الفهرس 
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Abstract
Nanodielectrics based on metal oxide nanoparticles (NPs) exhibit significant improvement in dielectric performances. This thesis was carried out to study the electric and dielectric properties of nanodielctrics based on two different host insulating polymers namely polyvinyl chloride (PVC) and high density polyethylene (HDPE). Zinc oxide nanoparticles (ZnO-NPs), with wurtzite structure, and iron oxide NPs (Fe2O3), with rhombohedral structure, were synthesized using sol gel route and were used as nanofiller of the investigated insulating polymers. Microstructure and morphology of the synthesized NPs were examined using X-ray diffraction (XRD), Fourier transform infrared (FTIR), high resolution transmission electron microscopy (HRTEM) and field emission scan electron microscopy (FESEM) . The crystallite sizes and lattice parameters of NPs were determined using XRD results. PVC nanocomposites were fabricated using solution casting technique with different procedures. However, HDPE nanocomposites were fabricated using melt blending technique. The surface and cross section morphology of the fabricated nanocopmposites were examined using FESEM. The DC dielectric breakdown strength of the fabricated nanocomposites were studied. The real part of the permittivity ( ) and the loss tangent ( tan ) dependency on filler concentration were studied under different applied frequency values from 1 kHz to 1 MHz. Comparison study using EMTP/ATP package was carried out between conventional cable based on the original material HDPE and suggested shield, HDPE/1.0 wt% ZnO, of insulated cable.