Effect of nano-TiO2 immobilized antioxidant on ageing resistance behavior of thermoplastic vulcanizate exposed to UV/O3

Nano-TiO2 immobilized antioxidant (TiO2-KH550-AG) was prepared to improve the ageing resistance of thermoplastic vulcanizate (TPV) exposed to UV/O3. TiO2 nanoparticles were firstly modified with 3-aminopropyltriethoxysilane (KH550) and then reacted with the antioxidant, 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid (AG), through the acyl chloride reaction followed by the amidation. FT-IR, XPS and TGA measurements confirmed that the antioxidant (AG) was chemically immobilized onto the nano-TiO2 surfaces. TPV/TiO2-KH550-AG nanocomposites were prepared by melt mixing. SEM observation showed that TiO2-KH550-AG was homogeneously dispersed into the matrix of TPV. The UV/O3 ageing test of the samples was carried out in the environment with constant UV intensity of 1.40 mW/cm2 and ozone concentration of 100 ± 4 mg/m3. The ageing resistance behavior of the TPV/TiO2-KH550-AG nanocomposites was evaluated by the changes of surface morphology, mechanical properties and carbonyl index during the UV/O3 ageing test. It was observed that the TPV/TiO2-KH550-AG exhibited high stability during the process of UV/O3 ageing. The results revealed that the anti-ageing efficiency of TiO2-KH550-AG was superior to the mixture of the corresponding AG and modified TiO2, owing to the better dispersion and migration resistance of TiO2-KH550-AG.