酯类油TMPTO的热氧化规律及抗氧化性能改进研究

发布时间：2018-05-09 04:26

  本文选题：三羟甲基丙烷油酸酯 + 氧化　； 参考：《机械科学研究总院》2015年硕士论文

【摘要】：本文以国家“973”课题“润滑添加剂的减摩抗氧化特性及其对合成润滑油使役行为的作用规律”为依托,系统测试表征了酯类基础油三羟甲基丙烷油酸酯(缩写TMPTO)、偏苯三酸三异癸酯(缩写TDTM)和己二酸二异辛酯(缩写DEHA)的理化性能、热氧化性能和摩擦学性能;运用红外光谱和激光拉曼光谱方法深入研究了温度、氧气以及金属催化对TMPTO化学结构的作用,探讨了TMPTO分子结构变化与其理化性能、热氧化性能退化的关联规律;在从分子尺度揭示TMPTO基础油热氧化失效机制的基础上,导入功能抗氧剂来阻断体系中TMPTO化学结构的氧化,提出了延长TMPTO基础油高温使用寿命的建议。论文的主要成果及结论如下:在热氧化过程中,TDTM基础油的氧化安定性好,其运动粘度、总酸值和粘度指数都表现出较好的稳定性;DEHA基础油的总酸值增长最显著;TMPTO基础油的运动粘度增长较快,随着氧化时间的延长,TMPTO基础油的运动粘度呈现指数关系增大,其总酸值呈现线性关系增大;随着氧化时间的延长,TMPTO和DEHA基础油的粘度指数呈现降低趋势;TMPTO基础油的摩擦学性能优于DEHA基础油和TDTM基础油。首次通过TMPTO基础油原位热氧化的拉曼光谱分析发现,随着氧化温度的升高,TMPTO基础油的主要结构组成(=C-H、C=C以及-CH2-)的拉曼峰强降低,C=C伸缩振动峰的拉曼位移线性增大;冷却至室温后,=C-H和C=C的拉曼峰强可部分恢复,-CH2-则完全恢复,C=C伸缩振动峰的频移完全消失。随着热氧化时间延长,TMPTO分子结构中=C-H可完全消耗,C=C可部分消耗;C=C的化学变化过程遵循一级反应动力学,其反应速率常数受单位体积油品的溶氧量影响显著。金属催化实验表明,Fe的催化作用明显加剧TMPTO基础油理化性能和热氧化性能的恶化,Cu其次,Al最小;与玻璃容器相比,Fe的催化作用会明显增大TMPTO碳碳双键的一级反应速率常数。在95℃和135℃氧化条件下,适量的抗氧剂L115和T558能够较好地抑制TMPTO基础油运动粘度和总酸值的增长;在175℃和250℃氧化条件下,胺类抗氧剂T558以及胺类T557、T558与酚类T502的复配抗氧剂能够较好的抑制TMPTO基础油运动粘度和总酸值的增长。研究发现,氧化稳定性评价方法(高压差示扫描量热法PDSC、旋转氧弹法RBOT)的测试原理差异,对抗氧剂改进TMPTO基础油抗氧化性能的表征有很大影响,可导致相同试验温度下截然相反的氧化诱导时间数据。在PDSC试验中,胺类抗氧剂的改进作用优于酚类抗氧剂,在RBOT试验中,酚类抗氧剂的改进作用优于胺类抗氧剂。
[Abstract]:This paper is based on the national "973" project, "antifriction and antioxidation characteristics of lubricating additives and their effects on the behavior of synthetic lubricating oils". The physical and chemical properties, thermal oxidation and tribological properties of ester base oil trimethylol propane oleate (TMPTOA), triisodecyl trimethylate (TDTM) and diisooctyl adipate (DEHAA) were investigated. The effects of temperature, oxygen and metal catalysis on the chemical structure of TMPTO were studied by means of infrared spectroscopy and laser Raman spectroscopy. The relationship between the molecular structure of TMPTO and its physical and chemical properties and thermal oxidation degradation was discussed. On the basis of revealing the failure mechanism of thermal oxidation of TMPTO base oil on molecular scale, functional antioxidants were introduced to block the oxidation of TMPTO chemical structure in the system, and some suggestions for prolonging the high temperature service life of TMPTO base oil were put forward. The main results and conclusions are as follows: in the process of thermal oxidation, TDTM base oil has good oxidation stability and kinematic viscosity. The total acid value and viscosity index showed good stability. The increase of total acid value of DEHA base oil was the most significant. The kinematic viscosity of TMPTO base oil increased rapidly, and the kinematic viscosity of TMPTO base oil increased with the extension of oxidation time. With the increase of oxidation time, the viscosity index of TMPTO and DEHA base oil decreased. The tribological properties of TMPTO base oil were better than that of DEHA base oil and TDTM base oil. Raman spectroscopy analysis of in-situ thermal oxidation of TMPTO base oil shows for the first time that the Raman peak intensity decreases linearly with the increase of oxidation temperature, and the Raman shift increases linearly with the increase of oxidation temperature. After cooling to room temperature, the Raman peaks of C H and C C can be partially recovered and the frequency shift of the stretching vibration peaks of C C can be completely recovered. With the prolongation of the thermal oxidation time, the chemical change process of TMPTO molecular structure in which the C ~ (- H) can completely consume C ~ (2 +) can partially consume C ~ (2 +) C follows the first-order reaction kinetics, and its reaction rate constant is significantly affected by the dissolved oxygen content of the unit volume of oil. The results of metal catalytic experiments showed that the degradation of physical and chemical properties and thermal oxidation properties of TMPTO base oils was obviously aggravated by the catalytic action of Fe, and the first order reaction rate constant of TMPTO carbon / carbon double bonds was increased obviously compared with that of glass containers. Under the oxidation conditions of 95 鈩，

本文编号：1864586