Search

The in-plane shear property of carbon fiber laminates is one of the most important structural features of aerospace and marine structures. Fiber-matrix debonding caused by in-plane shear loading is the major failure mode of carbon fiber composites because of the stress concentration at the interfaces. In this study, carbon nanotube mats (CNT mat) were incorporated in two different types of carbon fiber composites. For the case of woven fabric composites, mechanical interlocking between the CNTs and the carbon fibers increased resistance to shear failure. However, not much improvement was observed for the prepreg composites as a result of incorporation of the CNT mats. The reinforcement mechanism of the CNT mat layer was investigated by a fractographic study using scanning electron microscopy. In addition, the CNT mat was functionalized by three different methods and the effectiveness of the functionalization methods was determined and the most appropriate functionalization method for the CNT mat was air oxidation. [ABSTRACT FROM AUTHOR]

Abstract: We have, for the first time, fabricated chromium (Cr) carbide nanostructures on multiwalled carbon nanotubes (MWCNTs) in a MWCNT–copper (Cu) composite by adding small amounts of Cr. A single nanocrystal of carbide was epitaxially grown on the sidewall of chemically treated MWCNTs through the diffusion of solute Cr atoms to defects in the MWCNTs. Carbide has an island-shaped morphology with a maximum size of several hundred nanometers. The phase of the generated Cr carbide nanostructures was mostly Cr7C3, as determined by electron beam diffraction using the nanobeam diffraction mode of a transmission electron microscope. In particular, the Cr carbide nanostructures formed at radially unzipped sites were connected to the outermost wall and some inner walls of the MWCNTs. This is expected to increase the load-bearing capacity of the MWNCTs because the inner walls contribute to the load transfer, which is very effective for improving the mechanical and thermomechanical properties of the composites. [Copyright &y& Elsevier]

Composites were prepared by the electrostatic interaction between carboxylated multi-walled carbon nanotubes (c-MWNTs) and either cadmium telluride (CdTe) or cadmium selenide (CdSe) nanoparticles. Multi-walled carbon nanotubes (MWNTs) were oxidized by an aqueous acid mixture, and both the CdTe and CdSe nanoparticles were stabilized by 2-(dimethylamino) ethanethiol hydrochloride in water to develop negatively and positively charged outer surfaces, respectively. Optical properties were investigated by UV/Vis and photoluminescence (PL) analyses. CdX (X = Te, or Se) nanoparticles showed emissions at the same position regardless of the existence of c-MWNTs. This result suggests that the interaction between CdX and c-MWNTs does not affect the photoluminescence of CdX nanoparticles in their composites. The binding energies and redox potential positions of the CdX nanoparticles in their c-MWNT-CdX composites shifted from those of the pure nanoparticles. These changes indicate that the electron densities on the interfaces of CdX nanoparticles and c-MWNTs were redistributed after the formation of composites due to the strong electrostatic interaction between the components. [ABSTRACT FROM AUTHOR]

Nanocrystalline soft magnetic Fe73Si16B7Nb3Cu1 (at.%) powders were mixed with fine multi-walled carbon nanotube (MWNT) powders and polyurethane based binders. The mixtures were tape-cast, dried and then cold-rolled to form EM wave absorption sheets. The MWNT powders were added to the Fe-based powders up to 1 wt.% to improve the EM wave absorption properties. The processed sheets with 0.5 mm in thickness were cut into toroidal shape to measure the S-parameter, permeability, permittivity, and power loss at the high frequency of 10 MHz to 10 GHz. As a result, improved absorption properties were obtained from the sheets incorporating MWNT. The results were caused by the increase of dielectric loss of the absorption sheets, which was due to the addition of MWNT powder inducing a notable increase in complex permittivity. [ABSTRACT FROM AUTHOR]

We investigated a facile method for producing conductive polymer composites for the construction of microelectrodes already integrated into microsystems, as promising for microfluidic application. The porous morphology, high conductivity and large surface area of the composites which in turn influences its electrochemical performance can be simultaneously achieved by optimizing the composition and nanostructure of the conductive material and polymer. Three different carbon materials (i.e. graphite, graphene, carbon nanofibers) were combined with poly(methyl methacrylate) (PMMA) polymer and all the subsequent carbon-PMMA composites were assessed electrochemically using cyclic voltammetry in the presence of ferrocyanide as a model redox analyte. The results indicated that graphite was well dispersed and incorporated throughout the composite to form a highly electrically conductive network that proved to be even better than the graphene sheets and carbon nanofibers. In order to demonstrate the ease of composite fabrication with tailored properties for intended analytical applications, the optimal graphite-PMMA composite was further investigated to incorporate Prussian blue, as a model mediator for H 2 O 2 detection. • Carbon materials (graphite, graphene, CNF) were comparatively composited with PMMA. • The PMMA-based composites are evaluated as integrated electrodes into PMMA microchip. • The composite electrodes were assessed electrochemically in the presence of ferrocyanide. • Optimal graphite/PMMA/Prussian blue composite exhibited high electroactivity toward H 2 O 2. [ABSTRACT FROM AUTHOR]