Thermal Transport in MWNT Sheet: Extremely High Radiation From The Carbon Nanotube Surface

ABSTRACTLaser flash and self-heating 3ω techniques were employed to determine the anisotropic thermal conductivity and thermal diffusivity of highly oriented free standing multiwalled carbon nanotube (MWNT) sheet drawn from a sidewall of a MWNT forest that was grown by chemical-vapor deposition. The thermal conductivity and the thermal diffusivity along the alignment are 50±5 W/m·K and 45±5 mm2/s, respectively, and are mostly limited by intrinsic defects of individual nanotubes and phonon-phonon interaction within bundles which form the supporting matrix of the MWNT sheet. The long tube-tube overlapping substantially decreases the electrical and thermal interconnection resistances which are usually dominate in randomly deposited mat-like nanotube assemblies. The extremely large surface area of the MWNT sheet leads to excessive heat radiation that dose not allow to transfer the heat energy by means of phonons to distances > 2 mm.

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Thermal Transport Properties of Multi-Walled Carbon Nanotube Arrays

First International Conference on Integration and Commercialization of Micro and Nanosystems, Parts A and B ◽

10.1115/mnc2007-21033 ◽

2007 ◽

Author(s):

Huaqing Xie ◽

An Cai ◽

Xinwei Wang

Keyword(s):

Thermal Conductivity ◽

Carbon Nanotube ◽

Thermal Diffusivity ◽

Room Temperature ◽

Infrared Detector ◽

Laser Flash ◽

Temperature Range ◽

Nanosecond Pulsed Laser ◽

Multi Walled Carbon Nanotube ◽

Individual Cnts

A laser flash technique was applied to measure the thermal diffusivity along a multi-walled carbon nanotube (CNT) array in temperature range of −55∼200 °C. In the measurements, a nanosecond pulsed laser was used to realize noncontact heating and the temperature variations were recorded by an infrared detector. The experimental results show that the thermal diffusivity of the CNT array increases slightly with temperature in the −55∼70 °C temperature range and exhibits no obvious change in the −75∼200 °C temperature range. The CNT array has much larger thermal diffusivity than several known excellent thermal conductors, reaching about 4.6 cm2s−1 at room temperature. The mean thermal conductivity (λ) of individual CNTs was further estimated from the thermal diffusivity, specific heat (Cp), and density (ρ) by using the correlation of λ = αρCp. The thermal conductivity of individual CNTs increases smoothly with the temperature increase, reaching about 750 Wm−1K−1 at room temperature.

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Role of rheology in tunning thermal conductivity of polyamide 12/polyamide 6 composites with a segregated multiwalled carbon nanotube network

Journal of Composite Materials ◽

10.1177/0021998317749715 ◽

2017 ◽

Vol 52 (18) ◽

pp. 2549-2557 ◽

Cited By ~ 2

Author(s):

Laura Arboleda-Clemente ◽

Xoán García-Fonte ◽

María-José Abad ◽

Ana Ares-Pernas

Keyword(s):

Thermal Conductivity ◽

Carbon Nanotubes ◽

Carbon Nanotube ◽

Thermal Diffusivity ◽

Multiwalled Carbon Nanotubes ◽

Polyamide 6 ◽

Multiwalled Carbon ◽

Polyamide 12 ◽

Nanotube Composites ◽

Carbon Nanotube Network

Effect of multiwalled carbon nanotubes in thermal conductivity of an immiscible blend of polyamides, 50/50 (wt%/wt%) polyamide 12/polyamide 6, was analyzed as function of nanofiller amount and temperature. Effect of the molding temperature in the structure of conductive network was investigated by rheology. Data show that 5 vol% multiwalled carbon nanotubes caused an increase of 41% in thermal diffusivity and 78% in thermal conductivity respect to polyamide blend values. Thermal conductivity improvement could be described by percolation theory, with a low threshold composition (φc = 0.09 vol% carbon nanotube). Fitting parameters obtained from Agari’s adjustment model show that polyamides structure is not affected by carbon nanotubes and the nanofillers can easily form conductive paths in the polyamide 12/polyamide 6 matrix. The temperature increase facilitates nanofiller dispersion causing the formation of a denser carbon nanotube network and rising the thermal diffusivity of carbon nanotube composites with low percolation level, as was proved on annealed samples at 255℃.

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Experimental Study of VACNT Arrays as Thermal Interface Material

ASME 2013 4th International Conference on Micro/Nanoscale Heat and Mass Transfer ◽

10.1115/mnhmt2013-22016 ◽

2013 ◽

Author(s):

Yulong Ji ◽

Gen Li ◽

Hongbin Ma ◽

Yuqing Sun

Keyword(s):

Thermal Conductivity ◽

Chemical Vapor ◽

Laser Flash ◽

Thermal Interface Material ◽

Chemical Vapor Deposition Method ◽

Free Standing ◽

Thermal Interface ◽

Thermal Paste ◽

Laser Flash Analysis ◽

Contact Thermal Conductivity

In order to improve thermal interface material (TIM), vertically aligned carbon nanotube (VACNT) arrays were synthesized by the chemical vapor deposition method, and then transferred by dipping in hydrofluoric acid (HF acid) solution to get a free standing VACNT array. Different TIM samples with sandwiched structures were fabricated by inserting the free standing VACNT arrays between two copper plates with and without bonding materials. The laser flash analysis method was applied to measure the overall thermal conductivity of these samples. Results show that: compared with two copper plates in direct contact, thermal conductivity of samples only with VACNT arrays as TIM can be enhanced about 142%–460% depending on the thickness of VACNT arrays. Conventional TIM made up of thermal paste (TG-550 with thermal conductivity of 5 W/mK) and a thermal pad (TP-260 US with thermal conductivity of 6 W/mK) was used as a bonding material between copper plates and VACNT arrays, thermal conductivity has been shown to further improve with the highest values at 8.904 W/mK and 10.17 W/mK corresponding to the different bonding materials and different thicknesses of VACNT arrays used. Results also show that the thicker the VACNT array is when used as a TIM, the lower the overall thermal conductivity of the corresponding samples. This lower thermal conductivity caused by more defects in amorphous carbon of thicker VACNT arrays and lower density of the corresponding sandwiched samples.

