黏度指数改进剂对基础油性能的影响

Effects of Viscosity Index Improvers on the Performances of Base Oils

用凝胶色谱测定乙丙共聚物(OCP)和氢化苯乙烯异戊二烯(SDC)黏度指数改进剂的分子量和分散度,用运动黏度测定法、高温高剪切表观黏度测定法测定OCP和SDC在4类基础油中的运动黏度和高温高剪切表观黏度,用柴油喷嘴测定法测定其100℃下的剪切稳定性,用冷启动模拟机法测定其-15℃与-20℃的低温动力黏度。结果表明:SDC分子量小于OCP,但分散度大于OCP,在相同基础油中其黏温性能、剪切稳定性优于OCP类;在4类基础油中,OCP和SDC的黏温特性表现为Ⅳ类>Ⅲ类>Ⅰ类,稠化特性表现为Ⅳ类>Ⅰ类>Ⅲ类>Ⅱ类,剪切稳定性表现为Ⅳ类>Ⅲ类>Ⅱ类>Ⅰ类;OCP和SDC稠化油的-15℃以及-20℃的低温动力黏度与基础油相当。

Molecular weight and polymer dispersion of Olefin Copolymers （OCP ）and Styrene-butadiene Copolymers （SDC）type viscosity index improver were measured by Gel Chromatography.The kinematic viscosity and apparent viscos-ity of OCP and SDC in four groups of base oils were measured by the method of determination of kinematic viscosity and apparent viscosity at high temperature and high shear rate.A European diesel injector apparatus was used to measure the shear stability at 100 ℃,and the cold cranking simulator were used to measure the low temperature dynamic viscosity of -15 ℃and -20 ℃.The results indicate that SDC has smaller molecular weight and larger dispersion than OCP,and the viscosity-temperature characteristics and shear stability of SDC are better than that of OCP in the same base oils.In four groups of base oils,the viscosity-temperature characteristics of OCP and SDC are showed GroupⅣ 〉GroupⅢ 〉GroupⅠ,the thickened characteristics are indicated Group Ⅳ〉Group Ⅰ〉Group Ⅲ〉Group Ⅱ,the shear stability is stated GroupⅣ 〉GroupⅢ〉GroupⅡ〉GroupⅠ.The dynamic viscosity of OCP and SDC thickened oil at low temperature of -15 ℃and 20 ℃ is equal to the corresponding base oils.