Unveiling the Micro-Mechanism of Functional Group Regulation for Enhanced Dielectric Properties in Novel Natural Ester Insulating Oil TME-C.

The functional groups in the molecular structure of natural ester insulating oil have a significant impact on its physicochemical and electrical properties. This article takes the novel synthetic ester TME-C and traditional natural ester GT molecules as research objects, and based on density functional theory (DFT) calculations, systematically explores the micro-mechanism of the effects of C=C double bonds, ester groups (-COOC), and β-H groups on the performance of insulating oils. The results show that the chemical stability and anti-aging ability of the TME-C molecule are significantly improved by eliminating the C=C double bond and β-H group. The electronic behavior of the TME-C molecule is mainly controlled by the ester group (-COOC), while the GT molecule is significantly affected by the unsaturated C=C double bond, resulting in a significant difference in the mode of electronic transition between the two molecules: the TME-C molecule shows the n→σ∗ transition, while the GT molecule is the π→π∗ transition. In addition, the HOMO orbital energy level, electron transition energy, and ionization energy of the GT molecules are lower than those of the TME-C molecules. Under the action of an external electric field, the TME-C molecules exhibit excellent dielectric properties. In summary, the TME-C molecules not only overcome the aging defects of traditional natural ester insulating oils, but also possess excellent insulation properties, making it a new type of insulating oil material with broad application prospects.