矿物基础油中不同烃类分子对其物理性质的影响

本文以不同类型且有一定粘度跨度的8类矿物基础油为研究对象，并选取了3种PAO合成油及烷基萘作为纯组分的对比例，系统考察了基础油中各烃类对密度、粘度、粘度指数等几项物理性质的影响，并尝试从理论的角度进行了分析。结果表明：随链烷烃的增加，密度、折射率、分子量均线性下降，粘度则呈指数降低；环烷烃对各项性质的影响不明显，但多环烷烃与分子量线性正相关，而与粘度则是指数正相关；芳烃的影响与链烷烃正好相反；碳数相近时，低芳烃基础油的粘度指数正比于链烷烃含量，但高芳烃基础油则随2环及以上多环芳烃的增加而急剧线性下降，这也正是环烷基油粘温性能极差的根本原因。

Influence of Different Hydrocarbon Molecules on Physical Properties of Mineral Base Oils

Different kinds of base oils with different viscosity were analyzed in this paper, including eight mineral base oils, alkylnaphthalene and three synthetic PAO oils. The influence of different hydrocarbon molecules on physical properties of mineral base oils was investigated, such as density(d), kinematic viscosity(KV), viscosity index(VI), etc. Possible reasons for some inconsistent phenomena in data processing were also theoretically analyzed in detail. The refractive indexes(RI), d and molecular weight(M) decrease linearly with the increase of paraffinic content other than KV, which declines exponentially. There are no clear relationships between physical properties of base oils and naphthenic content while polycyclic alkanes show a strong correlation with M and KV. The influence of aromatics on physical properties of base oils is just the opposite of paraffin's. VI of the base oils with low aromatics content increases linearly as their paraffinic contents rise when their carbon numbers are approximately equal. However, base oils with high aromatics content follow an utterly different rule, in which VI declines dramatically linearly with the increase in polycyclic aromatic content, which is the essential reason why naphthenic base oils all have terrible viscosity-temperature characteristics while paraffinic base oils usually do not.