Premium
Microstructural Characterization of Molecular Weight Fractions of Ethylene/1,7‐Octadiene Copolymers Made with a Constrained Geometry Catalyst
Author(s) -
Sarzotti Deborah M.,
Narayan Abhishek,
Whitney Philip M.,
Simon Leonardo C.,
Soares João B. P.
Publication year - 2005
Publication title -
macromolecular materials and engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.913
H-Index - 96
eISSN - 1439-2054
pISSN - 1438-7492
DOI - 10.1002/mame.200500064
Subject(s) - copolymer , methylaluminoxane , polymer chemistry , ethylene , materials science , polyethylene , polymer , solvent , molar mass distribution , polymerization , catalysis , linear low density polyethylene , organic chemistry , chemistry , metallocene , composite material
Summary: Ethylene was copolymerized with 1,7‐octadiene (OD) using a methylaluminoxane (MAO) activated constrained geometry catalyst (dimethylsilyl( N‐tert ‐butylamido)(tetramethylcyclopentadienyl)titanium dichloride; CGC‐Ti) at 140 °C in toluene. The polymerization activity increased with the addition of small amounts of OD, reached a maximum, and then decreased at higher OD concentrations. The vinyl‐bond content of the polymers increased with increasing diene in the feed. Increasing OD concentrations led to the production of long chain branched (LCB) polyethylene (PE). Both 1,3‐cycloheptane (CY 7 ) and 1,5‐cyclononane (CY 9 ) units were identified in the copolymers, with the dominant CY 9 structure accounting for approximately 53% percent of all rings. Selected copolymers were fractionated by molecular weight using a solvent/non‐solvent technique to obtain their detailed microstructure. The relative amounts of CY 7 and CY 9 structures were not a function of molecular weight. The number of vinyl functionalities decreased with increasing molecular weight, while the number of branches increased, indicating the incorporation of macromonomers with pendant or terminal vinyl groups.Molecular weight distributions of ethylene homopolymer and three fractions.