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Preparation of bimodal polypropylene in two‐step polymerization
Author(s) -
Abedi S.,
Hassanpour N.
Publication year - 2006
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.24210
Subject(s) - polymerization , polymer chemistry , chemistry , catalysis , polymer , molar mass distribution , polypropylene , gel permeation chromatography , solution polymerization , heptane , organic chemistry
Polymerization of propylene was carried out by using MgCl 2 .EtOH.TiCl 4 .DIBP.TEA.cHMDMS catalyst system in n ‐heptane, where MgCl 2 , EtOH, TiCl 4 , DIBP (diisobutyl phthalate), TEA (triethyl aluminum), and cHMDMS (cyclohexyl methyl dimethoxy silane) were support, ethanol for alcoholation, catalyst, external donor, cocatalyst (activator), and internal donor, respectively. The catalyst activity and polymer isotacticity were studied by measuring the produced polymer and its solubility in boiling n ‐heptane, respectively. The molecular weight and molecular weight distribution of the polymers were evaluated by gel permeation chromatography. Hydrogen was used for controlling the molecular weight. For producing the bimodal polypropylene, the polymerization was carried out in two steps (i.e., in the presence and absence of hydrogen). It was found that the catalyst showed high activity and stereoselectivity, on the other hand, bimodal polymer could simply be produced in two‐step polymerization by using MgCl 2 .EtOH.TiCl 4 .DIBP.TEA.cHMDMS catalyst system. Meanwhile, the effect of the step of the hydrogen adding on propylene polymerization was investigated. It was shown that the addition of hydrogen in the second step was more suitable. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1456–1462, 2006