Shell ◽  
Multi Walled Carbon Nanotubes ◽  
Natural Boundary Conditions ◽  
The Stability ◽  
Walled Carbon Nanotubes ◽  
Continuum Theories

The nonlocal continuum theories are capable to reflect the small length characteristic of nanostructures. In this work, variational principles are presented for the stability analysis of multi-walled carbon nanotubes under various mechanical loadings based on the nonlocal elastic Donnell’s shell by the semi-inverse method. In this manner, a set of proper essential and natural boundary conditions for each layer of the multi-walled nanotube is derived.

scholarly journals Unsteady Nano-Liquid Spray with Thermal Radiation Comprising CNTs

Processes ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 181 ◽  
Author(s):  
Taza Gul ◽  
Waqar Khan ◽  
Mehwish Tahir ◽  
Rubi Bilal ◽  
Ilyas Khan ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Nonlinear Differential Equations ◽  
Vertical Tube ◽  
Enhancement Of Heat Transfer ◽  
Spray Pattern ◽  
Similarity Transformations ◽  
Multi Walled Carbon Nanotubes ◽  
The Stability ◽  
Walled Carbon Nanotubes ◽  
Physical Quantities

Carbon nanotubes play a significant role in improving the thermal efficiency of common liquids. The objective of this research is to examine the thin film spray over the surface of a vertical tube through carbon nanotubes (CNTs) nanofluids. Processes for the preparation of the nanofluid and the stable dispersion of the CNTs in water were followed from the available experimental literature. The thickness of the spray pattern was kept variable to control the stability of the spray pattern and to accomplish the suitable heat transmission under the effects of a magnetic field. The pressure supply and rate of the spray were also calculated as a function of the liquid film thickness. The basic governing equations were transformed into nonlinear differential equations by using suitable similarity transformations. The numerical outcomes were obtained by means of the BVPh 2.0 package of the optimal scheme. The influences of the physical quantities like spray rate and variable thickness on the dimensionless velocity, temperature, pressure distribution, Nusselt number were investigated and the results are compared with the existing literature. The comparison was found to be in good agreement. The present results showed that the single-walled carbon nanotubes are more efficient in the enhancement of heat transfer rate compared to the 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.

scholarly journals Fabrication of β-cyclodextrin modified mesostructured silica coated multi-walled carbon nanotubes composites and application for paraben removal

2018 ◽  
Vol 78 (5) ◽  
pp. 1001-1009 ◽  
Author(s):  
Chuyuan Ding ◽  
Jun He ◽  
Mengxia Xu ◽  
Chengjun Wang
Keyword(s):  
Carbon Nanotubes ◽  
Removal Efficiency ◽  
Cost Effective ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
Mesostructured Silica ◽  
Multi Walled Carbon Nanotubes ◽  
High Regeneration ◽  
The Stability ◽  
Walled Carbon Nanotubes

Abstract In this work, the novel β-cyclodextrin modified mesostructured silica coated multi-walled carbon nanotubes (MWCNTs) composites were synthesized and applied for the removal of parabens in aqueous solution. The prepared MWCNTs/SiO2/β-CD composites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. The effects of the amount of adsorbent, pH and elution solvents on the removal efficiency of parabens from water solutions were investigated. Under the optimized conditions, over 95% removal efficiency was achieved by using 40 mg of MWCNTs/SiO2/β-CD adsorbents to absorb the parabens from 60 mL of 0.5 μg/mL parabens solutions. The solution pH in the range from 5 to 9 has no influence on the removal efficiency and the parabens sorption capacity of the prepared adsorbents were around 0.75 μg/mg. Furthermore, the stability and reusability studies demonstrated that the prepared MWCNTs/SiO2/β-CD composites are cost-effective adsorbents for the removal of parabens from water with high regeneration efficiency. The composites fabricated in this study could become an attractive candidate for water purification.

BUCKLING AND POSTBUCKLING ANALYSIS OF MULTI-WALLED CARBON NANOTUBES BASED ON THE CONTINUUM SHELL MODEL

2007 ◽  
Vol 07 (04) ◽  
pp. 629-645 ◽  
Author(s):  
X. Q. HE ◽  
C. QU ◽  
Q. H. QIN ◽  
C. M. WANG
Keyword(s):  
Carbon Nanotubes ◽  
Shallow Shell ◽  
Compressive Force ◽  
Postbuckling Behavior ◽  
Steep Gradient ◽  
Multi Walled Carbon Nanotubes ◽  
The Stability ◽  
Walled Carbon Nanotubes ◽  
The Continuum ◽  
Vdw Interaction

Buckling and postbuckling behaviors of multi-walled carbon nanotubes (MWCNTs) under a compressive force are studied. MWCNTs are modeled by Donnell's shallow shell nonlinear theory with the allowance of van der Waals (vdW) interaction between the walls. It is shown herein that the buckling load decreases while the buckling strain increases as the innermost radius of MWCNT increases. For the postbuckling behavior, the shortening-load curves show an initial steep gradient that gradually level up when the radius of the innermost tube changes from a small value to a large value. However, the deflection-load curves are almost level for various radii of MWCNTs. In addition, the analytical results showed that the shortening-load curves are almost linear but the deflection-load curves are nonlinear and the stability of MWCNTs can be enhanced by adding tubes.

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