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Synthesis and characterization of branched polypropenes obtained by metallocene catalysis
Author(s) -
Arnold Manfred,
Bornemann Steffen,
Köller Frank,
Menke Tammo J.,
Kressler Jörg
Publication year - 1998
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/(sici)1521-3935(19981201)199:12<2647::aid-macp2647>3.0.co;2-z
Subject(s) - comonomer , propene , pentene , polymer chemistry , metallocene , copolymer , post metallocene catalyst , materials science , tacticity , octene , methylaluminoxane , polymer , polymerization , catalysis , chemistry , organic chemistry , composite material
The homopolymerization of propene, 4‐methyl‐1‐pentene, 1‐octene and the copolymerization of propene with 4‐methyl‐1‐pentene and 1‐octene, respectively, was carried out with the isospecific metallocene catalyst system rac ‐[(dimethylsilylene)bis(2‐methylbenzo(e)indenyl)]zirconium dichloride/methylaluminoxane at 30°C in toluene. By variation of the monomer ratio, it is possible to produce copolymers in the entire composition range. The activity, the amount of comonomer insertion, and the molecular masses obtained in the propene/1‐octene copolymerization are significantly higher compared to the respective values of the system propene/4‐methyl‐1‐pentene. It is possible to synthesize polymers with glass transition temperatures ranging from −65 up to 26°C. Whereas the incorporation of more than 20 mol‐% 1‐octene leads to amorphous polymers, the propene/4‐methyl‐1‐pentene copolymers with less than 15 and more than 60 mol‐% 4‐methyl‐1‐pentene are semicrystalline. All melting points vary in the range from 50 to 225°C. Wide angle X‐ray scattering measurements indicate an increase of the γ‐modification compared to the γ‐modification with increasing comonomer content and crystallization temperature. Typical supermolecular morphologies different from spherulites and known for the γ‐phase of the isotactic polypropene homopolymer are observed for the copolymers by polarized light microscopy.