Preparation and performance evaluation of an ester-bridged antioxidant used as multifunctional additive in ester oil

This study aims to investigate a novel high-efficient antioxidant for synthetic ester oils. An ester-bridged antioxidant, phloroglucinol tris (3-[3,5-di-tert-butyl-4-hydroxyphenyl]) propionate (PTP), was successfully synthesised in high yield under relatively mild reaction conditions. Thermal stability and oxidation resistance of diisooctyl adipate (DOA) ester oil were determined and compared to the typical commercial phenol antioxidants, including its tribological properties. The results indicate that the prepared PTP antioxidant exhibits considerably higher thermal stability than commercial antioxidants, and it also improves the oxidation resistance of the synthetic ester oil more effectively. Moreover, the addition of PTP antioxidant enhanced the wear protection of DOA ester oil without deteriorating its lubricating performance. The ester-bridged antioxidant can be used as a multifunctional additive, which not only exerts excellent thermal stability and oxidation resistance, but can also act as an efficient anti-wear agent in synthetic ester oils.