The thermal stability and high temperature oxidation resistance of hindered phenols with different structures in lube base oils were investigated by thermogravimetric analysis(TGA)and high-pressure differential scanning calorimetry(PDSC),respectively.The antioxidation characteristic parameters of hindered phenols were calculated by ab initio algorithm of quantum chemistry,and the quantitative relationship between molecular structure parameters of hinderedg phenols and high temperature oxidation induction period was established by genetic algorithm.The results show that the relative molecular weight is the key factor affecting the thermal stability of hindered phenols.The established quantitative structure-property relationship equation has clear physical and chemical significance,and the cross-test correlation coefficient RCV2 is 0.914,which has good prediction ability.Bond dissociation energy(BDE)of O—H,mulliken charges of S atoms(Qs),and energy of molecular maximum occupied orbital(EHOMO)are the three key molecular characteristic parameters affecting the high-temperature antioxidant performance of hindered phenols.The order in which these three parameters influence the high-temperature antioxidant performance of hindered phenols is as follows:QS＞BDE(O—H)＞EHOMO.In order to improve the antioxidant activity,sulfur-containing hindered phenols should be designed and developed with the following structural characteristics:more negative Mulliken charges of S atoms,lower dissociation energy of O—H bonds and higher energy of molecular maximum occupied orbital.This indicates the direction for the design and development of high performance phenolic antioxidant products with new structure.
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