Relation between the Nature of the Components of Titanium-containing Ziegler Systems and Their Activity and Stereospecificity in the Polymerisation of Dienes

Marina, N. G.; Monakov, Yurii B; Rafikov, S. R.; Ponomarenko, V. I.

doi:10.1070/rc1983v052n05abeh002828

Cited by 15 publications

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“…These data would enable substantial progress in the study of mechanisms of ionic-coordination polymerization and the structure of active sites. Therefore, the purpose of this study was to obtain the distributions of the active sites of the ionic-coordination titanium-containing catalytic systems of butadiene polymerization by stereoregulating ability and kinetic activity.Butadiene polymerization was studied in the presence of the TiCl 4 -Al( i -C 4 H 9 ) 3 catalytic system, which allows one to prepare polybutadienes with microstructures varying over a broad range by varying the polymerization conditions [9].The synthesis of polybutadiene was conducted in toluene at 25 ± 1°ë under conditions excluding the presence of impurities, moisture, or air in the reaction vessels. First, an organic derivative of a main-group metal, Al( i -C 4 H 9 ) 3 , was introduced into a butadiene solution, and, after that, a transition metal compound, TiCl 4 , was added.…”

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Kinetic Heterogeneity and Distribution of the Active Sites of the TiCl4-Al(i-C4H9)3 Catalytic System by Stereoregulating Ability in Butadiene Polymerization

et al. 2005

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A main problem in the theory and practice of ioniccoordination polymerization is the structure of active sites [1][2][3] and their stereospecific and kinetic heterogeneity. Recent publications [4][5][6] have confirmed the earlier assumptions [7,8] on the multicenter structure of the ionic-coordination catalytic systems in the polymerization of dienes. Solution of the inverse problems of molecular weight distributions (MWDs) exemplified by lanthanide-and vanadium-containing catalytic systems gave distributions of active sites by kinetic activity and demonstrated the presence of several types of active sites differing in the kinetic parameters of the processes involving these sites. No data on the distribution of active sites by stereoregulating ability in diene polymerization are available. These data would enable substantial progress in the study of mechanisms of ionic-coordination polymerization and the structure of active sites. Therefore, the purpose of this study was to obtain the distributions of the active sites of the ionic-coordination titanium-containing catalytic systems of butadiene polymerization by stereoregulating ability and kinetic activity.Butadiene polymerization was studied in the presence of the TiCl 4 -Al( i -C 4 H 9 ) 3 catalytic system, which allows one to prepare polybutadienes with microstructures varying over a broad range by varying the polymerization conditions [9].The synthesis of polybutadiene was conducted in toluene at 25 ± 1°ë under conditions excluding the presence of impurities, moisture, or air in the reaction vessels. First, an organic derivative of a main-group metal, Al( i -C 4 H 9 ) 3 , was introduced into a butadiene solution, and, after that, a transition metal compound, TiCl 4 , was added. The monomer concentration C m was 2 mol/L and the catalyst concentration C Ti was 0.01-0.005 mol/L for the molar ratio Al/Ti = 2, which corresponds to the highest activity of the catalytic system.The polymer microstructure (the content of 1,4-cis , 1,4-trans , and 1,2 units) was calculated from the relative intensity of the IR absorption bands at 740, 970, and 910 cm -1 . The spectra were recorded on a Specord M-80 spectrophotometer.The molecular weights ( M w and M n ) and the MWD of polybutadiene were determined on a Waters GPS 2000 gel chromatograph at 80°ë using toluene as the eluent. A three-column system packed with styrogel was calibrated against polystyrene standards with a narrow MWD ( M w / M n ≤ 1.2 ) using the universal Benoit dependence and an equation relating the MW of 1,4-trans -polybutadiene to the intrinsic viscosity [10]. The MWD curves were corrected with application of the instrument broadening correction as described previously [11].The polymer was fractionated by fractional precipitation with methanol from a 1% toluene solution followed by reprecipitation.The kinetic heterogeneity of the catalytic system was estimated by solving the inverse problem of MWD formation by the Tikhonov regularization method [3][4][5][12][13][14].In all cases, the polymers had bimodal ...

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“…Butadiene polymerization was studied in the presence of the TiCl 4 -Al( i -C 4 H 9 ) 3 catalytic system, which allows one to prepare polybutadienes with microstructures varying over a broad range by varying the polymerization conditions [9].…”

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confidence: 99%

Kinetic Heterogeneity and Distribution of the Active Sites of the TiCl4-Al(i-C4H9)3 Catalytic System by Stereoregulating Ability in Butadiene Polymerization

et al. 2005

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“…O valor da relação Al/Ti que produz a atividade máxima é variável de acordo com os resultados apresentados por diferentes autores [10,17] . O rendimento da polimerização aumenta rapidamente com a razão Al/Ti, atinge um valor máximo, em razão molar dependente do tipo de alquil-alumínio utilizado [18,19] , e decresce à medida que esta aumenta. O rendimento também é função da concentração de titânio, em baixas concentrações cresce rapidamente com o aumento desta e tende a um valor constante para concentrações mais altas [20] .…”

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Polimerização 1,4 - cis de butadieno com o sistema catalítico tetracloreto de titânio/triisobutilalumínio/iodo

Pires¹,

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2000

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Foi utilizado o sistema catalítico tipo Ziegler-Natta modificado, constituído por TiCl4/I2/Al(i-Bu)3 para a síntese de polibutadieno com alto teor de unidades 1,4-cis. Foi estudada a influência da variação da composição do sistema catalítico e da temperatura reacional na atividade catalítica, no massa molar e na microestrutura do polibutadieno. Os polímeros foram caracterizados por espectroscopia na região do infravermelho, cromatografia por exclusão por tamanho e calorimetria diferencial de varredura. Foi obtido polibutadieno com até 92% de unidades 1,4-cis e baixo teor de gel. A massa molar ponderal média variou, com a composição do sistema catalítico e com a temperatura reacional, na faixa de 3 a 50 x 10(4) e a polidispersão variou na faixa de 1,8 a 3,3. A atividade catalítica máxima foi obtida para as razões molares Al/Ti = 5 e I2/Ti = 2.

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Higher aluminum trialkyls and magnesium aluminum alkyls as components of zioegler–natta catalysts

Gaponik¹,

Antipova²,

Morozova³

et al. 1989

J of Applied Polymer Sci

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SynopsisMagnesium aluminum alkyls containing higher (C,-C,,,) radicals were studied as components of Ziegler-Natta catalysts in styrene polymerization. The effects of alkyl radical length and MgR, contents in the components mentioned on the degree of TiCl, reduction and stereospecific activity of the catalysts were investigated. The components studied exhibited high reducing (for TiCl, ) and catalytic activities. Molecular weight of the synthesized isotactic polystyrene was abnormally high.

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Relation between the Nature of the Components of Titanium-containing Ziegler Systems and Their Activity and Stereospecificity in the Polymerisation of Dienes

Cited by 15 publications

References 4 publications

Kinetic Heterogeneity and Distribution of the Active Sites of the TiCl4-Al(i-C4H9)3 Catalytic System by Stereoregulating Ability in Butadiene Polymerization

Kinetic Heterogeneity and Distribution of the Active Sites of the TiCl4-Al(i-C4H9)3 Catalytic System by Stereoregulating Ability in Butadiene Polymerization

Polimerização 1,4 - cis de butadieno com o sistema catalítico tetracloreto de titânio/triisobutilalumínio/iodo

Higher aluminum trialkyls and magnesium aluminum alkyls as components of zioegler–natta catalysts

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