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Structure and Microwave Absorption Properties of Poly（Ppyrrole） Coated Fe3O4/Multiwalled Carbon Nanotube Composites

Author: LiShangWen
Tutor: CaiWei
School: Harbin Institute of Technology
Course: Materials Physics and Chemistry
Keywords: conductive polyppyrrole chemical oxidation method Fe3O4/MWNTs compounds microwave absorption properties
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 222
Quote: 3
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Abstract


Composites of polypyrrole（PPy） coated Fe3O4/multiwalled carbon nanotube was synthesized on the surface of Fe3O4/MWNTs in situ using chemical oxidation polymerization method with FeCl3 as oxidants, NaDBS as dopant. The morphology, structure, electrical conductivity, magnetic properties and microwave absorbing properties were studied by scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, Fourier transform infrared （FT-IR） spectroscopy, X-ray diffraction （XRD）, four-probe conductivity measurement method, AC susceptibility and vector network analyzer. Clarify the effect of process parameters on the morphology, structure, electrical conductivity, magnetic properties and microwave absorbing properties.The experiment results show that the content of Fe3O4/MWNTs have played a significant role on the morphology of polyppyrrole coated Fe3O4/MWNTs composite. When having more ontent of pyrrole monomer （Fe3O4/MWNTs:Py≥1:2）, the pyrrole monomer is tent to polymerize on the surface of Fe3O4/MWNTs compounds. Thus,the prepared polypyrrole coated Fe3O4/MWNTs composite possesses coaxial structure. With the content of pyrrole monomer increasing,the polypyrrole coated thickness became increasingly thick. When having less content of Fe3O4/MWNTs （Fe3O4/MWNTs:Py≤1:4）, prepared polypyrrole coated Fe3O4/MWNTs composite was coralline structure. Dopant of NaDBS also have affects on the morphology of the polypyrrole coated Fe3O4/MWNTs composite. With the content of NaDBS is decreased,the polypyrrole coated Fe3O4/MWNTs composite with coaxial structure is easier to be prepared.The polypyrrole coated Fe3O4/MWNTs composite with coaxial structure have higher conductivity than polypyrrole coated Fe3O4/MWNTs composite with coralline structure, because the composites have the structure of conductive net and making the electron transport easy. The content of Fe3O4/MWNTs and Fe3O4 have a significant impact on the saturation magnetization of polypyrrole coated Fe3O4/MWNTs composite, with the content of Fe3O4/MWNTs and Fe3O4 increasing, the saturation magnetization of polypyrrole coated Fe3O4/MWNTs composite is increaseed.The test results of absorbing properties show that the absorption properties of polypyrrole coated Fe3O4/MWNTs composites with coralline structure was better than polypyrrole coated Fe3O4/MWNTs composites with coaxial structure. When Fe3O4/MWNTs:Py = 1:4, Fe （acac）3: MWNTs = 4: 1, NaDBS:Py = 1:1, the Permittivity and the Permeability of polypyrrole coated Fe3O4/MWNTs composite matched best. The polypyrrole coated Fe3O4/MWNTs composite had strongest absorption capacity with the maximum absorption rate of 29.09 dB,and the absorption rate was greater than 10 dB within the frequency of 11.3617.18 GHz.

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