Effect of the structure of alkyllithium on the polymerization kinetics of isoprene

1984 ◽  
Vol 49 (10) ◽  
pp. 2269-2274 ◽  
Author(s):  
U. D. N. Bajpai ◽  
Miroslav Kašpar ◽  
Jiří Trekoval
Keyword(s):  
Induction Period ◽  
Polymerization Kinetics ◽  
The Other ◽  
Kinetics Of Polymerization ◽  
Reaction Orders ◽  
Kinetics Of

The kinetics of polymerization of isoprene in benzene initiated with ethyl-, propyl-, butyl-, hexyl-, octyl-, 2-butyl-, 3-hexyl-, 2-octyl-, and 6-methylheptyllithium was investigated. With the exception of ethyllithium , a distinct initial induction period decreasing steeply with increasing concentration of the initiator was observed for all n-alkyllithium initiators. No induction period was observed with the other initiators. The reaction orders decreased at the highest concentrations for most of the initiators, sometimes even to negative values. In the case of ethyl-, 2-butyl- and octyl-lithium this phenomenon has not been observed in the range investigated.

The effect of electrondonors on the polymerization kinetics of isoprene

1980 ◽  
Vol 45 (12) ◽  
pp. 3338-3346
Author(s):  
Miroslav Kašpar ◽  
Jiří Trekoval
Keyword(s):  
Induction Period ◽  
Ethyl Ether ◽  
Reaction Order ◽  
Propagation Rate ◽  
Reaction Scheme ◽  
Polymerization Kinetics ◽  
Polymerization Rate ◽  
Constant Concentration ◽  
Initial Concentration ◽  
Kinetics Of

The effect of small additions of 1-octene, butyl ethyl ether and triethylamine on the polymerization kinetics of isoprene (2-methyl-1,3-butadiene) in benzene initiated with butyllithium was investigated by employing the GLC analysis. The addition of 1-octane was reflected only in a shorter induction period of the reaction; the effect on the propagation rate was insignificant. With the increasing amount of butyl ethyl ether, the polymerization rate increases linearly, while the reaction order with respect to the concentration of triethylamine is variable and increases from 0.33 to 0.66 with the increasing concentration of the initiator. For a constant concentration of triethylamine, the reaction order with respect to the initial concentration of the initiator was found to vary considerably, reaching even negative values. A reaction scheme was suggested, taking into account the competition between two different solvates of alkyllithium.

The Kinetics of Polymerization Reactions

1945 ◽  
Vol 18 (2) ◽  
pp. 223-235 ◽  
Author(s):  
G. Gee ◽  
H. W. Melville
Keyword(s):  
Half Life ◽  
Molecular Size ◽  
The Other ◽  
Chain Growth ◽  
Extreme Conditions ◽  
Kinetics Of Polymerization ◽  
Molecular Sizes ◽  
Mathematical Difficulties ◽  
The One ◽  
Kinetics Of

Abstract A general treatment of the kinetics of polymerization reactions is given to cover the two extreme conditions in which the lifetime of chain growth is (1) small, and (2) large compared with the half life of the monomer. Case (1) is considered on the basis of the assumption that the velocity coefficients do not depend on molecular size. Case (2) is considered for propagation coefficients which are on the one hand independent, and on the other hand dependent on molecular size. In addition, the distribution of molecular sizes is computed in those cases where the mathematical difficulties are not insurmountable. The application of these results to the analysis of polymerization reactions is discussed. The work described in this paper was completed when war broke out, and was to have been published as part of a book on polymerization processes. In view of the interest and development in these matters, it was felt desirable to give this account of these ideas now.

The polymerization of styrene by sulphuric acid - II. The kinetics of polymerization in 1:2-dichloroethane

1961 ◽  
Vol 263 (1312) ◽  
pp. 63-74 ◽  
Keyword(s):  
Rate Constants ◽  
Homogeneous Solution ◽  
The Other ◽  
Chain Reaction ◽  
Individual Values ◽  
Kinetics Of Polymerization ◽  
Temperature Range ◽  
Molecular Weights ◽  
Reaction Theory ◽  
Kinetics Of

The polymerization has been studied in homogeneous solution over the temperature range 0 to 35°C. At the upper temperatures the reactions are very fast; over the whole temperature range they are incomplete, giving limited yields of polymer which depend on the initial acid concentration, but not on that of the monomer. The results are described by the non­-stationary chain reaction theory derived in part I. Individual values of all the rate con­stants are obtained at 25°C, and ratios of rate constants at the other temperatures. The molecular weights are relatively low (< 20000) and determined by transfer rather than true termination processes.

