润滑油基础油结构的核磁共振表征

以6种费-托合成润滑油基础油和14种加氢异构润滑油基础油为研究对象，采用核磁共振技术对其分子结构及组成进行分析，并计算其分子结构参数，将20种基础油的黏度指数与识别出的8种分子结构进行关联，考察组成对黏度指数的影响。研究结果表明，润滑油基础油分子中2位、3位、4位甲基取代结构的存在会降低其黏度指数，而正构烷烃和6位或7位取代结构分子则有利于提高其黏度指数。对于费-托合成润滑油基础油，当分子平均碳数相近时，支化度和支化点数越大，润滑油基础油结构的分支程度越高；当分子平均碳数不同时，相对支化点数越大，润滑油基础油结构的分支程度越高；黏度指数随着相对支化点数的增加呈线性增长，相关系数为0.95。

NMR CHARACTERIZATION OF LUBE BASE OIL STRUCTURE

The structures and properties of six lube base oils produced by Fischer-Tropsch synthesis and fourteen hydroisomeric lube base oils were studied and analyzed by nuclear magnetic resonance(NMR) technology. The correlations of viscosity index(VI) and contents of 8 kinds of isomers were established. The influences of hydrocarbon composition and structure of lube base oils on their VI were investigated. The specific structures played an important role in controlling the viscosity-temperature performance of lube base oils. The presence of the molecules with methyl-substituted at position 2, 3 and 4 in lube base oils reduced the VI of lube base oils, while normal paraffins and the methyl substituted at position 6 or 7 structures contribute positively to the VI. For lube base oils produced by Fischer-Tropsch synthesis, the larger the branched degree and branched number of lube base oils were, the higher the branching degree of lube base oils were. For lube base oils with different average carbon numbers of molecules, the branching degree decreased with the reduction of relative branched number. VI corresponded linearly to the relative branched number with correlation coefficient of 0.95.