Diene polymerizations with lanthanide coordination catalysts. II. The effects of catalytic system component types and polymerization conditions on molecular characteristics of 1,4-cis-Polybutadienes

Козлов, В. Г.; Marina, N. G.; Savel'eva, I. G.; Monakov, Yu. B.; Murinov, Yu. I.; Толстиков, Г. А.

doi:10.1016/s0020-1693(00)90142-7

Cited by 14 publications

(5 citation statements)

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“…In a general view the broad polymers MWD may be represented by 15 u ϭ PSX (1) where u, the polydispersity of the polymer, is the magnitude equal to the ratio of the weight-average molecular weight to the number-average molecular weight; P is the measure of the correlation between the polymerization reaction and diffusion limits; S is a factor depending on distribution of polymerization active centers (S 3 2 for the homogeneity of active sites); and X is a function of particle size distribution.…”

Section: Resultsmentioning

confidence: 99%

“…It has been established 1,2 that the use of various OACs define the values of constants of the reaction rate of transfer on OAC (K t Al ) and the values of the reaction rate of the propagation chain as well. The use of different OACs may influence the microstructure of formed polydienes.…”

Section: Introductionmentioning

confidence: 99%

“…Studies of diene polymerization on lanthanide catalytic systems have shown1–4 that the nature of the organoaluminum compound (OAC) had an essential influence both on catalytic system activity and the properties of the obtained polydienes. It has been established1, 2 that the use of various OACs define the values of constants of the reaction rate of transfer on OAC ( K

_{italict}^{italicAl}

) and the values of the reaction rate of the propagation chain as well. The use of different OACs may influence the microstructure of formed polydienes 3.…”

Section: Introductionmentioning

confidence: 99%

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The nature of the organoaluminum compound and the kinetic heterogeneity of active sites in lanthanide‐based diene polymerization

Sigaeva

Usmanov

Заиков

et al. 2003

J of Applied Polymer Sci

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ABSTRACT:The influence of the organoaluminum compound on the kinetic heterogeneity of active sites in lanthanide-based diene polymerization was investigated. It was found that the heterogeneity of investigated catalytic systems was shown in the existence of four types of active centers. They were formed at the beginning of the polymerization process and produced macromolecules with lengths that were definite for each type of active center. The nature of the organoaluminum compound greatly influenced the kinetic activity of the polymerization centers. A method for analyzing the curves' maximums of distribution on kinetic activity and the change in kinetic activity of every type of active centers is proposed. This method allows calculating the concentration values for each type of active center separately.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

_{italict}^{italicAl}

) and the values of the reaction rate of the propagation chain as well. The use of different OACs may influence the microstructure of formed polydienes 3.…”

Section: Introductionmentioning

confidence: 99%

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The nature of the organoaluminum compound and the kinetic heterogeneity of active sites in lanthanide‐based diene polymerization

Sigaeva

Usmanov

Заиков

et al. 2003

J of Applied Polymer Sci

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“…The study of diene polymerization on lanthanide catalytic systems showed [1][2][3][4] that the nature of organoaluminum compound (OAC) essentially had influence both on catalytic system activity and on properties of the received polydienes. It was established 1,2 that the use of various OAC-defined values of constants of transfer on OAC (k t Al ) reaction rate and the values of propagation chain reaction rate constants (k p ) as well.…”

Section: Introductionmentioning

confidence: 99%

“…It was established 1,2 that the use of various OAC-defined values of constants of transfer on OAC (k t Al ) reaction rate and the values of propagation chain reaction rate constants (k p ) as well. The use of different OACs may influence the microstructure of formed polydienes.…”

Section: Introductionmentioning

confidence: 99%

The influence of the nature of organoaluminum compound on kinetic heterogeneity of active sites in lanthanide‐based diene polymerization

Sigaeva¹,

Usmanov²,

Budtov³

et al. 2002

J of Applied Polymer Sci

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ABSTRACT:The influence of organoaluminum compound on kinetic heterogeneity of active sites in lanthanidebased diene polymerization was investigated. It was shown that heterogeneity of investigated catalytic systems was displayed in the existence of four types of active centers. They are formed at the beginning of the polymerization process and produce macromolecules with lengths that are definite for each type of active centers. The organoaluminum compound's nature greatly influences the kinetic activity of polymerization centers. The method of analysis of the curves' maximum distribution on kinetic activity and the change of kinetic activity of every active centers' type were proposed, which permits the calculation of values of concentration for each type of active center separately.

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Polymerization of butadiene and isoprene with the NdCl₃ · 3TBP‐TIBA catalyst system

Iovu

Hubca

Simionescu

et al. 1997

Angew. Makromol. Chem.

