Dow Global Technolgoies LLC

W.r. Grace & Co. -conn.

Michael W Tilston

Linfeng Chen

Robert Reib

Mehmet Demirors

Teresa Plumley Karjala

Mridula Babli Kapur

Richard E Campbell, Jr

Sean W Ewart

David M Pearson

Jan Willem Van Egmond

Stephanie M Whited

Ping P Cai

Roger B Painter

Robert N Reib

Richard E Campbell

A zirconocene-titanocene catalyst system comprising a zirconocene catalyst and a titanocene catalyst; polyolefins; methods of making and using same; and articles containing same.

Zirconocene-titanocene catalyst system

The invention provides a process to prepare a second propylene-based polymer from a first propylene-based polymer, each propylene-based polymer having a melt flow rate (MFR; 2.16 kg/230&#xb0; C.) with the MFR of the second propylene-based polymer greater than the MFR of the first propylene-based polymer, the process comprising the step of contacting under visbreaking conditions the first propylene-based polymer with at least one carbon-carbon (C&#x2014;C) free-radical initiator of Structure (I): (Structure (I)) wherein R, R, R, R, Rand Rare each, independently, a hydrocarbyl group or a substituted hydrocarbyl group, and wherein, optionally, two or more R groups (R, R, R, R, Rand R) form a ring structure.

Process to visbreak propylene-based polymers with C&#x2014;C initiators

The present invention relates to an improvement for gas phase olefin polymerization process under two or more different flow regimes. The process involves adding a mixed electron donor system to a reactor having two or more different flow regimes, wherein the mixed electron donor system comprises at least one selectivity control agent and at least one activity limiting agent. The invention is particularly well suited for reactor systems which include a regime characterized by having a low-velocity or high-solid holdup, which have been reported to have operational problems such as particle agglomeration and formation of polymer 'chunks'.

Gas-phase polymerization process having multiple flow regimes

A process for the polymerization of olefin monomers comprising contacting ethylene or a mixture of ethylene and one or more C&#x3b1; olefins with a catalyst composition comprising one or more Group 3-10 transition metal containing, Ziegler-Natta, procatalyst compounds; one or more alkylaluminum cocatalyts; and one or more polymerization control agents, said process being characterized in that at least one such polymerization control agent is an alkyl or aryl, ester of an aliphatic or aromatic (poly)carboxylic acid optionally containing one or more substituents comprising a Group 13, 14, 15, or 16 heteroatom.

Catalyst composition for ethylene polymerization

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Missouri City, TX, United States of America

Michael W Tilston