三羟甲基丙烷复合酯热氧化规律及氧化动力学研究

对三羟甲基丙烷复合酯分别进行不同温度与时间下的恒温氧化,检测其氧化后的黏度、黏度指数和酸值,并通过函数拟合得出它们随氧化温度与时间的变化规律;使用PDSC测试被氧化样品的起始氧化温度,并计算活化能、氧化速率常数和氧化半衰期,得到氧化温度与时间对油品后续氧化安定性的影响规律。结果表明:油品黏度与酸值的变化规律均近似logistic函数曲线,即起初增长缓慢,随后迅速增长并达到最快速率,最终速率逐渐下降;黏度与酸值函数的拟合参数与氧化温度密切相关,可用于评价与预测油品的氧化行为;三羟甲基丙烷复合酯经历不同条件的高温氧化后始终具有较高的黏度指数,并且起始氧化温度和活化能均未发生显著变化,表明其氧化后仍有着优异的黏温性能和氧化安定性。

Researches on Thermal Oxidation and Oxidation Kinetics of Trimethylolpropane Complex Ester

The trimethylolpropane complex esters were oxidized by the oven at different temperatures and time.The kinematic viscosities,viscosity indexes and acid values of oxidized esters were tested respectively,and their change rules with oxidation temperature and time were obtained by fitting function.By testing the initial oxidation temperatures of the oxidized samples with the pressurized differential scanning calorimetry,calculating the activation energy,oxidation rate constant and half life period,the effects of oxidation temperature and time on the oxidation stability of the oxidized samples were investigated.The results show that the variation trends of kinematic viscosity and acid value are close to logistic function curve,that is,they increase slowly at the initial stage,then grow rapidly and reach the fastest rate,and finally the rate is gradually decreased.The fitting parameters of viscosity and acidity function are closely related to oxidation temperature,which can be used to evaluate and predict the oxidation behaviors of oxidized esters.The trimethylolpropane complex esters keep high viscosity index after high temperature oxidation under different conditions,and their initial oxidation temperature and activation energy have not changed significantly,indicating that the trimethylolpropane complex esters still have excellent viscosity temperature properties and oxidation stability after oxidation.