Aging properties of ultraviolet absorber/SBS modified bitumen based on FTIR analysis

•The FTIR was applied to investigate the aging characteristics of the UVA/SMBs.•The three UVAs exhibit an obvious improvement on aging resistance of the LSMB.•The UV326/LSMB exhibits the best resistance to both the thermal-oxidative and UV aging. Three kinds of ultraviolet absorbers (UVAs) and two types of styrene–butadienestyrene (SBS) were used to prepare the UVA/SBS modified bitumen (UVA/SMB) via melt blending. The thermal-oxidative and ultraviolet (UV) aging of the samples were accelerated by the thin film oven test (TFOT) and UV aging test, respectively. The effects of different UVAs on aging properties of the SBS modified bitumen were evaluated via the change of several functional group indexes analyzed by the Fourier transform infrared spectroscopy (FTIR). Then, the dynamic shear rheometer (DSR) test was used to verify the consequences obtained from the FTIR analysis and to establish the relationship between the chemical structure and the macro-performance of the UVA/SMBs. The results show that the effect of the three UVAs on aging properties of the SBS modified bitumen is not only dependent on the type of UVA, but also related to the structure of SBS polymer. The three UVAs exhibit an improvement on both the thermal-oxidative and UV aging resistance of the linear SBS modified bitumen since the addition of these UVAs inhibits the oxidation of bitumen molecules and degradation of SBS polymer during the aging processes. However, some of the UVAs accelerate the variation of functional group indexes during the aging process and thus deteriorate the aging properties of the radial SBS modified bitumen.