Impact of the method of Mg 2+ cation introducing into the titanium post-metallocene catalytic system on their activity

Abstract

Abstract This work shows for the first time the influence of the method of introducing Mg compounds into a post-metallocene-type catalytic system on its catalytical performance and the properties of the resulting polymer, and it is concluded that the real catalytic center is heterometallic Ti/Mg complexes. Compares three different approaches to introducing Mg compounds into catalytic systems containing a titanium(IV) dichloride complex with an (O^O)2- type ligand and an organoaluminium compound - the use of Al/Mg co-catalysts, the immobilization of a Ti complex on the surface of anhydrous MgCl2 and in situ preparation of heterometallic Ti/Mg complexes. All three approaches lead to the production of ultra-high molecular weight polyethylene, but systems with externally introduced magnesium chloride showed the lowest productivity. UHMWPE samples synthesized on Ti/Mg precatalysts and conventional OAC are suitable for solvent-free solid-phase processing into high-strength, high-modulus film threads.