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Effects of the type and concentration of alkylaluminum cocatalysts on the molar mass of polypropylene made with in situ supported metallocene catalysts
Author(s) -
Franceschini Fernando C.,
Tavares Tatiana T. da R.,
Greco Paula P.,
Galland Griselda B.,
dos Santos João H. Z.,
Soares João B. P.
Publication year - 2005
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.21229
Subject(s) - methylaluminoxane , polymer chemistry , molar mass , polypropylene , polymerization , materials science , post metallocene catalyst , metallocene , gel permeation chromatography , polymer , zirconium , catalysis , differential scanning calorimetry , ziegler–natta catalyst , chemistry , organic chemistry , composite material , physics , metallurgy , thermodynamics
Propylene homopolymerizations were carried out with rac ‐dimethylsilylenebis(indenyl)zirconium dichloride, methylaluminoxane‐modified silica, and common alkylaluminum cocatalysts. Supported catalysts were prepared by the in situ immobilization technique. The effects of the type and concentration (Al/Zr = 40–1000) of alkylaluminum on the propylene polymerization were evaluated with triethylaluminum (TEA), isoprenylaluminum (IPRA), and triisobutylaluminum (TIBA) as cocatalysts. The polymers were analyzed by gel permeation chromatography, differential scanning calorimetry, and 13 C‐NMR. The polypropylene molar mass varied according to the nature of the alkylaluminum in the following order: TIBA > IPRA > TEA > no alkylaluminum. The polymers made with an in situ supported catalyst had lower crystallinities and melting points than the ones produced by homogeneous polymerization. The isotacticity was not affected by the polymerization conditions examined in this investigation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1050–1055, 2005