Gamma irradiation effects on styrene butadiene rubber/Pb3O4: Mechanical, thermal, electrical investigations and shielding parameter measurements

Polymer composites of Styrene-Butadiene Rubber SBR filled with Pb3O4 have been prepared with different concentrations ranging between (4.5-37.8 wt%). The linear mu and mass attenuation coefficients mu(m) of all samples have been investigated at energies 1173, 1333 and 662 KeV from 60Co and 137Cs point sources, and results were compared with the calculated one via WinXcom at the same photon energies, it was clear that mu m increases in proportion to the concentration of filler. The radiation protection efficiency RPE% increased with increasing filler concentration while HVL (half-value layer) and TVL (tenth value layer) were decreased with increasing filler concentration; also, atomic effective number Z(eff) has computed. Activation energy of decomposition was calculated for samples that ranged from (190.71-225.74 J/K.mol), and kinetic parameters for thermal degradation of the SBR/Pb3O4 have been tabulated. The samples were irradiated with doses (50,100,150 and 200 kGy), mechanical properties have been carried out such as tensile strength, hardness (shore A) and elastic modulus, all showed improvement with irradiation doses up to 100 kGy except elongation at break decreased with increasing filler content. Electrical properties have been measured for the samples at room temperature to identify the conduction mechanism, which showed the applicability of Schottky-Richardson mechanism. The hopping distance of the charge carrier has been determined theoretically, ranging between (3 x 10(-8)-1.43 x 10(-8) m). Also, the dispersion and morphological analysis of composites have been studied using the Scanning Electron Microscope. The composites showed good performance as light-shielding material for low energies up to 300 KeV, where RPE% increased by increasing Pb3O4 concentrations from 8% (SBR1) to reach 46% (SBR5) at 662 KeV; similarly, the HVL decreased by 64% from (SBR1) to (SBR5).