Modulus carbon nanotubes

Many research opportunities exist for the controlled manipulation of structures of nm dimensions. Advances made in the characterization and manipulation of carbon nanotubes should therefore have a substantial general impact on the science and technology of nanostructures. The exceptionally high modulus and strength of thin multi-wall carbon nanotubes can be used in the manipulation of carbon nanotubes and other nanostructures [212, 213]. 

FIGURE 4.6 Variation of storage modulus against temperature for ethylene-vinyl acetate (EVA) nanocomposites having different loadings of carbon nanotube (CNT) and ANT. (From George, J.J., Sengupta, R., and Bhowmick, A.K., J. Nanosci. Nanotechnol., 8, 1, 2007. Courtesy of American Scientific Publishers.)... 

FIGURE 28.22 Storage modulus G vs temperature of carbon nanotube (CNT)/mbber composite. (From Lopez-Manchado, M.A. et al., J. Appl. Polym. Sci., 92, 3394, 2004.)... 

M.M.J. Treacy, T.W. Ebbesen, and J.M. Gibson, Exceptionally high Young s modulus observed for individual carbon nanotubes. Nature 381, 678-680 (1996). 

The mechanical properties of the inorganic nanotubes have only been investigated to a relatively small extent. The Young s modulus of multiwall BN nanotubes was measured using the vibrational method within a TEM (17) and was found to be 1.2 TPa, which is comparable to the values measured for carbon nanotubes. The Young s modulus of the b-P nanotubes was calculated (88a). The observed value, 300 GPa, is some 25% of the Young s modulus of carbon nanotubes. The Poisson ratio of b-P nanotubes was calculated to be 0.25 in this work. 

CNTs can enhance the thermal properties of CNT-polymer nanocomposites. The reinforcing function is closely associated with the amount and alignment of CNTs in the composites. Well-dispersed and long-term stable carbon nanotubes/ polymer composites own higher modulus and better thermal property as well as better electronic conductivity (Valter et al., 2002 Biercuk et al., 2002). Both SWNT and MWNT can improve the thermal stability and thermal conductivity of polymer, the polymer-CNT composites can be used for fabricating resistant-heat materials. 

After Iijima pointed out the extraordinary strength of carbon nanotubes [204], and after their Young s modulus were measured [205], scientists and engineers have been interested in the mechanical properties of CNTs and other carbon nanomaterials. In this section, we will review the effect of defects and doping on the mechanical properties of carbon nanomaterials. 

The incorporation of carbon nanotubes (CNT)s into polymer matrices has resulted in composites that exhibit increased thermal stability, modulus, strength, electrical and optical properties (33-35). Several investigations have concluded that carbon nanotubes can also act as a nucleating agents for polymer crystallization (36,37). 

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]. 

With the advent of nanomaterials, different types of polymer-based composites developed as multiple scale analysis down to the nanoscale became a trend for development of new materials with new properties. Multiscale materials modeling continue to play a role in these endeavors as well. For example, Qian et al. [257] developed multiscale, multiphysics numerical tools to address simulations of carbon nanotubes and their associated effects in composites, including the mechanical properties of Young s modulus, bending stiffness, buckling, and strength. Maiti [258] also used multiscale modeling of carbon nanotubes for microelectronics applications. Friesecke and James [259] developed a concurrent numerical scheme to evaluate nanotubes and nanorods in a continuum. 

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... 

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