Carbon nanotubes elastic modulus

As carbon nanotubes present exceptional mechanical, superior thermal and electrical properties in general, by using them as reinforcing elements there are high expectations for improvement of quality of nano- and microcomposites [14-18]. As shown from earlier measurements, through carbon nanotube addition a 15-37% improvement of mechanical properties (elastic modulus and strength) can be achieved in comparison to other carbon-filled samples [19]. 

A significant observation in the present study is the marked increase in the E value, even with relatively small additions of the inorganic NWs. This is to be compared with the report of Zhang et al [12] who find that the elastic modulus of the PVA/PVP/SDS polymer increases from 2.5 to 4,0 GPa upon the addition of 5 wt% SWNTs. With the multi-walled carbon nanotubes (MWNTs), a linear increase in E with Vf of the MWNTs has been reported by Coleman et al [11]. With a 0.6 vol% addition of MWNTs, the PVA (nearly noncrystalline) modulus was reported to increase from 1.92 to... 

Globally, carbon nanotubes have a positive effect on the mechanical properties of all the composites with PVA matrices described in the previous sections. However, the enhancement of mechanical properties differs substantially from a material to another, depending on the type of nanotubes, or on the process used to manufacture the composite. The Young s modulus and the strength are deduced from usual tensile experiments. As depicted in Figure 11.4, PVA/nanotube composites generally follow the same tensile behavior, with a short elastic regime on the first percent strain, followed by a more or less extended plastic behavior. 

The modulus of elasticity has been determined for multiwalled carbon nanotubes as well. The results range about 1.0-1.3 TPa, which is even slightly above those for single-waUed tubes. This strength originates from the strongest SWNT within the respective MWNT and from a small additional contribution of the van der Waals interaction between the individual tubes. However, this is valid only for measurements on single MWNTs that are clamped on both ends. 

Why should we be interested in carbon nanotubes For one thing, there are not very many materials that have structural perfection at a molecular level as ideal as a single carbon nanotube. One can think about using their aspect ratio and small diameter for imaging applications. Also, they have very good mechanical properties and thermal properties. Theoretical calculations and measurements performed on individual carbon nanotubes have shown that their elastic modulus is as high as that of diamond, on the order of one terapascal. Indeed, if we could make a defect-free cable—one as long as we wanted—then a cable to connect the Earth and the moon would be within the realm of possibility. 

Nanotubes of carbon are made from graphene-like sheets roUed into a tube. Carbon nanotubes are considered to be the strongest and stifFest materials yet discovered in terms of tensile strength and elastic modulus, respectively. This strength results from the covalent sp bonds formed between the individual carbon atoms. 

Salvetat JP, Kulik AJ, Bonard JM, Briggs GAD, Stdckli T, M tenier K, et al. Elastic modulus of ordered and disordered multiwalled carbon nanotubes. Adv Mater 1999 11 161-5. 

The solvent resistance characteristics of non-crosslinked and crosslinked NR composites reinforced by multi-walled carbon nanotubes (MWCNTs). All the MWCNTs were individually dispersed within the rubber matrix where a three-dimensional cellulation structure was created when the added amount of MWCNTs exceeded 16 wt%. The non-crosslinked MWCNTs-filled rubber composite was not soluble, but swelled in toluene. They found that a continuous three-dimensional structure at the interface between the MWCNTs and the NR was extremely tough and thus contributed to the improvement in the elastic modulus and thermal stability of NR composites. 

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