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Copolymerization of ethylene with 1‐hexene and 1‐octene: correlation between type of catalyst and comonomer incorporated
Author(s) -
Quijada Raul,
Dupont Jairton,
Miranda Márcia S. Lacerda,
Scipioni Rosângela B.,
Galland Griselda B.
Publication year - 1995
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.1995.021961210
Subject(s) - comonomer , metallocene , copolymer , ethylene , polymer chemistry , 1 hexene , post metallocene catalyst , catalysis , hexene , chemistry , cyclopentadienyl complex , olefin fiber , monomer , materials science , polymerization , organic chemistry , polymer
The behaviour of catalytic systems based on zirconium compounds for the copolymerization of ethylene with 1‐hexene and 1‐octene is reported. The metallocenes (CH 3 ) 2 SiCp 2 ZrCl 2 , Cp 2 ZrCl 2 (Cp = η 5 ‐cyclopentadienyl), C 2 H 4 [Ind] 2 ZrCl 2 and (Ind = η 5 ‐indenyl) were chosen for this study. The bridged catalysts, (CH 3 ) 2 SiCp 2 ZrCl 2 and C 2 H 4 [Ind] 2 ZrCl 2 , and the metallocene Cp 2 ZrCl 2 showed similar catalytic activities for home‐ and copolymerization of ethylene with 1‐hexene. 13 C NMR analysis showed that the composition of copolymerization products depends on the catalytic system, in other words, on the ligand structure of the transition metal. Copolymers obtained using the bridged catalysts have greater incorporation of comonomer. Thermal analysis and viscosity measurements demonstrated that an increase of the comonomer concentration reduces the melting point, the crystallinity and the molecular weight of the copolymer. Results from infrared spectroscopy showed that β‐elimination is one of the possible termination reactions. The monomer reactivity ratios r were determined for all catalytic systems using Fineman‐Ross and 13 C NMR methods. The values of r 1 ( M 1 = ethylene) and r 2 ( M 2 = α‐olefin) showed an effect of the type of metallocene and of α‐olefin on the structure of the copolymer obtained.