Effects of octamethylcyclotetrasiloxane grafting and in situ silica particle generation on the curing and mechanical properties of a styrene butadiene rubber composite

The reinforcement of octamethylcyclotetrasiloxane (D(4)) grafted styrene butadiene rubber (SBR-g-D(4)) with in situ generated silica was performed using the sol–gel reaction of tetraethoxysilane (TEOS) in latex. The characterization of SBR-g-D(4) and in situ generated silica reinforced SBR-g-D(4) was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The grafting efficiency of the styrene butadiene rubber (SBR) was determined by a gravimetric method. It was found that the constant silicon content and the grafting efficiency of SBR were 1.72% and 0.13 wt% when the weight ratio of D(4) to SBR was 0.20. The effects of the D(4) and in situ generated silica content on the curing characteristics, mechanical properties and morphology of SBR latex were investigated. The mechanical properties of in situ generated silica reinforced SBR-g-D(4) vulcanizates were improved significantly compared to raw SBR vulcanizate when the in situ generated silica content was 18.05%. Compared with silica reinforced SBR-g-D(4), the tensile strength, wet skid resistance and rolling resistance of the in situ generated silica reinforced SBR-g-D(4) were better. This is because of the higher crosslinking degree in the SBR-g-D(4) matrix and the strong chemical bond between SBR-g-D(4) molecular chains and in situ generated silica. Scanning electron microscopy analysis revealed good silica filler dispersion in all the reinforced SBR-g-D(4) vulcanizates.