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 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.

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.

scholarly journals Raman Spectroscopic Characterization of Polymerization Kinetics of Cyanoacrylate Embolic Glues for Vascular Embolization

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3362
Author(s):  
Yongjiang Li ◽  
Lei Xiao ◽  
Zian Wang ◽  
Kejie Chen ◽  
Chundong Xue ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Polymerization Kinetics ◽  
Polymerization Rate ◽  
Polymerization Process ◽  
Slow Phase ◽  
Invasive Technique ◽  
Iodized Oil ◽  
Essential Information ◽  
Kinetics Of

Endovascular glue embolization is a minimally invasive technique used to selectively reduce or block the blood supply to specific targeted vessels. Cyanoacrylate glues, mixed with radiopaque iodized oil, have been widely used for vascular embolization owing to their rapid polymerization rate, good penetration ability and low tissue toxicity. Nevertheless, in clinical practice, the selection of the glue–oil proportion and the manual injection process of mixtures are mostly based on empirical knowledge of operators, as the crucial physicochemical effect of polymerization kinetics has rarely been quantitatively investigated. In this study, the Raman spectroscopy is used for studying the polymerization kinetics of n-butyl-cyanoacrylate-based glues mixed with an iodized oil. To simulate the polymerization process during embolization, glue–oil mixtures upon contact with a protein ionic solution mimicking blood plasma are manually constructed and their polymerization kinetics are systematically characterized by Raman spectroscopy. The results demonstrate the feasibility of Raman spectroscopy in the characterization of polymerization kinetics of cyanoacrylate-based embolic glues. The polymerization process of cyanoacrylate-based mixtures consists of a fast polymerization phase followed by a slow phase. The propagation velocity and polymerization time primarily depend on the glue concentrations. The commonly used 50% mixture polymerizes 1 mm over ∼21.8 s, while it takes ∼51 min to extend to 5 mm. The results provide essential information for interventional radiologists to help them understand the polymerization kinetics of embolic glues and thus regulate the polymerization rate for effective embolization.

Synthesis and Polymerization Kinetics of PMMA in Imidazolium Ionic Liquids

2013 ◽  
Vol 423-426 ◽  
pp. 528-531
Author(s):  
Pei Wang ◽  
Yuan Liu ◽  
Wen Su ◽  
Lian Liu
Keyword(s):  
Molecular Weight ◽  
Rate Constant ◽  
Average Molecular Weight ◽  
Propagation Rate ◽  
Polymerization Kinetics ◽  
Growth Rate Constant ◽  
Weight Average Molecular Weight ◽  
Propagation Rate Constant ◽  
Kinetics Of ◽  
Chain Propagation Rate

Polymerization of high molecular weight PMMA was achieved in [BMIM]PF4at reaction temperature 60oC, 65°C and 70 °C, reaction time 60min. The data including the yield, molecular weight and molecular weight distribution of PMMA were analysized. The results showed that the weight average molecular weight of PMMA in [BMIM]PF4is up to 275867, respectively 4 and 7 times of molecular weight in cyclohexane and toluene. Secondly, the polymerization kinetics of PMMA in [BMIM]PF4were tested, the apparent chain propagation rate constant of PMMA are 0.93×104,1.11 ×104and 14.1×104in 60 °C, 65°C and 70 °C. Compared with the growth rate constant in toluene, the polymerization rate constant PMMA in the ionic liquid increased by 4~7 times.

Kinetics of Alkyllithium Initiated Polymerizations

1970 ◽  
Vol 43 (1) ◽  
pp. 22-73 ◽  
Author(s):  
H. L. Hsieh ◽  
W. H. Glaze
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Propagation Rate ◽  
Polymerization Rate ◽  
Vinyl Monomers ◽  
Polar Solvents ◽  
Organolithium Compounds ◽  
Rate Of Polymerization ◽  
Kinetics Of

Abstract The kinetics of alkyllithium initiated polymerizations is reviewed for publication in Rubber Reviews for 1970. It contains nine sections: introduction, the structure of organolithium compounds, rate of polymerization, rate of propagation, rate of initiation, molecular weight and molecular weight distribution, polymerization of diene and vinyl monomers in polar solvents, copolymerizations, and polymerizations of polar monomers. A total of 205 references are cited.

