Mechanical and physical properties of nanosilica/nitrile butadiene rubber composites cured by gamma irradiation

Nitrile Butadiene Rubber (NBR) nanocomposites are prepared with different contents ranging from 5 to 20 phr (part per hundred parts of rubber) of Sinai sand nanoparticles and fumed silica micro particles (SiO2) and mixed with other additives to improve its properties. The nanocomposites were irradiated with gamma irradiation from 25 to 150 kGy. The effect of the silica content and irradiation dose on the morphology, the mechanical and the physical properties of nanocomposites was investigated. The scanning electron microscope (SEM) showed that there is a fine dispersion of nanoparticles into NBR matrix, also some aggregates were observed and their size depends on the SiO2 content. The results indicated that there was an improvement in tensile strength by increasing irradiation doses up to 50 kGy and by increasing silica loading up to 15 phr. Enhancement of volume fraction by increasing irradiation doses and also by increasing silica loading was observed. The thermal gravimetric analysis (TGA) indicated that the thermal stability of NBR increases by increasing silica contents and the increase in irradiated samples is higher than that in un-irradiated. Finally, it is found that the presence of silica in the nanocomposites enhances the electrical insulating properties of the NBR.