Carbon nanotube–polymer composites: Chemistry, processing, mechanical and electrical properties

https://tore.tuhh.de/bitstream/11420/394/1/Article_5._free.pdf

A review and analysis of electrical percolation in carbon nanotube polymer composites

This paper reviews recent studies conducted on carbon nanotube/polymer composites. Carbon nanotubes are promising new materials for blending with polymers with potential to obtain low-weight nanocomposites of extraordinary mechanical, electrical, thermal and multifunctional properties. The size scale, aspect ratio and properties of nanotubes provide advantages in a variety of applications, including electrostatically dissipative materials; advanced materials with combined stiffness, strength and impact for aerospace or sporting goods; composite mirrors; automotive parts that require electrostatic painting and automotive components with enhanced mechanical properties. The various processing methods for producing these nanocomposites are discussed, in particular melt mixing, solution processing and in-situ polymerization. Some key results are summarized, relating to the mechanical, electrical, thermal, optical and surface properties. Finally, the challenges for the future are discussed in terms of processing, characterization, nanotube availability, nanotube tailoring, and the mechanisms governing the behavior of these remarkable nanoscale composites. Polym. Compos. 25:630–645, 2004. © 2004 Society of Plastics Engineers.

Big returns from small fibers: A review of polymer/carbon nanotube composites

Field electron emission from vertically well-aligned zinc oxide (ZnO) nanowires, which were grown by the vapor deposition method at a low temperature of 550 °C, was investigated. The high-purity ZnO nanowires showed a single crystalline wurtzite structure. The turn-on voltage for the ZnO nanowires was found to be about 6.0 V/μm at current density of 0.1 μA/cm2. The emission current density from the ZnO nanowires reached 1 mA/cm2 at a bias field of 11.0 V/μm, which could give sufficient brightness as a field emitter in a flat panel display. Therefore, the well-aligned ZnO nanowires grown at such low temperature can promise the application of a glass-sealed flat panel display in a near future.

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Field emission from well-aligned zinc oxide nanowires grown at low temperature

Mechanical and electrical properties of a MWNT/epoxy composite

The purposes of the present work were to develop the fabrication techniques of a thin film electron emitter. Devices with good reproducibility and stability were obtained when carbon films were deposited on a Corning 7059 glass rubbed with emery paper (#1000), and were heat-treated at 600°C in high vacuum.When the input power density to the devices attained to about 2.4×108 W/cm3, the carbon films were locally broken due to the joule heating and electron emission from the devices became to be detected. The I-V characteristics after the forming were similar to those of the electroformed MIM type devices, and the emission efficiencies were (26) ×10-4.

Electroforming and Electron Emisson of Carbon Thin Films

Various novel photo-physical properties such as a drastic photoluminescence quenching and photoconductivity enhancement and a photo-induced enhancement of low-field microwave absorption due to a highly effective photo-induced electron transfer have been observed in various conducting polymers doped with fullerenes and also acceptor-type molecules and conducting polymers. New types of junction devices utilizing effective charge separation at the interface of conducting polymer/C60, C60-doped conducting polymer/C60 and acceptor type conducting polymer / donor type conducting polymer have been proposed and their novel characteristics have been demonstrated. Novel concepts such as an interpenetrating network, a condensed interface and the effect of introduction of photo-harvesting antenna molecule at the interface have been discussed. Nano-composite films of carbon nanotube (NT) and conducting polymer were prepared. With increasing the volume fraction of NT in conducting polymer the conductivity incr...

Electrical and Optical Properties of Conducting Polymer - Fullerene and Conducting Polymer - Carbon Nanotube Composites

Buckminsterfullerene (C60) is effectively doped in poly(3-alkylthiophene) However, the characteristics of C60-doped poly(3-alkylthiophene) are different from the typical behavior observed in the case of conventional dopants Electrical conductivity of poly(3-alkylthiophene) increases upon C60 doping and decreases again at higher concentration of C60 Its temperature dependence is also anomalous The absorption spectrum changes markedly upon C60 doping ESR linewidth decreases from 71 G to 19 G upon C60 doping Spin density, evaluated by ESR, is enhanced upon C60 doping These doping characteristics are tentatively explained by taking electronic energy diagrams of both poly(3-alkylthiophene) and C60 into consideration

Electrical Conductivity and ESR Spectrum of Buckminsterfullerene-Doped Poly(3-alkylthiophene)

Microstructures of bamboo-like multiwalled carbon nanotubes prepared by pyrolysis of Ni-phthalocyanine are studied by high-resolution transmission electron microscopy. The intershell spacings of graphitic shells in these nanotubes are estimated. From pristine nanotubes with a tube diameter of 40–260 nm, the spacing values of 0.339–0.342 nm are obtained almost independent of their tube diameters. However, after heat treatment at 2800 °C they are reduced to a value equivalent to the interlayer spacing of graphite, and tube walls with a clear polygonal cross section come to be observed. The heat treatment of samples is also a very useful method to prepare metal-free nanotubes. The bamboo-like graphitic shells are interpreted to be determined by a cone-shaped Ni nanoparticle included at the base of the multiwalled carbon nanotube.

Multiwalled carbon nanotubes with bamboo-like structure and effects of heat treatment

The field emission from aligned multiwalled carbon nanotubes prepared by thermal chemical vapor deposition of Fe-phthalocyanine is reported, with emphasis on the current–voltage characteristics and current fluctuation By running of a pristine emitter at high current and/or voltage for a long time, the onset voltage is lowered from 400 to 125 V and the field-enhancement factor increases from 360 to 1110, demonstrating geometrical reconstruction of the nanotube apex Deviation from the Fowler–Nordheim relation is caused at a constant local electric field of ∼4×103 V/μm and is related to high-field conditioning Electron emission current under a high current density condition (>10 mA/cm2) is stable and noiseless The reason for current noise in the lower current density is discussed

Hisashi Araki

Papers

Electroforming and Electron Emisson of Carbon Thin Films

Electrical and Optical Properties of Conducting Polymer - Fullerene and Conducting Polymer - Carbon Nanotube Composites

Electrical Conductivity and ESR Spectrum of Buckminsterfullerene-Doped Poly(3-alkylthiophene)

Multiwalled carbon nanotubes with bamboo-like structure and effects of heat treatment

Field emission from aligned carbon nanotubes prepared by thermal chemical vapor deposition of Fe-phthalocyanine