Study of the structure–activity relationship of metallocene-catalysed poly-α-olefin (mPAO) base oil

Abstract

In this paper, α-olefins with different chain lengths are used as monomers, and metallocene catalysts were used to prepare low-viscosity metallocene-catalysed poly-α-olefin (mPAO) lubricating base oils. Structure and performance tests were carried out. Three molecular structure parameters were selected: relative molecular weight (M_n), branch carbon number (L), and number of branches (n). By mixing and compounding each component oligomer and performing data analysis, the relationships between the molecular structure of mPAO and the key physical properties of the base oil, such as viscosity, viscosity index and pour point (PP), were studied. The results show that in a certain range of M_n, when L (or n) is constant, with an increase in M_n, the viscosity (Kv) and M_n show a power function growth trend, and the growth rate of Kv^40°C is greater than that of Kv^100°C. The viscosity index (VI) increases with increasing M_n, a greater n results in a more obvious growth trend, and a greater L results in a weaker growth trend. When L is constant, an increase in n results in an initial decrease followed by an increase in PP, and PP is the lowest at n = 2.