Polyethylene waxes by metallocenes

Abstract

Abstract The syntheses of low‐molecular‐weight polyethylene (PE), in the presence of catalysts based on five different metallocene frameworks, have been compared. High yields and low molecular masses, typical of industrially relevant PE waxes, can be easily achieved by using overpressure of hydrogen. Particularly suitable for the production of PE waxes are catalytic systems based on the C 2 symmetric rac‐dimethyl‐silyl‐bis‐(2‐methyl‐4‐phenyl‐1‐indenyl)‐zirconium dichloride ( 1 ) and the C 2v symmetric bis ‐ cyclopentadienyl‐zirconium dichloride ( 5 ). The wax yields can be substantially increased by increasing the MAO/Zr molar ratio. The control of the PE molecular weight allows an easy control of physical properties. In fact, as M n increases in the range 10 3 –10 4 g/mol, the degree of crystallinity decreases from nearly 85 to 60% while the melting temperature increases from 125°C up to 135°C. Copyright © 2010 John Wiley & Sons, Ltd.