ISSN:
1022-1352
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
The Zr surface loading from Cp2ZrCl2 toluene solutions on different kinds of commercial silicas (Grace 948, 952 and 956) was determined by Rutherford backscattering spectrometry. In all silicas, a saturation trend was observed with increasing amount of metal in the initial solution, the largest Zr loading value (1 wt.-%) being observed for silica Grace 948. Solid surface areas were determined by the BET method before and after metallocene immobilization, revealing that the values do not change after zirconocene impregnation. Two different kinds of cocatalyst were used, methylaluminoxane and trimethylaluminium. The aluminium loading on silica Grace 948 was determined using the 27Al(p,γ)28Si nuclear reaction and titrometry, both showing that methylaluminoxane leads to an “Al grafting” four times more efficient than does trimethylaluminium. Finally, the catalytic activity of these systems was tested in the polymerization of ethylene. The supported catalysts were shown to be active, specially using the low cost trimethylaluminium as a cocatalyst. The polymers obtained with the supported systems exhibited a higher molecular weight than those obtained with the homogeneous system.
Zusätzliches Material:
5 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/macp.1997.021981117
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