Graphite nano-tubes

There has been a trend in recent years to move towards the electrostatic deposition of paints for exterior automotive applications. Reasons for this include improved paint transfer efficiency. Normally, plastic parts need to be painted with a conductive primer prior to the electrostatic painting of base and clear coats. One of the most recent developments in the area of external automotive applications is that of intrinsically conductive resins for electrostatic painting. Currently there are commercial applications for body panels that utilize PPE/PA that contains carbon black as the conductive component. In the USA, a mirror shell application uses PPE/PA where the conductivity is achieved through the incorporation of graphite nano-tubes. 

Report of graphitic carbon nano-tubes by Sumio Iijiama of NEC (SWCNT had been reported earlier but remained unnoticed at the time)... 

The recent use of the transmission electron microscopy of high resolu tion at the in situ condition at large enough pressure of methane resulted in the direct observation of the metal nanoparticle liquefaction at the cata lytic methane pyrolysis. Thus, the formation of carbon fibers and nano tubes often results from fluidization of the catalyticaUy active phase via its oversaturation with carbon at the catalyst operation. This may happen to a variety of processes when the deposition of graphitized carbon is pre ceded by the primary atomic or another energy saturated carbon species formed on the surface of the catalyticaUy active metals (see Figure 5.2). Supposedly, the formation of the very specific structures of the carbon fil ament, like the so caUed fishbone structure (see Figure 5.3B), may be... 

Brunauer-Emmet-Teller (BET) estimated surface areas [23], For example, from Figure 5.9, graphite felt electrodes show poor volume-normalized ORR current density compared to carbon nanofibers and multiwaUed carbon nanotube (MWCNT)-based electrodes. However, the results also reveal that CNTs and porous carbon tubes exhibit dramaticaUy lower ORR current densities when normalized to B ET surface area, while graphite felt electrodes perform better, perhaps indicative of agglomeration of the carbon tubes, preventing enzyme adsorption over the entire area. Further research on methods to permit dispersion of nano-tubes, while retaining electrical conductivity and adsorption of enzymes oriented for DET, is warranted. 

Figure 14.2 Some representative sp carbon materials (a) graphite (b) Ceo (c) single-walled carbon nano tubes (d) multi walled carbon nanotube (e) carbon nanofibers grown by plasma-enhanced chemical vapor deposition.

Carbon nanotubes (CNTs) are seamless cylindrical graphitic nanofibers made of sp carbon atoms. A carbon nanotube may consist of a single graphitic sheet [single-walled carbon nanotubes (SWCNTs) [8] as shown in Figure 14.2(c)] or multiple concentric graphitic sheets [multi walled carbon nano tubes (MWCNTs)... 

Carbon is the atom of the periodic table that forms the greatest number of compounds. Pure carbon may also form large molecules and crystallize into a number of allotropic forms, such as 35, C o, and C70 from the large fullerene family, nano tubes (a tube-like form of a fullerene), graphite, and diamond. These substances have widely different conductivity properties. 

There are a number of products which are described as nano-fibres or nano-tubes. These are mainly carbon or metallic in nature and principally intended for electrical applications, where they produce conductivity at significantly lower volume fractions than more conventional conductive fillers. Most of these products are several tens of nanometers in diameter and so are outside of the definition of nano-particles adopted for this discussion. Pyro-graphitic fibres are a typical example. Their diameter is from 60-200 nm, with specific surface areas of 100-20 mVg, respectively [13]. 

Carbon nanotubes are hollow carbon structures as a graphite sheet wound cylindrically. Their diameter is few A to 100 nm. Since the aspect ratio is very large, the material has a fibrous form. Carbon nanotubes having one graphite layer are called SWCNT (Single-Walled Cabon Nanotube). Other carbon nano tubes are called MWCT (Multiwalled Carbon Nano tube) (lijima 1991 Saito 2003 Fan et al. 1999 Nakayama 2002 Akita et al. 2001). 

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