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To understand how the silyl-bridged metallocene catalysts rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2 behave against dienes under the same reaction condition because of its importance as a commercial polymerization catalyst and ethylene propylene diene monomers (EPDM). Adding diene depressed the catalytic activity, especially 5-ethylidene-2-norbornene (ENB) exerted the most substantial deactivation effect. Firstly, we examine the (ENB, vinyl norbornene (VNB) and 4-vinylcyclohexene (VCH)) non-conjugated and conjugated (isoprene (IP), butadiene (BD)) diene and address how polymerization catalysts behave against these dienes. For example, the catalytic activity was enhanced with IP and BD (3–3.3106 gm/mmolMt·h) compared to ENB, VNB and VCH. The VNB incorporation rate was prolonged (5.4 mol%), but with IP and BD, it was relatively moderate. E/P/IP and E/P/BD with higher incorporation of E produced a higher MW, which means that the chain transfer reaction with ethylene is slower than P. Secondly, we address how the dienes exocyclic and exocyclicπ bonds of non-conjugated and conjugated properties of IP and BD affect the kinetic measurements such as active centers [Zr]/[C*] fraction, EPDM chain propagation, termination, and isomerization. Finally, we compare [Zr]/[C*] and kpPE, kpP and kpDienes for different EPDM. After collecting these kinetic parameters, we can describe the mechanism's intricacy and the existence of considerable catalyst dormancy with dienes under identical reaction conditions. [ABSTRACT FROM AUTHOR]

Copolymerization of ethylene (E) and propylene (P) and their terpolymerizations with three kinds of diene (5-ethylidene-2-norbornene (ENB), 4-vinylcyclohexene (VCH) and 1,4-hexadiene (HD)) under 4 bar monomer pressure in n-heptane solution were studied. Two ansa-zirconocenes (rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2 (Mt-I) and rac-Et(Ind)2ZrCl2 (Mt-II)) activated by (Ph3C)B(C6F5)4/triisobutylaluminum were used as the catalyst, respectively. In general, addition of diene depressed the polymerization activity. ENB exerted the strongest deactivation effect on Mt-I, and HD caused the strongest deactivation on Mt-II. Among the two metallocenes, activity of Mt-I was more sensitive to the diene. Increasing diene concentration in the monomer feed caused lower propylene incorporation rate and shorter average length of polypropylene sequences, and the average length of polyethylene sequences was increased by adding more HD in E/P/HD terpolymerization with Mt-II. The Mt-II/borate catalyst showed high activity and diene incorporation rate for E/P/ENB terpolymerization. In contrast, Mt-I/borate catalyst showed high activity and propylene incorporation rate for E/P copolymerization, but was nearly inactive for E/P/ENB terpolymerization. [ABSTRACT FROM AUTHOR]

Ethylene-1-hexene copolymerization was catalyzed by TiCl4/diester/MgCl2 type Z-N catalyst activated by triethylaluminium (TEA), triisobutylaluminium (TIBA) or TEA/TIBA mixtures. Copolymerization activity decreased with increase of TIBA content in the cocatalyst. Each copolymer sample was fractionated into boiling n-heptane soluble and insoluble fractions. 1-Hexene content of the soluble fraction was 2 ∼ 6 times larger than that of the insoluble fraction. With introduction of TIBA in the cocatalyst, chemical composition distribution of the copolymer was broadened, attributable to increase of 1-hexene in the soluble fraction. Total number of active centers markedly decreased with increasing TIBA in cocatalyst, and active center number in the soluble fraction decreased more than that in the insoluble fraction. Rate constant of ethylene insertion (kpE) in the soluble fraction was much smaller than that of the insoluble fraction. Rate constant of 1-hexene insertion (kpH) of the soluble fraction became far larger than that of the insoluble fraction when TEA/TIBA ratio was lower than 80/20. In the presence of TIBA, only a part of active center precursors with stronger ability of incorporating 1-hexene were effectively activated in the soluble fraction. For the active centers in insoluble fraction, cocatalyst structure exerted more complicated effects on their activation. Active center models were proposed to explain the observed cocatalyst effects. [ABSTRACT FROM AUTHOR]