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

Crystals ◽

10.3390/cryst8110398 ◽

2018 ◽

Vol 8 (11) ◽

pp. 398 ◽

Cited By ~ 4

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.

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A study on the thermal conductivity of multiwalled carbon nanotube/polypropylene composite

Acta Physica Sinica ◽

10.7498/aps.58.4536 ◽

2009 ◽

Vol 58 (7) ◽

pp. 4536

Author(s):

Wang Jian-Li ◽

Xiong Guo-Ping ◽

Gu Ming ◽

Zhang Xing ◽

Liang Ji

Keyword(s):

Thermal Conductivity ◽

Carbon Nanotube ◽

Multiwalled Carbon Nanotube ◽

Polypropylene Composite ◽

Multiwalled Carbon

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Structural and mechanical properties of free-standing multiwalled carbon nanotube paper prepared by an aqueous mediated process

Journal of Materials Science ◽

10.1007/s10853-017-0983-z ◽

2017 ◽

Vol 52 (12) ◽

pp. 7503-7515 ◽

Cited By ~ 6

Author(s):

Sushant Sharma ◽

Bhanu Pratap Singh ◽

Arun Singh Babal ◽

Satish Teotia ◽

Jeevan Jyoti ◽

...

Keyword(s):

Mechanical Properties ◽

Carbon Nanotube ◽

Multiwalled Carbon Nanotube ◽

Free Standing ◽

Multiwalled Carbon

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Anisotropic Thermal Diffusivity of Aligned Multiwalled Carbon Nanotube Arrays

Heat Transfer, Volume 5 ◽

10.1115/imece2002-39576 ◽

2002 ◽

Cited By ~ 3

Author(s):

Theodorian Borca-Tasciuc ◽

Claudiu L. Hapenciuc ◽

Bingqing Wei ◽

Robert Vajtai ◽

Pulickel M. Ajayan

Keyword(s):

Carbon Nanotube ◽

Thermal Diffusivity ◽

Front Surface ◽

Multiwalled Carbon Nanotube ◽

Back Surface ◽

Multiwalled Carbon ◽

Conduction Model ◽

Beam Incident ◽

Order Of Magnitude ◽

Photothermoelectric Technique

This work employs a photothermoelectric technique to measure the anisotropic thermal diffusivity of an aligned multiwalled carbon nanotube array. A modulated laser beam incident to the front surface of the sample creates a thermal wave which is detected by a fast responding thermocouple formed between the back surface of the sample and the tip of a sharp metallic probe. The anisotropic thermal diffusivity values are obtained by fitting the radial and frequency dependent thermal signals with an anisotropic heat conduction model. The room temperature thermal diffusivity measured perpendicular to the alignment direction is 0.246×10−5m2/s, an order of magnitude smaller than thermal diffusivity along the CNTs alignment direction 4.4×10−5m2/s. However, the thermal diffusivity of the aligned multiwalled CNT is two orders of magnitude smaller than expected for an individual multiwalled CNT.

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Highly Organized Carbon Nanotube-PDMS Hybrid System for Multifunctional Flexible Devices

Volume 3: 19th International Conference on Design Theory and Methodology; 1st International Conference on Micro- and Nanosystems; and 9th International Conference on Advanced Vehicle Tire Technologies, Parts A and B ◽

10.1115/detc2007-35442 ◽

2007 ◽

Author(s):

Yung J. Jung ◽

Laila Jaber-Ansari ◽

Xugang Xiong ◽

Sinan Mu¨ftu¨ ◽

Ahmed Busnaina ◽

...

Keyword(s):

Carbon Nanotubes ◽

Carbon Nanotube ◽

Electric Fields ◽

Composite Structures ◽

Field Enhancement ◽

Chemical Vapor ◽

Casting Process ◽

Dip Coating ◽

Network Architectures ◽

Multiwalled Carbon

We will present a method to fabricate a new class of hybrid composite structures based on highly organized multiwalled carbon nanotube (MWNT) and singlewalled carbon nanotube (SWNT) network architectures and a polydimethylsiloxane (PDMS) matrix for the prototype high performance flexible systems which could be used for many daily-use applications. To build 1–3 dimensional highly organized network architectures with carbon nanotubes (both MWNT and SWNT) in macro/micro/nanoscale we used various nanotube assembly processes such as selective growth of carbon nanotubes using chemical vapor deposition (CVD) and self-assembly of nanotubes on the patterned trenches through solution evaporation with dip coating. Then these vertically or horizontally aligned and assembled nanotube architectures and networks are transferred in PDMS matrix using casting process thereby creating highly organized carbon nanotube based flexible composite structures. The PDMS matrix undergoes excellent conformal filling within the dense nanotube network, giving rise to extremely flexible conducting structures with unique electromechanical properties. We will demonstrate its robustness under large stress conditions, under which the composite is found to retain its conducting nature. We will also demonstrate that these structures can be directly utilized as flexible field-emission devices. Our devices show some of the best field enhancement factors and turn-on electric fields reported so far.

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