Investigation of thermal and mechanical properties of styrene–butadiene rubber nanocomposites filled with SiO2–polystyrene core–shell nanoparticles

Abstract

The present study investigates the effect of SiO2–polystyrene core–shell nanoparticles on properties of styrene–butadiene rubber nanocomposites. Meanwhile, SiO2–polystyrene core–shell nanoparticles were synthesized under controlled ultrasound assisted microemulsion technique. Further, as-synthesized SiO2–polystyrene nanoparticles were subjected to various characterization techniques, such as X-ray diffraction, field emission scanning electron microscope, transmission electron microscope, and Fourier transform infrared spectroscopy to know its size, shape, and presence of functional groups. The average diameter of SiO2–polystyrene nanoparticles was found to be ∼45 nm. SiO2–polystyrene nanoparticles were reinforced in styrene–butadiene rubber using two-roll mill and molded on compression molding machine, which then subjected to various testings (X-ray diffraction, field emission scanning electron microscope, thermogravimetric analysis, and universal testing machine). Moreover, the crosslinking density was investigated using solvent sorption technique. The properties of styrene–butadiene rubber nanocomposites were found to be improved with increasing amount of SiO2–polystyrene nanoparticles (2.0 wt%) and decreases subsequently (2.5 wt%). This enhancement in properties was due to uniform dispersion of core–shell nanoparticles with embedded chains of rubber. Also this enhancement in properties was due to smooth surface of core–shell nanoparticles (2.0 wt%) and decreases subsequently at higher amount of loading (2.5 wt%). However, the minimal crosslinkage leads to more solvent sorption, which leads to increase in average molecular weight. This decrement in the crosslinkage density with increase in average molecular weight was due to voids or free volume inside the matrix, which allows the solvent to get penetrated inside the matrix. This effect was not due to styrene–butadiene rubber matrix but due to shell of polystyrene over SiO2.