Influence of propene pressure on the isotacticity of polypropene produced with typical C1-symmetric metallocene and Ziegler-Natta catalysts

✍ Scribed by Martin Julius Schneider; Eiichi Kaji; Toshiya Uozumi; Kazuo Soga

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 311 KB
• Volume: 198
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1997.021980919

✦ Synopsis

Abstract

Polymerization of propene was conducted at 40°C under reduced pressure (0.35 – 1.0 atm) using the C~1~‐Symmetric threo‐^i^Pr(3‐^t^BuCp)(3‐^t^BuInd)ZrCl~2~/MAO and TiCl~4~/MgCl~2~/Al(^i^Bu)~3~ catalyst systems and the effect of propene pressure on the microstructure of the resulting isotactic polypropene was investigated. In the case of C~1~‐symmetric metallocene, the [mmmm]‐pentad fraction decreased moderately with decreasing propene pressure, but the magnitude of decrease was much smaller than those reported by Busico et al. using typical C~2~‐symmetric metallocenes. Whereas, the [mmmm]‐pentad fraction of isotactic polypropene obtained with the conventional Ziegler‐Natta catalyst did not change so much in the pressure range. Thus, epimerization of the growing polymer chain was found to be drastically dependent upon the catalyst system.