It is demonstrated that the catalyst system bis(pentamethylcyclopentadienyl)-zirconium dichloride (Me 5 Cp) 2 ZrCl 2 -methylaluminoxane (MAO) is able to produce random copolymers of ethene and 1-hexene. The 1-hexene incorporation in the copolymers is extremely small. Even in the case of a molar ratio of [ethene] to [1-hexene] of 1/20 in the monomer feed, only 1.4 mol % 1-hexene are incorporated according to 13 C nuclear magnetic resonance (NMR) spectra. Nevertheless, the physical properties of the random copolymers change significantly in this small range of 1-hexene incorporation, from a high-density polyethene to a linear low-density polyethene. Thus, the melting temperature, the degree of crystallinity, the density and lamella thickness, and the long period of the alternating crystalline and amorphous regions decrease with increasing 1-hexene content in the random copolymers. Blends of high-density polyethene prepared with the system (Me 5 Cp) 2 ZrCl 2 -MAO and an elastomeric random copolymer of ethene and 1-hexene are phase-separated and show good compatibility, as demonstrated by transmission electron microscopy.
Carl Schorlemmer" Leuna-Merseburg, Sektion Chenlie, DDR -4200 Merseburg Der EinfluB von AlBr, auf die durch Tetrabenzyltitan katalysierte Polymerisation des Ethylens in Toluen bei 0°C wird untersucht. Es werden die optimalen Bedingungen der Bildung der polymerisationsaktiven Zentren, die Reaktionsordnung der Polymerisation in bezug auf die Titan-und Monomerkonzentration sowie die relative Ubertragungskonstante zum Ethylen bestinimt. Die kinetischen Daten werden mitgeteilt. Die Ergebnisse zeigen, da13 beim Molverhaltnis der Katalysatorkomponenten Al/Ti = 2 die Ketteniibertragung zum Ethylen auf die Molekulmasse der gebildeten Polymere den bestimmenden EinfluB ausiibt.
IIccAedosanus no Kunemme no~uwepuaayuu a m u~e n a 8 npucymcmsuu KamaJcumuuecicoii cucmewbi mempabenaunmuman -6pO&UCmbiii anlowunuiiH c c n e E o B a a o B n m H H e AlBr, H a ~a T a n 1 1 3 1 f p y e~y 1 0 Ti( CH,C,H,), ~O J I H M~~K I~~H I O ~T M J I~H~ B TOJIyOJIe npr? 0°C.
ZUSAMMENFASSUNG :Es wurde die Polymerisation des Vinylchlorids in Methylcyclohexan mit dem Katalysatorsystem TiC14-(C zH5) zAI(OCzHs)-Dioxan kinetisch untersucht. Die Abhangigkeit der Bruttopolymerisationgeschwindigkeit von der Katalysator-und Monomerkonzentration folgte der BeziehungDie Gesamtaktivierungsenergie betrug 8,3 kcal/Mol. Die Parameter der Copolymerisation von Vinylchlorid mit Styrol stimmen mit denen des radikalischen Mechanismus uberein.
SUMMARY:The polymerization of vinylchloride in methylcyclohexane with the catalyst
The kinetics of the ethylene polymerization catalyzed by Ti(CH2C6% ) , /TiBr, in toluene at 0 "C was studied. The effects of the mole ratio of the catalyst components and of the quantity of catalyst on the polymerization were investigated. Using the number of active centres, the rate constant of the propagation reaction was evaluated. The number of active centres was determined by quenching the polymerization with 1-butanol tritiated at the hydroxyl group.Compared with the kinetic data of the catalyst system Ti(CHzC6% ! , /AlBr,, the present results indicate that the nature of the cocatalyst mainly affects the conditions for the formation of active centres, but has no essential influence on their reactivity. These results support the concept of monometallic structure of the active centres in Ziegler-Natta catalysts.
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