Carbon nanotubes room temperature electrical

Figure 3.4 Room temperature electrical conductivity of collagen/guar gum/XCNT hybrid nanobiocomposite films as a function of XCNTs. BCNT, brush-like carbon nanombe FWCNT, few-waUed carbon nanotube XCNT.

Pan and co-workers [91 ] used in situ polymerisation of pyrrole on to carbon nanotubes to produce carbon nanotube-pyrrole composites and showed that the electrical conductivity of the composites at room temperature was higher than that of pure PPY. Pure polypyrrol, carbon nanotubes and the nanocomposites all exhibited semi-conductive behaviour. Polymers studied included HOPE [92], PP [93], epoxy resin [94], PU [95], PEA [96], poly-p-phenylene vinyl ether [97], PEEK [98], PC [99], PEI [100], polylactide [101] and PI [102]. 

The use of organic nanofillers allows the reduction of the filler content required to achieve high thermal conductivity. In particular, multi-walled carbon nanotubes (MWCNTs), with their one-dimensional structure, high aspect ratio and superior thermal conductivity (3000 W/mK for an individual MWCNT and 200 W/mK for bulk MWCNTs at room temperature (Yang et al., 1991)) have recently attracted great attention in the scientific world. The influence of different carbon nanotube types, particle content, interfacial area, surface functionalization and aspect ratio on the electrical and thermal conductivity of epoxy resins has been investigated (Gojny et al., 2006). 

Yan et al. (2011) prepared rigid PU nanocomposite foams reinforced with variable concentrations of carbon nanotubes for long-term use electrical conductive components. Particularly, for a 2 wt% CNT content, rigid PU foams presented around a 30% increase in compression properties and a 50% increase in storage modulus, both measured at room temperature, when compared to the unfilled PU foam, thus demonstrating the effective mechanical reinforcement effect that low amounts of carbon nanotubes have on PU foams. 

The intermediate 19 was synthesized by nucleophilic addition of alkynes to a-hydroxy ketone in the presence of DABCO in dichloromethane at room temperature for 10 minutes. The intermediate 19 provides the furan in the presence of CuO/CNT catalyst in presence of acetic acid in DMF at 60 °C (Scheme 44). During optimization of the reaction conditions it has been foimd that in the presence of several copper (II) and copper (I) salts such as CuBr2, CuCl2, Cu(OAc)2, CuO, CuI, CuBr, CuCl, the reaction gives yields of less than 10%. But in case of CuO/CNT the reaction provides product in higher yield (greater than 60%) in acetic acid. This indicates that the excellent electrical conductivity of carbon nanotubes might promote the cyclization reaction. 

Chemical sensors the electrical properties of carbon nanotubes (single wall or multiwall) were recently demonstrated to be very sensitive to chemical composition variations of the surrounding atmosphere at room temperature. This very interesting property would allow an iimovative chemical sensor to be designed with high sensibility and capability to detect various chemical substances. 

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