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| Carbon nanotube |
Over the last few years carbon nanotubes (CNT) have attracted significant research interest because of its small dimensions, high surface area, high mechanical strength, thermal and electrical conductivity, and several other improved physico-chemical properties. In general, the carbon-based (graphite and diamond) nanomaterials show the highest thermal conductivity than that of any other conducting materials. It has been observed that the carbon nanotubes possess more conductivity than graphite and diamond.
Specifically, monodisperse single-walled carbon nanotubes(SWNTs) have an exceptionally high electrical and thermal conductivity, Nanotubes with varying geometries show identical temperature dependent thermal conductivity. Multi walled carbon nanotubes (MWNTs) with their cylindrical structure of seamless graphite are equally valuable like SWNTs. SWNT’s and MWNT’s are the single and multi-layered cylindrical graphene sheet.
Graphene can be conveniently used as the filler material for thermoplastic and thermosetting polymer which has unique thermal properties. There are many nanotube based composite material whose thermal conductivity is extremely high. The structural complexity and variety of MWNT’s are more than SWNT’s. MWMT’s shows advantages over SWMT’s such as low production cost and enhanced thermal and chemical stability. The thermal properties of SWNT’s can change due to their structural defects of C=C bonds. Double walled carbon nanotubes (DWNTs) are the synthetic blend of both SWNTs and MWNTs and showing properties intermediate of these two. Both the walls of DWNTs are semiconducting.
To improve the thermal conductivity of the polymer systems, such as epoxy, poly vinyl alcohol (PVA) and styrene butadiene rubber, high orientation of reduced Graphene oxide (rGO) can be used. Graphene oxide can be also used as a filler to improve the flame retardant properties of various polymer nanocomposite. It is also useful to provide high thermal insulation properties in home insulation and in flame retardants. Nanocomposite foam containing cellulose nanofibres (CNF), GO shows high power retardancy. Apart from thermal application carbon nanotubes have wide range of applications in the other fields of science and technology.
References:
1. Ruoff, R. S.; Lorents, D. C. Mechanical and Thermal Properties of CarbonNanotube. Carbon, 1995, 33: 925-930.
2.Berver, S.; Kwon, Y-K.; Tomanik, D. Unusually High Thermal Conductivity of Carbon Nanotube. Phys. Rev. Lett., 2000, 83: 4613-4616.
3. Hone, J.; Whitney, M.; Piskoti, C.; Zettyl, A. Thermal conductivity of single-walled carbon nanotubes. Physical Rev. B. 1999, 59: 2514-16.
4 Che, J.; Cagin, T.; Goddard, W. A. Thermal Conductivity of Carbon Nanotube. Nanotechnology, 2000, 11: 65-69.
5 Guan, L. Z.;Zhao, L.; Wan, Y. J.; Tang, L. C. Three-dimensional graphene-based polymer nanocomposites: preparation, properties and applications. Nanoscale, 2018, 10: 14788-14811.
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