Nanocomposites electrical properties

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. 

Huang, Q. and Gao, L., Manufacture and electrical properties of MWCNT/BaTi03 nanocomposite ceramics , J. Mater. Chem., 2004, 14, 2536-2541. 

Jiang, L. and Gao, L., Carbon nanotubes-magnetite nanocomposites from solvothermal processes formation, characterization, and enhanced electrical properties , Chemistry of Materials, 2003, 15, 2848-2853. 

Carbon nanotubes represent high potential fillers owing to their remarkably attractive mechanical, thermal and electrical properties. The incorporation of nanotubes in the polymer matrices can thus lead to synergistic enhancements in the composite properties even at very low volume fractions. This chapter provides a brief overview of the properties and synthesis methods of nanotubes for the generation of polymer nanocomposites. 

Nanotube nanocomposites with a large number of polymer matrices have been reported in the recent years. The composites were synthesized in order to enhance mechanical, thermal and electrical properties of the conventional polymers so as to expand their spectrum of applications. Different synthesis route have also been developed in order to achieve nanocomposites. The generated morphology in the composites and the resulting composite properties were reported to be affected by the nature of the polymer, nature of the nanotube modification, synthesis process, amount of the inorganic filler etc. The following paragraphs review the nanocomposites structures and properties reported in a few of these reports and also stress upon the future potential of nanotube nanocomposites. 

It is difficult to fully utilize the mechanical or electrical properties of CNTs in their polyurethane nanocomposites due to the difficulty... 

Due to unprecedented mechanical, electrical and chemical properties, CNTs have been considered as an ideal material for various applications as well as for new fundamental investigations (1,2). In this review chapter, we will only discuss mechanical and electrical properties. In most composite structures, nanotubes are used as mechanical reinforcing agents or conductive fillers. This is also the case of PVA/nanotubes nanocomposites. 

Feng and coworkers prepared nanocrystalline tin oxide on monolithic mesoporous silica starting from Sn(acac)2Cl2 by simple immersing of the substrate in the precursor solution. Heat treatment (300-600 °C) leads to nanocomposites with a large specific surface area. The electrical properties of these nanocomposites were also investigated. The authors found an inverse correlation between the precursor concentration and the electrical resistivities of the samples. ... 

The electric properties of soft ferromagnetic nanoparticles in an insulating matrix strongly depend on the concentration of a metallic filler x and are varied between properties of the matrix and those of the filler. In binary nanocomposites a critical concentration (percolation threshold Xq) is reached when a continuous current-conducting cluster of the filler particles is formed through out the sample. 

Because of the small size of nanotubes (<1 nm) and their excellent mechanical and electrical properties (depending on the hexagonal lattice and chirality), they have been recognized as ideal for nanocomposite structures. The relative tensile strength of theses structures can be as high as 200 GPa, with Young s moduli as high as 1 TPa. 

A chapter focusing on the use of nanocomposites in electrochemical devices is presented by Schoonman, Zavyalov, and Pivkina. A wide range of metal (metal ox-ide)/polymer nanocomposites has been synthesized using Al, Sn, Zn, Pd, and Ti as a metal source and poly-para-xylylene (PPX) as a polymeric matrix. The properties of the nanocomposites were studied by comparing structure, morphology, electrical properties, oxidation kinetics, and electrochemical parameters. 

It was revealed that at deposition of the nanocomposite films in the Ar + O2 gas mixture the region of the superparamagnetic state was expanded far beyond percolation threshold %c determined from the electrical properties of the films deposited in pure Ar. An inductive contribution in equivalent circuits of the studied films shows that the currentconducting routes within the film bulk look like a system of nanocoils embedded in the alumina matrix. 

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