The Influence of Carbon Nanotube Aspect Ratio on Thermal Conductivity Enhancement in Nanotube–Polymer Composites

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Rahul S. Kapadia ◽  
Brian M. Louie ◽  
Prabhakar R. Bandaru
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Aspect Ratio ◽  
Polymer Composites ◽  
Polymer Matrix ◽  
Linear Increase ◽  
Interfacial Resistance ◽  
Multiwalled Carbon ◽  
Conductivity Enhancement

We report and model a linear increase in the thermal conductivity (κ) of polymer composites incorporated with relatively low length/diameter aspect ratio multiwalled carbon nanotubes (CNTs). There was no evidence of percolation-like behavior in the κ, at/close to the theoretically predicted threshold, which was attributed due to the interfacial resistance between the CNT and the polymer matrix. Concomitantly, the widely postulated high thermal conductivity of CNTs does not contribute to the net thermal conductivity of the composites. Through estimating the interfacial resistance and the thermal conductivity of the constituent CNTs, we conclude that our experimental and modeling approaches can be used to study thermal transport behavior in nanotube–polymer composites.

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

Crystals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 398 ◽  
Author(s):  
Yongcun Zhou ◽  
Xiao Zhuang ◽  
Feixiang Wu ◽  
Feng Liu
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Polymer Composites ◽  
Thermal Management ◽  
High Performance ◽  
Graphene Nanosheets ◽  
Multiwalled Carbon Nanotube ◽  
Processing Unit ◽  
Functionalized Graphene ◽  
Multiwalled Carbon

Polymer composites with high thermal conductivity have a great potential for applications in modern electronics due to their low cost, easy process, and stable physical and chemical properties. Nevertheless, most polymer composites commonly possess unsatisfactory thermal conductivity, primarily because of the high interfacial thermal resistance between inorganic fillers. Herein, we developed a novel method through silver functionalized graphene nanosheets (GNS) and multiwalled carbon nanotube (MWCNT) composites with excellent thermal properties 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 of 69.1 times compared to the polyvinyl alcohol (PVA) matrix. Moreover, these composites showed more competitive thermal conductivities compared to untreated fillers/PVA composites applied to the desktop central processing unit, making these composites a high-performance alternative to be used for thermal management.

Thermal Transport Properties of Nanofluids Containing Carbon Nanotubes

2008 ◽  
Author(s):  
Huaqing Xie ◽  
Lifei Chen ◽  
Yang Li ◽  
Wei Yu
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Base Fluid ◽  
Volume Fraction ◽  
Thermal Conductivity Enhancement ◽  
Mechanochemical Reaction ◽  
Multiwalled Carbon ◽  
Conductivity Enhancement ◽  
Lower Viscosity ◽  
Potential Applications

Multiwalled carbon nanotubes (CNTs) have been treated by using a mechanochemical reaction method to enhance their dispersibility for producing CNT nanofluids. The thermal conductivity was measured by a short hot wire technique and the viscosity was measured by a rotary viscometer. The thermal conductivity enhancement reaches up to 17.5% at a volume fraction of 0.01 for an ethylene glycol based nanofluid. Temperature variation was shown to have no obvious effects on the thermal conductivity enhancement for the as prepared nanofluids. With an increase in the thermal conductivity of the base fluid, the thermal conductivity enhancement of a nanofluid decreases. At low volume fractions (<0.4 Vol%), nanofluids have lower viscosity than the corresponding base fluid due to lubricative effect of nanoparticles. When the volume fraction is higher than 0.4 Vol%, the viscosity increases with nanoparticle loadings. The prepared nanofluids, with no contamination to medium, good fluidity, stability, and high thermal conductivity, would have potential applications as coolants in advanced thermal systems.