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The isoprene and butadiene polymerization processes with the NdCI, -3TBP-TIBA catalyst system (TBP: tributylphosphate, TIBA: triisobutylaluminium) are studied in detail using an original and very accurate experimental technique. The influences of the initial monomer concentration, the polymerization temperature and the catalyst and cocatalyst concentrations on the conversion, the average molar masses, the polydispersity and the microstructure of the polymers are discussed and explained considering the allylic complexes formed between the neodymium atom and the last monomer unit in the macromolecular chain. A first-order reaction with respect to the monomer was obtained. The calculated value of the activation energy (25.58 kT mol-') is lower than for classical Ziegler-Natta catalysts, thus demonstrating the higher catalytic activity of the NdC1, * 3TBP-TIBA catalyst system used. Two types of active centers are possible, as confirmed by GPC data. One of them, which includes aluminium, is more stable and favors the transformation from "anti" allylic units to "syn" allylic units. Thus, the 1,4-cis unit content of the prepared polymers is mainly determined by the TIBA concentration. The catalyst does not react by transfer reactions as TIBA does. The obtained conversions are always higher for butadiene than for isoprene due to a higher tendency of the former to complexate with the neodymium atom and forming allylic complexes. ZUSAMMENFASSUNG:Die Polymerisation von Isopren und Butadien mit dem NdCl, -3TBP-TIBA-Katalysatorsystem (TBP: Tributylphosphat, TIBA: Triisobutylaluminium) wurde mit einer sehr exakten experimentellen Technik detailliert untersucht. Die Einfliisse der Ausgangsmonomerenkonzentration, der Polymerisationstemperatur und der Katalysator-und Cokatalysatorkonzentrationen auf den Umsatz, die mittlere Molmasse, die Molmassenverteilung und die Mikrostruktur der Polymeren werden diskutiert und unter Beriicksichtigung der durch Neodym-Atome mit endstandigen Monomereinheiten der Polymerkette gebildeten Allyl-Komplexe erkliirt. Die Untersuchungen ergaben fur die Monomeren eine Reaktion erster Ordnung. Die berechnete Aktivierungsenergie (25.58 kJ mol-') ist niedriger als fur klassische Ziegler-Natta-Katalysatoren und zeigt die hohere katalytische Aktivitat des eingesetzten NdCl, -3TBP-TIBA-Katalysatorsystems. Die Ergebnisse von GPC-Messungen weisen auf zwei mogliche aktive Zentren hin, von denen jenes mit Aluminium eine hohere Stabilitat aufweist und die Umwandlung von "anti"-Allyl-Gruppen in "syn"-Allyl-Gruppen begunstigt. Der Gehalt der Polymeren an 1,4-cis-Einheiten wird hauptsachlich von der TIBA-Konzentration bestimmt. Der Katalysator geht jedoch keine Ubertragungsreaktionen ein, wie dies bei TIBA der Fall ist. Die Umsatze sind fur Butadien aufgrund der ausgepragteren Tendenz zur Bildung von Allyl-Komplexen mit Neodym-Atomen hoher als fur Isopren.

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Diene polymerizations with lanthanide coordination catalysts. II. The effects of catalytic system component types and polymerization conditions on molecular characteristics of 1,4-cis-Polybutadienes

Cited by 14 publications

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The nature of the organoaluminum compound and the kinetic heterogeneity of active sites in lanthanide‐based diene polymerization

The nature of the organoaluminum compound and the kinetic heterogeneity of active sites in lanthanide‐based diene polymerization

The influence of the nature of organoaluminum compound on kinetic heterogeneity of active sites in lanthanide‐based diene polymerization

Polymerization of butadiene and isoprene with the NdCl₃ · 3TBP‐TIBA catalyst system

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Diene polymerizations with lanthanide coordination catalysts. II. The effects of catalytic system component types and polymerization conditions on molecular characteristics of 1,4-cis-Polybutadienes

Cited by 14 publications

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The nature of the organoaluminum compound and the kinetic heterogeneity of active sites in lanthanide‐based diene polymerization

The nature of the organoaluminum compound and the kinetic heterogeneity of active sites in lanthanide‐based diene polymerization

The influence of the nature of organoaluminum compound on kinetic heterogeneity of active sites in lanthanide‐based diene polymerization

Polymerization of butadiene and isoprene with the NdCl3 · 3TBP‐TIBA catalyst system

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Polymerization of butadiene and isoprene with the NdCl₃ · 3TBP‐TIBA catalyst system