Modification of a Ziegler-Natta catalyst with a metallocene catalyst and its olefin polymerization behavior.: An article from: Polymer Engineering and Science

This digital document is an article from Polymer Engineering and Science, published by Society of Plastics Engineers, Inc. on July 1, 1999. The length of the article is 4232 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

From the author: A Ziegler-Natta catalyst was modified with a metallocene catalyst and its polymerization behavior was examined. In the modification of the Ti[Cl.sub.4] catalyst supported on Mg[Cl.sub.2] (Mg[Cl.sub.2]-Ti) with a rac-ethylenebis(indenyl)zirconium dichloride (rac-Et[(Ind).sub.2]Zr[Cl.sub.2]. EIZ) catalyst, the obtained catalyst showed relatively low activity but produced high isotactic polypropylene. These results suggest that the EIZ catalyst might block a non-isospecific site and modify a Ti-active site to form highly isospecific sites. To combine two catalysts in olefin polymerization by catalyst transitioning methods, the sequential addition of catalysts and a co-catalyst was tried. It was found that an alkylaluminum like triethylaluminum (TEA) can act as a deactivation agent for a metallocene catalyst. In ethylene polymerization, catalyst transitioning was accomplished with the sequential addition of bis(cyclopentadienyl)zirconium dichloride ([Cp.sub.2]Zr[Cl.sub.2])/methylaluminoxane (MAO), TEA, and a titanium tetrachloride/vanadium oxytrichloride (Ti[Cl.sub.4]/VO[Cl.sub.3], Ti-V) catalyst. Using this method, it was possible to control the molecular weight distribution (MWD) of polyethylene in a bimodal pattern. In the presence of hydrogen, polyethylene with a very broad MWD was obtained due to a different hydrogen effect on the [Cp.sub.2]Zr[Cl.sub.2] and Ti-V catalyst. The obtained polyethylene with a broader MWD exhibited more apparent shear thinning.

Citation Details
Title: Modification of a Ziegler-Natta catalyst with a metallocene catalyst and its olefin polymerization behavior.
Author: Tae Oan Ahn
Publication:Polymer Engineering and Science (Refereed)
Date: July 1, 1999
Publisher: Society of Plastics Engineers, Inc.
Volume: 39 Issue: 7 Page: 1257(8)

Distributed by Thomson Gale