Some relationships between low temperature properties of lubricating base oils

摘要

Low temperature pumpability is an important property of lubricating oils. The scanning Brookfield technique has been used to study the critical degree of gelation of lubricants at low temperatures (1). Also suggested was a new method to judge the low temperature behavior of lubricants, using gelation index (GI) and gelation temperature (GT) as norms to judge if an oil may cause an air-binding pumping failure. Selby suggested that gelation index values of 16 or greater could indicate the possibility of air binding pumping failures. Gelation temperatures as standards vary with the SAE grade of lubricants (2). Some controversy exists on whether the gelation index relates to air binding tendencies of engine oils (3)-(5), and GI relates to the yield stress of engine oils for many reference oils tested (2), (4). A substantial body of information has been published on low temperature properties of lubricating oils (6)-(9), however, there have been few reports of the relationships of base oils. Correlation of low temperature properties to physical and/or chemical properties of the oil can reduce the number of tests needed and guide the refining process of lubricating base oils. This paper reports the relations of GI, GT, BPT (Borderline Pumping Temperature) with pour point, mean molecular weight and the degree of branching of lubricant base oils.