Micro-mechanism study on different antioxidants protective effect of vegetable oil by ReaxFF molecular dynamics

Abstract

The aging problem of vegetable oil has severely restricted the popularization and application of vegetable oil transformers. Adding antioxidants is the most recommended solution. At present, there is insufficient research on the micro-mechanism of the protective effect of antioxidants on vegetable oil. In this paper, multiple vegetable oil models with different types and concentrations of antioxidants were established. Then the molecular dynamics simulation based on ReaxFF was carried out at different temperatures and oxygen content. Results show that the protective mechanism of antioxidants is to release H and combine with free radicals generated by the decomposition of unsaturated fatty acids (UFA) in the oil. In addition, the protective effects of four antioxidants are different. The stronger ones are tert-butyl hydroquinone (TBHQ) and butylated hydroxytoluene (BHT), while the weaker ones are butylated hydroxyanisole (BHA) and propyl gallate (PG). TBHQ has a better protective effect at low concentration, but the decomposition of UFA is promoted at high concentration. When the temperature rises, the decomposition of UFA would be promoted. With the addition of oxygen, small molecular compounds are easily oxidized, and the decomposition of UFA is accelerated. The above research could reveal the microscopic mechanism of antioxidant protection on vegetable oil, providing theoretical reference for further exploration of effective vegetable oil aging protection technology.