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Effect of AlEt 3 and an External Donor on the Distribution of Active Sites According to Their Stereospecificity in Propylene Polymerization over TiCl 4 /MgCl 2 Catalysts with Different Titanium Content
Author(s) -
Nikolaeva Marina,
Mikenas Tatiana,
Matsko Mikhail,
Zakharov Vladimir
Publication year - 2016
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.201500486
Subject(s) - chemistry , catalysis , stereospecificity , polymerization , titanium , ziegler–natta catalyst , fractionation , magnesium , electron donor , polymer chemistry , inorganic chemistry , nuclear chemistry , organic chemistry , polymer
The data on content of individual fractions with different microtacticity for poly(propylene) (PP) samples produced over titanium–magnesium catalysts (TMCs) with composition TiCl 4 /MgCl 2 and different titanium contents (0.1 and 3.5 wt%), as well as on the effects of pretreatment of these catalysts with triethylaluminum and addition of an external electron donor to the polymerization reaction on the content of these fractions are obtained using preparative temperature rising elution fractionation. The TMC with low titanium content is found to contain more than 90% of aspecific sites and an insignificant number of sites with low isospecificity (IS 1 ) and isospecific sites (IS 2 ). Pretreatment of catalysts with triethylaluminum increases the contents of the IS 1 and IS 2 sites. Addition of an external donor results in a more noticeable increase in the contents of IS 1 and IS 2 sites and formation of highly isospecific IS 3 sites. The data on molecular weight and thermophysical properties of individual PP fractions with different microtacticity produced over catalysts with different compositions are obtained.