الفهرس 
Introduction & Literature SurveyOnly 14 pages are availabe for public view
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Abstract
In the present work, silicone rubber-lead oxide composites were prepared with different concentrations of lead oxide (15-42 wt. %) as γ-radiation shields. The radiation shielding properties of silicone rubber-Lead oxide composites (linear attenuation coefficient (µ) and total mass attenuation coefficient (µ/ρ)) have been evaluated using four radioactive point sources (232Th, 137Cs, 60Co and 22Na) in the energy range (238 to 2614keV) and compared with the corresponding theoretical predictions. The experimental values were in general in fair agreement with the values theoretically calculated by means of WinXcom program (version 3.1). The shielding properties were found to be improved with the increase of lead oxide content. The present results of the mass attenuation coefficient at the preferred silicone rubber composite with (35 %) lead concentration compared with the standard shielding concrete represent a strong advantage of rubber composite shield for many applications for its low weight and elasticity.
Furthermore, the effect of both filler content and irradiation dose on the mechanical properties (tensile strength (σR), elongation at break (εR), Young’s modulus (E) and hardness (H)) have been performed. from the obtained results it is found that the mechanical properties (tensile strength (σR), elongation at break (εR), Young’s modulus (E) and hardness (H)) increase with the increase of filler content up to 35% by weight and hereafter decrease It was found that, filler incorporation into the rubber matrix is one of the major factors that improve the physico-mechanical properties. The increase in tensile strength as well as Young’s modulus was attributed to improve interfacial bonding between filler and silicon rubber matrix. The aging behavior (resistance to deterioration) of the prepared rubber compounds due to the prolonged exposure of γ irradiation was estimated by plotting the values of the physico-mechanical properties at different γ-doses which showed significant stabilization against γ radiation. Also, the dependence of the real part of the dielectric constant ε′ and the imaginary part ε″ on both lead oxide concentration and frequency has been experimentally performed and carefully discussed.