الفهرس 
CHAPTER 1: INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
In recent years, polymer blend technology has attracted attention. Polymer blending technology can develop a wide range of materials with improved electrical, mechanical, thermal and other properties. Therefore, dielectric properties of unfilled as well as nanofilled polystyrene-silicone rubber (SiR) blends are evaluated in this thesis. Accordingly, the preparation of polystyrenesilicone rubber blends is carried out considering three different concentrations of polystyrene (3, 7 and 10 %wt). Also, the preparation of polystyrene-silicone
rubber nanocomposites is carried out considering different two types of
nanoparticles. These nanoparticle types are TiO2 and SiO2 with the same average
particle size of 20 nm. Different nanoparticle concentration levels of 1.5, 2 and 3 %wt are studied. The effect of thermal aging on the dielectric properties of unfilled as well as nanofilled polystyrene-silicone rubber samples is evaluated. The samples are subjected to thermal aging for two months at a temperature of 130 oC. The average breakdown strength as well as the breakdown strength at 10% and 50% probabilities is evaluated before and after the thermal aging process. The dielectric response includes relative permittivity and dissipation factor which measured and evaluated under thermal aging. The obtained results show that adding small amount of polystyrene to silicone rubber improves its dielectric properties. Finally, adding small amounts of TiO2 and SiO2 nanoparticles to polystyrene-silicone rubber blends give more improvements in its dielectric properties.