Aging behavior and thermal stability of styrene-butadiene-styrene tri-block copolymer (SBS) in blends were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TG). From the analysis of FTIR, the alcohol and carboxyl hydroxyl groups will be gradually generated during the thermal and ultraviolet aging, and the effect of short-term high temperature is more serious than longterm ultraviolet exposure on the structure of SBS; XPS results show that oxygen/carbon ratio of thermal and ultraviolet aged SBS have significantly increased, while the relative concentration of C-O-H(R) is far higher than that of COOH(R); inferred oxidation mechanism of SBS based on the analytical results of FTIR and XPS shows alcohol, carboxyl, ether, ketone, etc. have mainly formed in blends after thermal or ultraviolet aging; moreover, on account of the distribution index of carbon-oxygen binding state of thermal and ultraviolet aged SBS(respectively 3.15 and 1.28), C-O is easily produced than C=O and the effect of thermal aging is more obvious; from the results of TG, the maximum decomposition rate and temperature decrease after aging.

Keywords: styrene-butadiene-styrene tri-block copolymer (SBS); thermal aging; ultraviolet aging; oxidative degradation; blends