1985 British scientist spectrum professor at the University of Sussex American Kroto and Smalley and Curl at Rice University professor in two collaborative research, we found a high degree of symmetry of the carbon element may be formed by a cage-like 60 or 70 carbon atoms in the C60 and C70 molecular structure, known as buckyballs (Buckyballs).
In 1991, Japanese scientists Iijima at NEC preparing cathode scarring C60 for the first time by high resolution tunneling electron microscopy revealed an outer diameter of 515nm, an inner diameter of 213nm, stacked by only two coaxial cylindrical surface made of graphite-like carbon nanotubes. Then in 1993, Iijima and Bethune research group also reported the structure is very simple synthesis of single-walled carbon nanotubes, which is theoretically predicted properties of carbon nanotubes offer the possibility of experiments on carbon clusters to further broaden the scope of the material, also greatly contributed to the theoretical and experimental study of carbon nanotubes so that the field is now becoming a hot global research. Carbon nanotubes are following the discovery of C60 carbon allotropes with another, smaller radial dimension, the tube diameter is generally a few nanometers to several tens of nanometers, smaller diameter of the tube, some only about 1nm; and Its length is generally in the micron level, length and diameter ratio is very large, up to 103 to 106. Thus, carbon nanotubes are considered to be a typical one-dimensional nanomaterials. Since carbon nanotubes were found to mankind, has been hailed as the future of the material, it is one of the frontiers of international science in recent years. Professor Alex Zettl Berkeley University of California think, on prospects for C60 and carbon nanotubes to conduct a comprehensive comparison, C60 can be summarized with a sheet of paper, and carbon nanotubes need to complete a book.
The unique structure of multi walled carbon nanotubes determines that it has many special physical and chemical properties. Composed of carbon nanotubes C = C covalent bond is nature’s most stable chemical bond, it makes the carbon nanotube has a very excellent mechanical properties. Theoretical calculations show that carbon nanotubes have high strength and great toughness. Its theoretical value estimate Young’s modulus up 5TPa, strength is about 100 times stronger than steel, but weight density is only 1/6 of steel. Treacy and so for the first time use of the TEM measurements of the temperature within the range from room temperature to 800 degrees change MWCNTs mean square amplitude, to derive the average Young’s modulus is about multi-walled carbon nanotubes 1.8Tpa. The Salvetat and other measurements of Young’s modulus of single-walled small-diameter carbon nanotubes, and export its shear modulus 1Tpa. Wong et AFM measured bending strength multi-walled carbon nanotubes with an average of 14.2 ± 10.8GPa, and bending strength of the carbon fibers but only 1GPa. Whether it is the strength or toughness of carbon nanotubes, they are far superior to any fiber, is considered the future of the “super fiber.” It predicted that carbon nanotubes could become a new kind of high-strength carbon fiber material, both inherent nature of the carbon material, and a conductive metallic material and thermal conductivity, heat and corrosion resistance of ceramic materials, textile fibers can be woven , as well as lightweight polymer materials, ease of processing. The carbon nanotubes as composite reinforcement, is expected to show good strength, elasticity, fatigue resistance and isotropic carbon nanotube-reinforced composites can be expected to bring composites may leap. Research produced by nanotube composite material is first carried out on a metal base, such as: Fe / carbon nanotube, Al / carbon nanotube, Ni / carbon nanotube, Cu / carbon nanotube. In recent years, the focus has shifted to the carbon nanotube polymer composites / carbon nanotube composite material aspects, such as high-strength lightweight materials, the use of carbon fiber as a reinforcing material, the mechanical properties of carbon nanotubes and small diameter and a large aspect ratio will bring better enhancement.
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