Choice of antioxidants and their synergistic effect study towards new insulation oil

In order to improve the oxidation stability of a new insulation oil derived from mineral oil and natural ester, the composite antioxidant used in the oil which were 2,6-ditert-butyl-4-methylphenol (T501) and high-purity alkylation-alpha-naphthylamine (L06) have been selected by using high pressure differential scanning calorimetry (PDSC), and the best concentration of the composite antioxidant in the oil was determined: 0.3%T501 + 0.3% L06. PDSC test results show that the composite antioxidant can enhance the new insulation oil oxidation stability significantly, making the new insulation oil exhibit more remarkable anti-oxidative activity than mineral oil. T501 and L06 can not react with each other and this was proved by molecular modeling and FT-IR spectroscopy. PDSC and FT-IR spectroscopy test results indicate that it is the synergistic antioxidant effect of composite antioxidant improving the new insulation oil oxidation stability. The synergistic antioxidant mechanism of the composite antioxidant was analyzed at last.