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Control of molecular weight and molecular weight distribution in ethylene polymerization with metallocene catalysts
Author(s) -
Han Taek Kyu,
Choi Hong Ki,
Jeung Dong Wook,
Ko Young Soo,
Woo Seong Ihl
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.1995.021960816
Subject(s) - metallocene , molar mass distribution , polymer chemistry , catalysis , polyethylene , polymerization , chemistry , post metallocene catalyst , organic chemistry , polymer
The molecular weight (MW) and the molecular weight distribution (MWD) of polyethylene (PE) prepared with various metallocene catalysts were investigated. The weight‐average molecular weight ( M w ) of PE prepared with dicyclopentadienyltitanium dichloride/aluminoxane (Cp 2 TiCl 2 /MAO) was about 4,0 · 10 5 , while that of PE obtained with dicyclopentadienylzirconium dichloride/aluminoxane (Cp 2 ZrCl 2 /MAO) is about 1,0 · 10 5 . PE of bimodal MWD was obtained with the mixed catalyst Cp 2 TiCl 2 /Cp 2 ZrCl 2 . Narrow MWD PE was obtained with the mixed catalyst Cp 2 ZrCl 2 /Et(ind) 2 ZrCl 2 , because each catalyst produced an M w of 1,0 · 10 5 . However, the change of temperature during the polymerization with the mixture Cp 2 ZrCl 2 /Et(ind) 2 ZrCl 2 produced PE with a bimodal MWD and a value of the ratio of weight‐ to number‐average molecular weights of M w / M n = 4.