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New evidence of the presence of internal electron donors in active sites of heterogeneous Ziegler‐Natta catalysts
Author(s) -
Xu Junting,
Feng Linxian,
Yang Shilin,
Wu Yinan,
Yang Yiqing,
Kong Xiangming
Publication year - 1996
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.1996.030170906
Subject(s) - natta , fractionation , electron donor , catalysis , ziegler–natta catalyst , chemistry , polymer chemistry , electron , fraction (chemistry) , active site , materials science , chemical engineering , organic chemistry , polymer , polymerization , physics , ethylene , quantum mechanics , engineering
Poly(propylene) samples produced by heterogeneous Ziegler‐Natta catalysts containing different internal electron donors were fractionated by using temperature rising elution fractionation; some key fractions were analyzed with 13 C NMR. It was found that internal electron donors with different structures can convert aspecific active sites into different isospectrific ones. The employment of bis(2‐ethylhexyl) phthalate as internal electron donor leads to chemically inverted structures in the atactic fraction. This suggests that an internal electron donor may also exist in the environment of aspecific active sites.