Copolymerization of ethylene and propylene with (CpCH2CH2CH = CH2)(2)MCl2 (M = Zr, Hf) and Cp2ZrCl2 catalysts

(CpCH2CH2CH = CH2)(2)MCl2(M = Zr, Hf)/MAO and Cp2ZrCl2/MAO (Cp = cyclopenta dienyl; MAO = methylaluminoxane) catalyst systems have been compared for et hylene copolymerization to investigate the influence of the ligand and tran sition metal on the polymerization activity and copolymer properties. For b oth CH2CH2CH = CH2 substituted catalysts the catalytic activity decreased w ith increasing propene concentration in the feed. The activity of the hafno cene catalyst was 6 similar to 8 times lower than that of the analogous zir conocene catalyst, C-13 NMR analysis showed that the copolymer obtained usi ng the unsubstituted catalyst Cp2ZrCl2, has greater incorporatien of propen e than those produced by CH2CH2,CH = CH2 substituted Zr and Hf catalysts. T he melting point, crystallinity and the viscosity-average molecular weight of the copolymer decreased with an increase of propene concentration in the feed. Both CH2CH2CH = CH2 substituted Zr and Hf catalysts exhibit little o r no difference in the melting point and crystallinity of the produced copo lymers. However, there are significant differences between the two zirconoc ene catalysts. The copolymer produced by Cp2ZrCl2 catalyst have much lower T-m and X-c than those obtained with the (CpCH2CH2CH = CH2)(2)ZrCl2 catalys t. The density and molecular weight of the copolymer decreased in the order : (CpCH2CH2CH = CH2)(2)HfCl2>(CpCH2CH2CH = CH2)(2)ZrCl2>Cp2ZrCl2. The kinet ic behavior of copolymerizaton with Hf catalyst was found to be different f rom that with Zr catalyst.