Molecular weight phenomena at high conversions in the Ziegler–Natta polymerization of butadiene

Honig, J. A. J.; Burford, R. P.; Chaplin, R.P.

doi:10.1002/pol.1984.170220624

Cited by 5 publications

(3 citation statements)

References 24 publications

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“…Additionally, we have studied the effect of catalyst concentration, water:alkylaluminum ratio (W/Al), and chain transfer agent on polymerization of BD in cyclohexane and toluene. The selected studies in toluene reported by Honig et al are shown to be in agreement with our values. , Noticeably, important variables like water:alkylaluminum ratio, molecular weight, polydispersity index (PDI), and rate constants are studied as valuable information for butadiene polymerization.…”

Section: Introductionsupporting

confidence: 90%

“…11 It can be seen that the polymerization rate follows the order cyclohexane > toluene > EB, in reverse order with their π-electron density. Reaction is considered to be pseudo-first-order in toluene according to Honig et al 28,29 This also signifies that the parameter related to π-donation ability of the solvent is the determinant factor for controlling the reaction progress.…”

Section: Kinetic Behavior In Differentmentioning

confidence: 99%

“…The selected studies in toluene reported by Honig et al are shown to be in agreement with our values. 28,29 Noticeably, important variables like water:alkylaluminum ratio, molecular weight, polydispersity index (PDI), and rate constants are studied as valuable information for butadiene polymerization.…”

Section: Introductionmentioning

confidence: 99%

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Retarding Effect of Aromatic Solvents on Cobalt(II)-Based Catalyst System during Synthesis of Highcis-1,4-Polybutadiene

Singh¹,

Modi²,

Subrahmanyam³

et al. 2010

Ind. Eng. Chem. Res.

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The present study discloses the influence of aliphatic (cyclohexane) and aromatic solvents with different π-electron densities viz. toluene, o-xylene, ethylbenzene (EB), and p-diethylbenzene (PDEB) on the cobalt-catalyzed high cis-polymerization of 1,3-butadiene. Comparative study in cyclohexane and toluene has been conducted in view to understand the effect of solvent on catalyst reactivity, molecular weight of the polymer, and polymerization kinetics. At given reaction conditions conversion is highest (68%) in cyclohexane, followed by toluene (27%) and EB (8%). Respective polymerization rate constants are found to be 0.0170, 0.0020, and 0.0008 min−1. Higher viscosity average molecular weight (M) of polymer observed in toluene (M = 4.68 × 105) compared to that in cyclohexane (M = 2.37 × 105) indicates that the presence of lower number of active sites leads to higher molecular weight. Cyclohexane shows activity at a lower water:alkylaluminum ratio than does toluene; as the π-electron of toluene reduces the Lewis acidity of hydrolyzed diethylaluminum chloride (DEAC) more than cyclohexane, where influence of π-electron is absent. The effect of different solvents has also been demonstrated by respective shifting of wavelength (λ) of solvent π → π*, cobalt 4A2 → 4T1(P), as well as 4T1 g (F) → 4T1 g (P) and activated butadienyl π(HOMO) → π*(LUMO) transitions.

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Section: Introductionsupporting

confidence: 90%

Section: Kinetic Behavior In Differentmentioning

confidence: 99%

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Retarding Effect of Aromatic Solvents on Cobalt(II)-Based Catalyst System during Synthesis of Highcis-1,4-Polybutadiene

Singh¹,

Modi²,

Subrahmanyam³

et al. 2010

Ind. Eng. Chem. Res.

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Modeling of butadiene polymerization using cobalt octoate/DEAC/water catalyst

Estrada

Hsu

Bacon

1988

J of Applied Polymer Sci

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SynopsisTwo-level fractional factorial designs were employed to study the solution polymerization of butadiene in a batch reactor using cobalt octoate/DEAC/water as catalyst. Conversion and molecular weight data obtained as functions of time were used to develop a kinetic model, and the estimated kinetic parameters were correlated empirically with four operating variables: temperature and concentrations of cobalt octoate, DEAC, and water. The experimental data indicate that a t high water concentration a significant amount of oligomers is formed during early stages of polymerization, and the molecular weight of polymer increases with time. Analysis of the data suggests instantaneous initiation, first order propagation with cobalt and monomer, and transfer to monomer. Models which do not take account of the branching are shown to be incapable of fitting data for both a,, and Mu. The catalyst decay seems to follow a first-order mechanism, but the evidence is somewhat inconclusive. INTRODUCTIONCis-polybutadiene can be prepared using Ziegler-Natta catalysts of titanium or cobalt compounds with aluminum alkyls. A cobalt catalyst usually has the advantage of high solubility in organic solvents and as a result is more efficient in terms of polymer yield per unit mass of catalyst used.Several different cobalt salts have been reported to be effective for the 1,4-cis addition polymerization of butadiene, and cobalt salts of fatty acids have been used successfully in the commercial production of polybutadiene. The most common of these is cobalt octoate with diethyl aluminum chloride (DEAC) and water as cocatalysts. Despite its practical significance, however, the kinetics of this catalyst system have not been studied extensively.Among the few publications on this subject appearing in the open literature is Gippin's' investigation of the kinetic behavior of cobalt octoate and the effects of water and its substitutes, such as cumene hydroperoxide, elemental bromine, and tert-butyl alcohol, on the activity of the catalyst and the quality of polymer produced after 19 h of reaction at 5°C. Gippin believed that part of the DEAC reacts with water or its substitutes to produce higher acid derivatives. A possible reaction of DEAC with those compounds is the dialkylation of DEAC by the substitution of a reactive electronegative group for one ethyl group.Recently Honig et a1.2.S reported kinetic data on butadiene polymerization with a cobalt octoate-DEAC catalyst. The results and the proposed mechanism formed the basis for a kinetic model developed by Hamielec and co-worker~,~ who used an empirical factor to take account of the efficiency of In this work a batch reactor was used for polymerization. Under preselected operating conditions experiments were carried out according to two-level fractional factorial designs. The rate and average molecular weights were measured as functions of time to develop a kinetic model and estimate its kinetic parameters. The effects of temperature and concentration of DEAC, and of water, on those parame...

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An investigation of supported Ziegler-Natta catalysts for the polymerization of butadiene

Chaplin

Burford

Tory

et al. 1987

Polymer

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Molecular weight phenomena at high conversions in the Ziegler–Natta polymerization of butadiene

Cited by 5 publications

References 24 publications

Retarding Effect of Aromatic Solvents on Cobalt(II)-Based Catalyst System during Synthesis of Highcis-1,4-Polybutadiene

Retarding Effect of Aromatic Solvents on Cobalt(II)-Based Catalyst System during Synthesis of Highcis-1,4-Polybutadiene

Modeling of butadiene polymerization using cobalt octoate/DEAC/water catalyst

An investigation of supported Ziegler-Natta catalysts for the polymerization of butadiene

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