الفهرس 
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Abstract
Influence of Uniaxial Stress and Gamma Radiation on the Physical Properties of Conductive Rubber Blends for Radiation Safety Requirements
HOWAYDA GALAL ABDEL-MONIUM TAHA
Radiation Safety Department, NCNSRC, Atomic Energy Authority, Cairo, Egypt
The mixing of polymers has become commercially and technologically more important than the fabrication of homopolymers and copolymers in the last decade. Blending allows one to create new materials from the wide range of existing materials with specific properties for the desired application at low cost. Preparation and physical properties of EPDM, BR and their blends prepared by conventional mixing process with the addition of carbon black (HAF- black) have been investigated. This was to provide additional information about the nature and extent of intermolecular interaction and whether the addition of both HAF-black and BR to EPDM enhances its degradability or crosslinkage property of this polymer, moreover, to test these blends for the use of irradiation resistance materials.
The possibility of ohmic conductions as well as space charge limited conduction is ruled out from the observed behavior of the I-V characteristics. The linear dependence for samples loaded with 40 and 50 HAF- black of ln on E1/2 indicates the presence of Poole- Frenkel mechanism for all EPDM/BR blends except other loaded samples with HAF lower than 40 phr. Moreover, the percolation concept was tested and found to be hold true for EPDM/BR and HAF- black plays the role of conductive particles. The real ` and imaginary `` components show simple frequency dispersion at all blend ratios. Effective medium theory is used successfully to describe this dependence.
The effect of static cyclic strain on the electrical resistivity, , of 40 and 50 HAF-loaded EPDM/BR blends was studied. A large fluctuation of upon loading and unloading were recorded and ascribed to breakdown and alignment of the filler chains in the direction of strain.
Finally, the effect of -irradiation dose in the dose range (0-100 KGy) was elucidated for 50 HAF loaded EPDM/BR blends searching for a proposed sample for irradiation resistance dose. Sample EPDM/BR 0/100 loaded with 50 phr of CB is suggested to be used as a radiation resistance material. This could be used as radiation protector for tools in high level radiation areas. Samples EPDM/BR conductive blends loaded with 50 phr of CB 70/30 and 50/50 are suggested to be used as a - radiation sensor.
Keywords: Rubbers, Blends, High diene rubbers, polybutadiene (BR), Low-unsaturated rubbers, Ethylene propylene diene monomer (EPDM) rubber, Carbon black (HAF-N330), dc-Electrical conductivity, Dielectric properties, Stress-strain measurements, Hardness test, Pre-extension measurements, Uniaxial extension, -irradiation effects, Space charge limited conduction, Schottky type of conduction, Poole- Frenkel mechanism, Percolation concept, concentration and model, interfacial polarization, Effective Medium Theory, Quemada’s eqn., Guth model, Tensile strength, Elongation at break, Static cyclic strain, Electrical resistivity, Baughmaan and Schakelette derivations, Irradiation resistance dose, sensitive to radiation.