ISSN:
1022-1352
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The initial polymerization stage of propene with a MgCl2-supported Ziegler catalyst after the pre-treatment with a Lewis base was examined as a study of the stereospecificity of the active sites precursors. A drastic depressing effect on the catalyst activity occurs, accompanied by an increase in stereospecificity, by the direct interaction of cyclohexylmethyldimethoxysilane (CMDMS) with the catalyst before the polymerization. The kinetic study of the polymerization indicated that the active sites concentration ([C*]) decreases drastically by the catalyst pre-treatment with CMDMS. On the other hand, the increase of propagation rate constant (kp) is relatively small and corresponds to the moderate increase of the mmmm pentad fraction. This is an indication that the interaction of the Lewis base with the active sites precursors prevents formation of the active sites and that inhibition occurs preferentially at the aspecific precursor.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
