Silica-supported metallocenes: effect of the preparation procedure on the morphology of polyethylene particles

Polyethylene (PE) particles are produced by a catalyst prepared by contacti ng a (C4H9Cp)(2)-ZrCl2/MAO pre-mixing solution with SiO2 support. These par ticles have a large granular size and very few fine particles compared with those derived from a catalyst prepared by adsorption of (C4H9Cp)(2)ZrCl2 o nto methylaluminoxane modified SiO2. The amount of Al in the pre-mixing cat alyst has an important effect on its activity and the PE particle size dist ribution. The optimal concentration is about 30 wt.-%. The PE particles pro duced using a pre-mixing catalyst consist of globules with randomly oriente d fiber structure on the surface, whereas those produced using adsorption c atalysts have worm-like fibrils protruding from the PE globule surface.