ISSN:
0887-624X
Keywords:
combination of ziegler-natta and metallocene catalysts
;
half metallocene catalysts supported on magnesium dichloride
;
activation by ordinary alkylaluminums
;
improvement of catalyst isospecificity by electron donors
;
microstructure of isotactic polypropene
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Several kinds of MgCl2-supported half titanocene (XTiCl3; X = cyclopentadienyl, pentamethylcyclopentadienyl, indenyl, and heptamethylindenyl) catalysts were prepared and applied to propene polymerization using Al(i-Bu)3a as cocatalyst. It was confirmed from the catalyst analysis that the ligand (X) is attached to titanium even after the reaction with Al(i-Bu)3. When polymerization was conducted without any external donor, those catalysts predominantly gave atactic PP. However, addition of a suitable monofunctional Lewis base like ethylbenzoate caused to change the stereospecificity of polymer from aspecific into highly isospecific. On the other hand, the use of a bifunctional donor like di-n-butylphthalate killed the activity almost completely. The isotactic PP was found to have a microstructure similar to that obtained with metallocene catalysts. © 1997 John Wiley & Sons, Inc.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
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