Carbon nanotubes macroscopic composites

Numerous micromechanical models have been successfully used to predict the macroscopic behavior of fiber-reinforced composites. However, the direct use of these models for nanotube-reinforced composites is doubtfiil due to the significant scale difference between nanotube and typical carbon fiber. Recently, two methods have been proposed for modeling the mechanical behavior of single-walled carbon nanotube (SWCN) composites ... 

Carbon nanotubes comprise a very promising material for various applications and especially as an active component in composites and hybrids as will be documented in the other chapters of this book. Harnessing these nanoscopic assets in a macroscopic material would maximize CNTs potential and applicability. The choice of synthesis technique and purification method, which define size, type, properties, quality and purity of CNTs as well as their processability, is crucial for their implementation into composites and hybrids. 

Nevertheless, laminate macroscopic morphology is essentially fixed, and formation of stable laminates is better treated as an adhesion problem. Similarly, composite compositions which may comprise a blend of one or more functionalized polymers with a second, less tractable component such as starch, lignin, clay, silica, POSS, carbon nanotubes, etc. are outside the scope of this chapter. 

The main objective for using carbon nanotubes in polymer composites is the exploitation of their extraordinary properties on macroscopic scales. Thereby, one key to success lies in the control of morphology along the whole processing chain. Depending on the targeted field of application, different morphologies are favorable for the final components or semifinished parts. 

Breuer O, Uttandaraman S (2004) Big returns from small fibers a review of polymer/carbon nanotube composites. Polym Compos 25(6) 630-645 Brigitte V, Alain P, Claude C, Cedric S, Rene P, Catherine J, Patrick B, Philippe P (20(X)) Macroscopic fibers and ribbons of oriented carbon nanoUibes. Science 290(5495) 1331-1334 Cadambi RM, Ghassemieh E (2012) Optimized process for the inclusion of carbon nanotubes in elastomers with improved thermal and mechanical properties. J Appl Polym Sci 124(6) 4993-5001... 

In order to proper, characterize the macroscopic properties of the fibrous structure the effective properties of the nanofiber on microscale must be prior determined. The effective properties of the nanofiber can be determined by homogenization procedure using representative volume element (RVE). A concentric composite cylinder embedded with a caped carbon nanotube represents RVE as shown by Figure 2. A carbon nanotube with a length 2, radii a is embedded at the center of matrix materials with a radii R and length 2L. 

Until now, the macroscopic tribological properties of the nanotubes had not been studied. The only studies carried out used the nanotubes as reinforcement in various matrices diamond thin film [87], polyimide [88], Ni [89], Ni-P [90], carbon/carbon composites [91] and alumina [92, 93]. These composite coatings present a better wear resistance and a lower friction. In nanotribology, Ohmae et al. studied friction of a gold tip on a nanotube forest. The friction coefficient obtained was high (1.2 to 1.5) and independent of humidity [94]. A very weak adhesion of the tip on the nanotubes was observed. During friction, no distortion of the nanotubes intervenes and there is no transfer of nanotubes on the tip. Recently, Miyoshi et al. 

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