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Effects of Electron Donors on Active Sites Distribution of MgCl 2 ‐Supported Ziegler‐Natta Catalysts Investigated by Multiple Active Sites Model
Author(s) -
Wang Qi,
Murayama Namiko,
Liu Boping,
Terano Minoru
Publication year - 2005
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200400502
Subject(s) - active site , ziegler–natta catalyst , natta , polymerization , steric effects , chemistry , catalysis , electron donor , polymer chemistry , stereochemistry , organic chemistry , polymer
Summary: The stopped‐flow polymerization of propylene catalyzed by a Ziegler‐Natta catalyst in the presence of internal and external electron donors was carried out. The influence of the electron donors on the active sites of the catalyst was investigated using a multiple active site model. The variation of each group of active sites, such as the concentration and k p of each site at various polymerization times, can be obtained from this model. It was found that an electron donor mainly affects the aspecific active site by reducing its concentration and increasing its k p . The isospecific site is only slightly altered in terms of concentration and its k p because of steric hindrance.Variation of [ C *] of each active site of TiCl 4 /MgCl 2 ‐AlEt 3 at various polymerization times.