KINETICS OF OLEFIN POLYMERIZATION CATALYZED BY VARIOUS ZIRCONOCENE ALUMINOXANE SYSTEMS AT LOW AL/ZR RATIOS/

Ethylene, propylene and 1-butene polymerization kinetics have been inv estigated in the presence of 16 zirconocene and ethylalumoxane derivat ives with various molecular masses and a molar ratio of Al/Zr=23-26. I t was found that zirconocene activity in combination with ethylalumoxa nes with molecular weight MW=880 (an oligomer with -[OAl(C2H5)]- unit number equal to 10) increases in series: Cp(Acac)(2)ZrCl < (Fulv)(2)Cp (2)Zr(2)Cl(2) < Cp(2)ZrMe(2) < (Fulv)(2)Cp(2)Zr(2)(0)Cl-2 < (Ind)(2)Zr Cl2 < (t-Bu(2)Cp)(2)ZrCl2 < Cp(2)ZrCl(2) < (t-BuCp)(2)ZrCl2 < (MeCp)(2 )ZrCl2 < (i-PrCp)(2)ZrCl2, where Fulv - fulvalene. With methylalumoxan e (MW = 1930, (-[OAl(CH3)]- unit number 31) the following series of zi rconocene activity was established: (MeCp)(2)ZrCl2 < (EtCp)(2)ZrCl2 < (PrCp)(2)ZrCl2 < (BuCp(2)ZrCl(2) < (i-PrCp)(2)ZrCl2 < (Cyclo-HexCp)(2) ZrCl2.