Effects of the type and concentration of alkylaluminum cocatalysts on the molar mass of polypropylene made with in situ supported metallocene catalysts

• Published in: Journal of applied polymer science 2005-03, Vol.95 (5), p.1050-1055
• Main Authors: Franceschini, Fernando C., Tavares, Tatiana T. da R., Greco, Paula P., Galland, Griselda B., dos Santos, João H. Z., Soares, João B. P.
• Format: Article
• Language: English
• Subjects: Applied sciences; catalysts; Exact sciences and technology; molecular weight distribution/molar mass distribution; Organic polymers; Physicochemistry of polymers; poly(propylene) (PP); Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.21229

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 13C‐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