Synthesis, characterization and application of doped-polyaniline (pani) nanocomposites for microwave absorption / Koh Yen Nee
Conducting polymer nanocomposites containing aniline (Ani) monomer and hexanoic acid (HA) dopant has been synthesized by template free method. Dielectric (titanium dioxide (TiO2)) and magnetic (iron (III) oxide (Fe3O4), carbon nanotubes (CNT), graphene and etc.) materials have been added to impro...
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| Format: | Thesis |
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2014
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| Online Access: | http://studentsrepo.um.edu.my/4777/ http://studentsrepo.um.edu.my/4777/1/Dissertation_KOH_YEN_NEE_(SGR110071)_Final.pdf |
| Summary: | Conducting polymer nanocomposites containing aniline (Ani) monomer and
hexanoic acid (HA) dopant has been synthesized by template free method. Dielectric
(titanium dioxide (TiO2)) and magnetic (iron (III) oxide (Fe3O4), carbon nanotubes
(CNT), graphene and etc.) materials have been added to improve the dielectric and
magnetization property of the nanocomposites. Fourier Transform Infra Red (FTIR),
Ultraviolet-visible (UV-vis), and X-ray diffraction (XRD) analyses have confirmed the
chemical structure of the doped-polyaniline (PAni) nanocomposites. Morphology study,
thermal behavior, electrical conductivity and magnetic behavior of the nanocomposites
have been investigated by Field Emission Scanning Electron Microscope (FESEM),
Thermal Gravimetric Analyzer (TGA), resistivity meter and vibrating samples
magnetometer (VSM), respectively. Microwave absorption study was carried out by
Microwave Vector Network Analyzer (MVNA) from 0.5 to 18 GHz. In this research
study, four types of PAni nanocomposites were prepared namely PAni/HA/TiO2/Fe3O4
nanocomposites (with and without chemical treatments), PAni/HA/TiO2/MWNT
nanocomposites (different diameter and length of MWNT), PAni/HA/TiO2/DWNT
nanocomposites (different contents of u-DWNT and c-DWNT) and
PAni/HA/TiO2/GNP nanocomposites (different contents of GNP). In general, high
electrical conductivity, dielectric permittivity and magnetic permeability are the few
factors that will contribute to a better microwave absorption property of a material.
Among all PAni nanocomposites, PAni/HA/TiO2/MWNT nanocomposites with MWNT
(D = 10-20 nm, l = 5-15 μm) possesses the highest reflection loss (RL = -58 dB) at 7
GHz due to the high heterogeneity and high μrʹ′ and μrʹ′ʹ′. This significantly induces the
space charge polarization and eddy current along the PAni backbone. Finally, it
indicates the strongest absorption. This material is potentially applied as a good
iv
microwave absorber in computer, which operate at 7 GHz. However,
PAni/HA/TiO2/GNP nanocomposites with 40 % of GNP possesses the poorest
microwave absorption with RL of -6.6 dB due to the lower value of μrʹ′ and μrʹ′ʹ′ and the
absent of the nanorods/nanotubes (without heterogeneity). Thus, it significantly
impedes the interaction between PAni and GNP, and eventually leads to the weakest
microwave absorption. |
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