INVESTIGATING THE EFFECT OF MCM-41 NANOPARTICLES ON THE KINETICS OF ATOM TRANSFER RADICAL POLYMERIZATION OF STYRENE

NANO ◽  
2013 ◽  
Vol 08 (02) ◽  
pp. 1350018 ◽  
Author(s):  
ABBAS ASFADEH ◽  
VAHID HADDADI-ASL ◽  
MEHDI SALAMI-KALAJAHI ◽  
MOHAMMADREZA SARSABILI ◽  
HOSSEIN ROGHANI-MAMAQANI
Keyword(s):  
Molecular Weight ◽  
Surface Modification ◽  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Polymerization Kinetics ◽  
Atom Transfer ◽  
Kinetics Of Polymerization ◽  
Kinetics Of ◽  
Mcm 41

Effect of pristine and modified MCM-41 on the kinetics of styrene atom transfer radical polymerization (ATRP) was studied using a double bound containing modifier at 110°C. Conversion, molecular weight and PDI were obtained during the polymerization reactions to study the polymerization kinetics. Addition of the both types of MCM-41 has resulted in inconsiderable variations on the kinetics of polymerization. A similar trend is observed for the molecular weight of the free chains; however, increasing MCM-41 content results in higher PDI values. Also, surface modification of MCM-41 results in lower polymerization rates. In the case of grafted chains, molecular weight and PDI values increase by increasing MCM-41 content.

scholarly journals Kinetics of Vinyl Polymerization of Methyl Methacrylate Initiated by Ce(IV)-Vanillin Redox System

2012 ◽  
Vol 9 (1) ◽  
pp. 430-434
Author(s):  
M. Palanivelu ◽  
K. E. N. Nalla Mohamed ◽  
T. Hidayathulla Khan ◽  
M. Prem Nawaz
Keyword(s):  
Sulfuric Acid ◽  
Methyl Methacrylate ◽  
Kinetic Scheme ◽  
Redox System ◽  
Kinetics Of Polymerization ◽  
Rate Of Polymerization ◽  
Reaction Orders ◽  
Higher Temperature ◽  
Increasing Temperature ◽  
Kinetics Of

The kinetics of polymerization of methyl methacrylate initiated by Ce(IV)-Vanillin redox system was studied in aqueous solution of sulfuric acid at 40°C. The rate of polymerization (Rp) and the reaction orders with respect to monomer, initiator and ligand have been determined and found to be 1.5, 0.5 and 0.5 respectively. The effect of concentration of sulfuric acid on the polymerization was also studied. The rate of polymerization was found to increase with increasing temperature 30–60°C and decreases at higher temperature (>60°C). The overall activation energy (Ea) was found to be 36.7 kJ/mol. A suitable kinetic scheme has been proposed.

The mechanism of the anionic coordination polymerization of isoprene

1980 ◽  
Vol 45 (9) ◽  
pp. 2391-2399 ◽  
Author(s):  
Miroslav Kašpar ◽  
Jiří Trekoval
Keyword(s):  
Chromatographic Method ◽  
Initial Period ◽  
Reaction Scheme ◽  
Polymerization Kinetics ◽  
Coordination Polymerization ◽  
Initial Concentration ◽  
The Cross ◽  
Gas Chromatographic Method ◽  
Kinetics Of

The polymerization kinetics of isoprene (2-methyl-1,3-butadiene) in benzene with butyllithium as the initiator was investigated by the gas chromatographic method. After completion of the initial period of the reaction, its order with respect to the initial concentration of initiator is negative at the concentrations of the latter between 0.01 and 0.25 mol/l, and positive at higher concentrations. A reaction scheme has been suggested with respect to the "cross" association of butyllithium and of the "living" oligoisoprene.

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