| Abstract: | Two new unbridged zirconocenes, bis(2,4,7-trimethyl indenyl)zirconium dichloride (Met-Ⅰ) andbis(2-methyl-4,7-diethyl indenyl)zirconium dichloride (Met-Ⅱ) were prepared in order to investigate thesteric effects of substituents on the nature of the catalysts for the polymerization of propylene. A mixture ofmethyl aluminoxane (MAO) and triisobutylaluminum [Al(iBu)3] was used as cocatalyst to activate thesecatalysts. The decrease in steric bulkiness of substituents at 4 and 7 positions of the indenyl ring resulted in an increase of both activity and molecular weight as well as the isotacticity. |
