The hysteresis loops were recorded using SQUID
magnetometer at temperature 300 K and magnetic field up to 7 T.
Hysteresis loops that were achieved for polymer magnetic
composite materials are shown in Figs. 3-8.
The remanence and coercive force values for polymer
magnetic composites were determined from magnetic hysteresis
loops according. If some magnetic flux remains in the material
even though the magnetizing force is zero (H = 0), the retention of
magnetization in zero is called remanence or residual flux density.
Coercive force (coercivity) is obtained when the magnetic field
required to reduce the external magnetization of a ferromagnetic
substance to zero (B = 0). These two quantities, residual flux
density and coercive force are of great importance in permanent
magnets. Results that were obtained for these measured quantities
are presented in Fig. 9 and Fig. 10.
As can be seen on charts and as it could be expected
remanence increased while coercive force decreased with
increasing volume fraction of magnetic fillers. Moreover results
of remanence and coercive force of polymer composite materials
with isotropic ferrite powders (strontium ferrite and barium
ferrite) had approximately the same results whereas composite
materials with anisotropic filler had much higher values (twice
higher for remanence and about thrice higher for coercive force).
The highest value of remanence is approximately 21 [emu/g]
and was obtained for specimen filled with 35%vol. of anisotropic
powder amount whereas the lowest value of remanence is
13 [emu/g] for 15%vol. of AMM. The highest remanence for
composite material with 35%vol. of strontium ferrite is