Effect of Coated Rutile TiO2 and Disazopyrazolone Dye Additives on Unvulcanized Styrene Butadiene Rubber During Photo-Ageing

Abstract

The effect of coated rutile titanium dioxide (TiO2) and a disazopyrazolone dye (azo dye) on the mechanism and the kinetic of photo-oxidation of unvulcanized styrene butadiene rubber (SBR) composites under accelerated UV-visible irradiation (λ > 290 nm at 35 °C) has been investigated using several techniques such as infrared spectroscopy, UV-visible spectrophotometry, and gel fraction measurements. Different photo-products resulting from the photo-ageing such as alcohol, ketone, or acids as well as cross-linked network were identified. The incorporation of TiO2 rutile and an azo dye into the matrix did not modify the mechanism of photo-oxidation. However, they have a significant effect on the kinetic of photoproducts accumulation. Both fillers protect the matrix from photo-oxidation. TiO2 rutile, thanks to its inorganic coating at the surface, dissipates part of the UV-visible radiation received by the polymer. The activity mechanism of azo dye consisting of a combination of its function as an antioxidant and light absorber, presents a better stabilizing effect compared with TiO2 rutile.