In
this paper, a special dielectric property with tailorable negative
permittivity is attained in the polyaniline assisted magnetic ultrafine
barium ferrite (BaFe12O19) nanorods reinforced
epoxy metacomposites. The ultrafine BaFe12O19 nanorods have been prepared through a citrate assisted sol–gel
method and a self-propagating combustion combined with high temperature
annealing. A thin polyaniline (PANI) layer is introduced on the surface
of BaFe12O19 nanorods by in situ polymerization
method under the sonication combined with the mechanical stirring
in order to improve the dispersion quality and interfacial compatibility
between BaFe12O19 and epoxy matrix. The enhanced
tensile strength with maximum value of 90.7 MPa for the cured epoxy
nanocomposites filled with 10 wt % loading of PANI modified BaFe12O19 (s-BaFe12O19) nanorods
was obtained in the tensile tests compared with that of the cured
pure epoxy (75.2 MPa) and cured epoxy nanocomposites filled with the
same loading of bare BaFe12O19 (u-BaFe12O19) nanorods (74.4 MPa). In the cured s-BaFe12O19/epoxy nanocomposites, the uniform BaFe12O19 distribution has been observed by scanning electron
microscope (SEM), which contributes to the improved tensile strength.
A negative real permittivity is achieved in both of u-BaFe12O19 and s-BaFe12O19/epoxy nanocomposites
at the low frequency range (∼103 Hz). After further
increasing frequency, the real permittivity was changed from negative
to positive. The permittivity has no u-BaFe12O19 loading dependency for the u-BaFe12O19/epoxy
nanocomposites. However, it is decreased with increasing s-BaFe12O19 loadings in the s-BaFe12O19/epoxy nanocomposites, which exhibits the component rather than structure
controlled epoxy metacomposites.
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