Efficient Synthesis and Drag Reduction Properties of Ultra-high Molecular Weight Poly-α-olefin

Using 1-octene and 1-decene as monomers, and a catalytic system of TiCl4 (a fourth-generation Ziegler-Natta catalyst) loaded on MgCl2 as the main catalyst, triethylaluminium (Et3Al) as a co-catalyst, and methylcyclohexyldimethoxysilane (CHMDMS) as the external electron donor, under both magnetic stirring and mechanical stirring conditions, respectively, a series of poly-a-olefin (PAO)-based drag reducer were successfully prepared. As proven by high-temperature gel permeation chromatography, the newly obtained polymers not only had very high molecular weight, (weight average molecular weight of most of the polymers was higher than 3x10(6)), but also had very narrow molecular weight distribution (polymer dispersity index was lower than 3.0 for most of the polymers), suggesting a uniform distribution of all polymer chains. The obtained polymers were characterized by C-13-nuclear magnetic resonance (C-13-NMR), differential scanning calorimetry (DSC), thermal gravimetric analyzer (TGA) and X-ray diffraction (XRD), respectively. It turned out that target polymers with expected composition were obtained. Most of the polymers were amorphous, making them well-soluble in oils. All polymers showed high decomposition temperature beyond 300 degrees C, much higher than working temperature of drag reducers. The loop pipeline cycling experiment indicated that the drag reduction efficiency of the newly obtained polymers was greatly improved compared with those of commercial products and previous reports.