Handbook Of Advances In Carbon Nanotubes & Nanoparticles: Synthesis , Structure , Properties & Applications ( 3 Volumes Set )
Carbon nanotubes are the strongest and stiffest materials yet discovered in terms of tensile strength and elastic modulus respectively. This strength results from the covalent sp2 bonds formed between the individual carbon atoms. In 2000, a multi-walled carbon nanotube was tested to have a tensile strength of 63. Further studies, conducted in 2008, revealed that individual CNT shells have strengths of up to ~100 GPa, which is in good agreement with quantum/atomistic models. Since carbon nanotubes have a low density for a solid of 1.3 to 1.4 g/cm3, its specific strength of up to 48,000 kN·m·kg–1 is the best of known materials, compared to high-carbon steel’s 154 kN·m·kg–1. Under excessive tensile strain, the tubes will undergo plastic deformation, which means the deformation is permanent. This deformation begins at strains of approximately 5% and can increase the maximum strain the tubes undergo before fracture by releasing strain energy. Although the strength of individual CNT shells is extremely high, weak shear interactions between adjacent shells and tubes leads to significant reductions in the effective strength of multi-walled carbon nanotubes and carbon nanotube bundles down to only a few GPa’s. This limitation has been recently addressed by applying high-energy electron irradiation, which crosslinks inner shells and tubes, and effectively increases the strength of these materials to ~60 GPa for multi-walled carbon nanotubes and ~17 GPa for double-walled carbon nanotube bundles. In nanotechnology, a particle is defined as a small object that behaves as a whole unit in terms of its transport and properties. Particles are further classified according to size : in terms of diameter, coarse particles cover a range between 10,000 and 2,500 nanometers. Fine particles are sized between 2,500 and 100 nanometers. Ultrafine particles, or nanoparticles are sized between 100 and 1 nanometers. The reason for this double name of the same object is that, during the 1970-80’s, when the first thorough fundamental studies were running with “nanoparticles” in the USA and Japan, they were called “ultrafine particles” (UFP). However, during the 1990s before the National Nanotechnology Initiative was launched in the USA, the new name, “nanoparticle” had become fashionable (see, for example the same senior author’s paper 20 years later addressing the same issue, lognormal distribution of sizes. Nanoparticles may or may not exhibit size-related properties that differ significantly from those observed in fine particles or bulk materials. Although the size of most molecules would fit into the above outline, individual molecules are usually not referred to as nanoparticles. The encyclopaedia introduces the reader to novel, superfunctional and composite materials, metamaterials, electronics, electrets, carbon nanotubes, nanowires, molecular transistors, and graphene currently attracting research focus.
AUTOR: Davis, Mike
EDITORA: Auris Reference
DISPONIBILIDADE DO PRODUTO: Sob Encomenda - Até 40 dias ( Importação )