Nanocomposites electrical conductivity

Shen et al. [75] measured the electrical conductivity of polyethylene/maleic anhydride-grafted polyethylene/graphite nanocomposites. Electrical conductivity and morphology were influenced by the polymer preparation method and could be explained in terms of percolation theory. 

Polyurethane nanocomposites Electrical conductivity surface resistivity 22... 

There are several reports of Ag nanocomposites with conducting polymers like polyaniline [38] and polypyrrole [39]. However, electrical conducting properties of green metal - starch... 

Electrical conductivity measurements revealed that ionic conductivity of Ag-starch nanocomposites increased as a function of temperature (Fig.l7) which is an indication of a thermally activated conduction mechanism [40]. This behavior is attributed to increase of charge carrier (Ag+ ions) energy with rise in temperature. It is also foimd to increase with increasing concentration of Ag ion precursor (inset of Fig.l7). This potentiality can lead to development of novel biosensors for biotechnological applications such as DNA detection. 

Alignment of CNTs markedly affects the electrical properties of polymer/CNT composites. For example, the nanocomposites of epoxy/MWCNTs with MWCNTs aligned under a 25 T magnetic field leads to a 35% increase in electric conductivity compared to those similar composites without magnetic aligned CNTs (Kilbride et al., 2002). Improvements on the dispersion and alignment of CNTs in a polymer matrix could markedly decrease the percolation threshold value. 

Carbon materials provide electrical conduction through the pi bonding system that exists between adjacent carbon atoms in the graphite structure [182]. Electrical properties of nanocomposites based on conducting nanofillers such as EG [183-187], CNTs [188-190], and CNFs [191], dispersed in insulating polymer matrix have found widespread applications in industrial sectors. 

Metal-organic nanocomposite materials are interesting from the point of view of the bottom-up approach to building future electronic devices. The ability of the organic parts of the composite materials to identify and latch on to other organic molecules is the basis for the possible self assembly of nanoscale devices, while the metallic components provide mechanical robustness and improve the electrical conductance. 

Flahaut, E., Peigney, A., Laurent, C. et al., Carbon nanotube-metal-oxide nanocomposites microstructure, electrical conductivity and mechanical properties, Acta Mater., 2000, 48 3803. 

We measured the electrical conductivity of Pt-C nanocomposites using two-point measurements. In a representative example the NP-polymer hybrid had a conductivity of 2.5 mS cm-1, which increased to 400 S cm-1 upon pyrolysis. Despite the presence of carbon, to the best of our knowledge this value represented the highest electrical conductivity yet measured for ordered mesoporous materials derived from block copolymers. This discovery creates a potential pathway to a new class of ordered mesoporous metals made from nanoparticles of different elements and/or distinct compositions. Such nano-heterogeneous mesoporous metals may have a range of exceptional electrical, optical, and catalytic properties. 

Nanocomposite coatings - nanoparticles giving improved properties compared to microparticles e.g. thermal and electrical conductivity, transparency, uniformity, low friction. 

Keywords nanocomposites, dispersion, aspect ratio, in-situ, melt, morphology, tensile properties, glass transition temperature, degradation, functionalization, electrical conductivity, resistivity. 

Figure 2.15. Electrical conductivity of polycarbonate nanocomposites by using different fractions of either unmodified nanotubes or H202 treated nanotubes. Reproduced from reference 54 with permission from Elsevier.

Benoit et al. (41) obtained electrically conductive nanocomposites by dispersing SWCNT and PMMA in toluene, followed by drop casting the mixture on substrates. Thin films of SWCNT-PMMA composites for different CNT concentration were produced by spin casting by Chapelle et al. (54) and Stephan et al. (55). They characterized these nanocomposites by Raman spectroscopy to study interactions between nanotubes and PMMA and found that PMMA tends to intercalate between the CNTs thereby increasing the distance between the nanotubes in the film. 

This paper represents an overview of investigations carried out in carbon nanotube / elastomeric composites with an emphasis on the factors that control their properties. Carbon nanotubes have clearly demonstrated their capability as electrical conductive fillers in nanocomposites and this property has already been commercially exploited in the fabrication of electronic devices. The filler network provides electrical conduction pathways above the percolation threshold. The percolation threshold is reduced when a good dispersion is achieved. Significant increases in stiffness are observed. The enhancement of mechanical properties is much more significant than that imparted by spherical carbon black or silica particles present in the same matrix at a same filler loading, thus highlighting the effect of the high aspect ratio of the nanotubes. 

The electrical conductance of carbon nanotubes is sensitive to the chemical environment of the tubes. A large difference in the electrical conductance is observed for the carbon nanotubes in the presence of air and oxygen atmosphere. " " It is possible to tune the electrical conductance of carbon nantubes reversibly using adsorbent gas molecules. The carbon nanotubes were also used to increase the conductance of a conjugated polymer for the development of electroluminescence polymer-nanocomposites. " ... 

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