The Preparation And Characterization Of Nano-fillers/Polymer Composites For Microwave Absorption

The problem of electromagnetic radiation becomes more serious during thedevelopment of technology and electronic industry. Novel microwave absorbingcomposites with magnetic loss and dielectric loss at the same time become importantin research now.Synthesis methods of Zn powder/PVDF composites, NiCuZn ferrite and carbonnanotubes (CNTs)/ferrite/PVDF composites were studied in this thesis. Structure,dielectric capability, resistance rate and magnetic capability of these composites wereinvestigated. The relationship between different synthesis methods and capability wasstudied.Zn powder/PVDF composites with high dielectric constant were fabricated bywater-deposition method and film forming method. Dielectric constants of thesecomposites made by film forming method have a good match with theory value.There are some problems of oxidation protection in water-deposition processing,which made a deviation from theory value.NiCuZn ferrite with good dispersion and single crystal structure were fabricatedby hydrothermal method. Hydrothermal reaction time and pH value were investigated.The results show that 4 hours is long enough for hydrothermal reaction to fabricateferrites with good capability. Single spinel structure with good crystallization can beformed under the condition of pH=9.In CNTs/ferrite/PVDF composites fabricated by co-hydrothermal method, CNTscan be contained by ferrite more easily than in those fabricated by simple mixedmethod. Dielectric capability of CNTs/ferrite/PVDF three-phase composite is moreexcellent than CNTs/PVDF or ferrite/PVDF two-phase composite with the same massconcentration of CNTs or ferrite. The dielectric constant of the three-phase compositewith 10% mass concentration of CNT is over 500, and tanδE is over 10 in the lowfrequency range.