Evaluation of mechanical and dynamic mechanical properties of multiwalled carbon nanotube-based ethylene–propylene copolymer composites mixed by masterbatch dilution

2016 ◽  
Vol 50 (29) ◽  
pp. 4093-4101 ◽  
Author(s):  
Maija Hoikkanen ◽  
Minna Poikelispää ◽  
Amit Das ◽  
Uta Reuter ◽  
Wilma Dierkes ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Aspect Ratio ◽  
Melt Mixing ◽  
Multiwalled Carbon ◽  
Mixing Processes ◽  
Ethylene Propylene ◽  
Dynamic Mechanical ◽  
Mixing Method

A two-step masterbatch mixing technique was studied for preparation of carbon nanotube-filled ethylene–propylene diene elastomer compounds, and compared to conventional one-step mixing process. In the two-step process, a masterbatch compound with carbon nanotube content of 50 parts per hundred was prepared by melt-mixing ethylene–propylene diene elastomer. This material was then compounded with pristine ethylene–propylene diene elastomer and composites with different carbon nanotube concentrations were compared. The aim of this study is to compare the efficiency of two different mixing processes on the dispersion of carbon nanotubes and to facilitate the handling of carbon nanotubes, as the masterbatch can be prepared in a controlled way and used for further dilution without the problems related to carbon nanotube processing. The compound properties were studied with emphasis on mechanical characterization and dynamic mechanical thermal analysis. Masterbatch mixing resulted in the similar mechanical properties of the composites compared to the direct mixing method. At the relatively low loadings of carbon nanotubes, the considerable improvements of the mechanical properties were observed. The aspect ratio of the carbon nanotubes determined by transmission electron microscope was found to be similar to the one calculated from the Guth equation. It showed a considerable reduction in aspect ratio independent of the used mixing method.

Impact of Altering Aspect Ratio of the Loading Particles on a Suspension’s Thermal Conductivity

2008 ◽  
Author(s):  
A. S. Cherkasova ◽  
J. W. Shan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Silicon Carbide ◽  
Aspect Ratio ◽  
Effective Medium Theory ◽  
Detailed Comparison ◽  
Interfacial Resistance ◽  
Micro Particles ◽  
Particle Aspect Ratio

It has been recognized that heat-transfer fluids used to convey thermal energy produced by one device to another can exhibit significant increases in thermal conductivity with the addition of highly conductive particles. Suspensions of nano- and micro-particles have attracted the most recent interest because of their enhanced stability against sedimentation, reduction in potential for clogging a flow system, as well as the tantalizing possibility of unexpected enhancements in thermal conductivity that have been reported in some experiments. Among various suspensions, considerable attention has focused on those containing large-aspect-ratio particles, such as carbon nanotubes. Although recent experiments have demonstrated enormous heat-transfer enhancements in these fluids, such increases were reportedly not in agreement with existing macroscale theories [1–3]. In this research we report on an experimental study of the effects of particle aspect ratio on the effective thermal conductivity of micro- and nano-particle suspensions. The influence of particle aspect ratio on the thermal properties of suspensions was first studied in dispersions of micron-sized, silicon-carbide particles with varying aspect ratio. To carry out a detailed comparison with theoretical predictions, particle aspect ratio and size distributions were measured. It is shown that the conductivity of the silicon-carbide suspensions can be quantitatively predicted by an effective-medium theory (EMT), provided the volume-weighted aspect ratio of the particles is used. The particle-aspect-ratio effect was further studied in the suspensions of multi-walled carbon nanotubes. Experimental data on the thermal conductivity of nanotube suspensions could also be interpreted in terms of the aspect-ratio dependence predicted by EMT if the additional nanoscale effect of interfacial resistance was considered.

scholarly journals Thermal Conductivity Enhancement Derived from Poly(Methyl Methacrylate)-Grafted Carbon Nanotubes in Poly(Methyl Methacrylate)/Polystyrene Blends

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1347 ◽  
Author(s):  
Jaehyun Wie ◽  
Jooheon Kim
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Methyl Methacrylate ◽  
Multiwalled Carbon Nanotubes ◽  
Thermal Conductivity Enhancement ◽  
Multiwalled Carbon ◽  
Poly Methyl Methacrylate ◽  
Conductivity Enhancement ◽  
Conductive Properties ◽  
Enhanced Thermal Conductivity

This paper presents a method to enhance thermal conductivity using poly(methyl methacrylate)(PMMA), polystyrene(PS) blends, and incorporation of multiwalled carbon nanotubes (MWCNTs). MWCNTs are selectively localized in PMMA phase to improve conductive properties. In addition, Surface of MWCNTs was treated with PMMA to enhance affinity between matrix and filler. PMMA grafting helps filler localization on matrix phase. Composites using two polymers enhanced thermal conductivity by ~11% compared with composites using only PS or PMMA. Also, PMMA grafting on the surface of MWCNTs enhanced thermal conductivity by ~13% compared with samples without PMMA grafting.

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