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Bi S.,PLA Second Artillery Engineering University | Bi S.,Beijing composite materials company | Su X.-J.,PLA Second Artillery Engineering University | Hou G.-L.,PLA Second Artillery Engineering University | And 4 more authors.
Xinxing Tan Cailiao/New Carbon Materials | Year: 2014

Multi-wall carbon nanotubes (MWCNTs) were oxidized by soaking in mixed acids. Their microstructure and composition were characterized using transmission electron microscopy, atomic force microscopy, Raman spectroscopy and infrared spectroscopy. The influence of soaking time on microstructure and dispersibility of the cut MWCNTs in aqueous solution was investigated. Results show that the MWCNTs were oxidized at defect sites by the mixed acids and converted from highly tangled ropes into short, open-ended nanotubes with lengths of 200-1 500 nm. The isoelectric point was reduced from 4.5 to 3.5 due to hydroxyl and carboxyl groups on the surface and the open ends of the cut MWCNTs. The aggregation experiments and UV-vis absorbance spectra revealed that the cut MWCNTs can be best dispersed in an aqueous solution containing 0.1 wt.% of sodium dodecyl-benzenesulfonate when sonicated at a pH value of 2 for 40 min.

Bi S.,HIGH-TECH | Bi S.,Beijing Composite Materials Company | Bi S.,Beijing Institute of Technology | Ma L.,HIGH-TECH | And 5 more authors.
Advanced Powder Technology | Year: 2014

Carbon nanotube (CNTs) based heterostructures, such as CNT/metal, CNT/polymer, CNT/semiconductor, are attractive for the combined properties and unique applications in cutting-edge electronics and devices. Here in this work, nanostructured beta-silicon carbide (b-SiC)/CNTs heterostructures were synthesized by carbothermal reduction of silica (SiO2) and CNTs with diverse mixing ratios of nC:nSi. Different techniques were carried out for the characterization of the structures and morphologies of the achieved heterostructures, demonstrating dramatic different morphologies which were associated with the different starting ratios of the nC:nSi. The dielectric properties and microwave absorption of wax-based composites were investigated. The parameters for morphologically controllable synthesis and related mechanism for dielectric properties and electromagnetic attenuation were discussed. © 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

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