Abstract: Poly-alpha-olefin (PAO) is a kind of high-quality based oil of synthetic lubricants. Its relative molecular mass and distribution directly affect macroscopic properties. A method was developed for characterizing the relative molecular mass and distribution of 1-decene oligomer. Gel permeation chromatograph (GPC) equipped with differential refractive index (RI) was used to characterize the relative molecular mass and distribution of PAO. The operation conditions of GPC-RI were optimized, including the flow rate of the mobile phase and the combination of gel chromatographic columns to optimize the separation effect and operability. The operation mode was that the tetrahydrofuran as flow phase with a flow rate of 0.8 mL/min, combination of three columns of Styragel HR0.5, Styragel HR1, and PLGEL 3μm MIXED-E in series to separate PAO. The chromatographic efflux curve was processed by universal calibration method with polystyrene (PS) as the standard sample. Compared with GPC-LLs, the relative deviation for weight average relative molecular mass measures was less than 3%.

Key words: poly-alpha-olefin, relative molecular mass, GPC-RI, universal calibration