Abstract: A process is provided for extruding a bimodal polyethylene resin. The process includes providing a polyethylene homopolymer or copolymer resin having a bimodal molecular weight distribution; conveying the resin through an extruder having a feed zone in which the resin is not melted, a melt-mixing zone in which at least a portion of the resin is melted, and a melt zone in which the resin is in a molten state, each zone being partially filled with the resin; and contacting the molten resin in the melt zone with a gas mixture of 8 to 40% by volume O2. The resin can be further pelletized. The oxygen-tailored resin can be used to make polyethylene films having improved bubble stability.

Abstract: A process is described for forming a catalyst precursor, for copolymerizing ethylene and an alpha-olefin of 3 to 10 carbon atoms, by preparing a contact mixture of an inert solvent, dibutylmagnesium and tetraalkyl orthosilicate which is free of precipitate and adding silica to the contact mixture to form a slurry to form a supported catalyst precursor. Titanium tetrachloride is then incorporated into the support in a specific ratio to the magnesium and silane components. Activation of this catalyst precursor with a trialkylaluminum compound results in a catalyst system which is effective for the production of ethylene copolymers.