The Kinetics of Magnesium Carbonate Crystallization for Traditional Salt Production Wastewater Recovery

2019 ◽  
Vol 964 ◽  
pp. 136-144
Author(s):  
Mirna Apriani ◽  
Wahyono Hadi ◽  
Ali Masduqi
Keyword(s):  
Electrical Conductivity ◽  
Induction Period ◽  
Magnesium Chloride ◽  
Batch Reactor ◽  
Magnesium Carbonate ◽  
Conductivity Method ◽  
Monitoring Method ◽  
Initial Concentration ◽  
Kinetics Of ◽  
Electrical Conductivity Method

The kinetics of crystallization of magnesium carbonate (nesquehonite) at room temperature (27°C) has been examined using an electrical conductivity method during process of nucleation. Magnesium carbonate hydrate from a reaction of magnesium chloride (MgCl2) and sodium carbonate (Na2CO3) in supersaturated condition was analyzed. Variations of batch reactor experimental are magnesium chloride initial concentration (500-3.000 mg/L) and operating pH (8-14). In this paper, we studied the crystallization kinetics of magnesium carbonate via an electrical conductivity method, a concentration monitoring method. By monitoring electrical conductivity during the solution reaction process, changes in [Mg2+] can be measured and an induction period of nucleation could be determined. Crystal has been formed was confirmed with powder X-ray Diffractometer (XRD) analyses. The results show that magnesium carbonate is formed during operating condition pH 10 with magnesium chloride initial concentration 3.000 mg/L. The nucleation process of magnesium carbonate crystallization can be represented by second-order reaction equation with R2 is 0.8. The induction period of magnesium carbonate crystallization is 50 second.

Synthesis and Polymerization Kinetics of PMMA in [BMIM]BF6 Imidazolium Ionic Liquids

2013 ◽  
Vol 395-396 ◽  
pp. 411-414 ◽  
Author(s):  
Pei Wang ◽  
Yuan Liu ◽  
Wen Su ◽  
Lian Liu
Keyword(s):  
Molecular Weight ◽  
Rate Constant ◽  
Average Molecular Weight ◽  
Propagation Rate ◽  
Polymerization Kinetics ◽  
Growth Rate Constant ◽  
Weight Average Molecular Weight ◽  
Propagation Rate Constant ◽  
Kinetics Of ◽  
Chain Propagation Rate

Polymerization of high molecular weight PMMA was achieved in [BMIPF6by contrasted in cyclohexane, toluene solvent at reaction temperature 60 C, 65C and 70 C, reaction time 60min. The data including the yield, molecular weight and molecular weight distribution of PMMA were analysized in 3 kind of solvent. The results showed that the weight average molecular weight of PMMA in [BMIPF6is up to 730000, respectively 7 and 10 times of molecular weight in cyclohexane and toluene. Secondly, the polymerization kinetics of PMMA in [BMIPF6were tested, the apparent chain propagation rate constant of PMMA are 10.7×10412.9 ×104and 19.9×104in 60 C, 65C and 70 C. Compared with the growth rate constant in toluene, the polymerization rate constant PMMA in the ionic liquid increased by 5~10 times.

Carbon tetrachloride biodegradation in a fixed-biofilm reactor and its kinetic study

1998 ◽  
Vol 38 (8-9) ◽  
pp. 155-162 ◽  
Author(s):  
G. Jin ◽  
A. J. Englande
Keyword(s):  
Carbon Tetrachloride ◽  
Continuous Flow ◽  
Model Comparison ◽  
Biofilm Reactor ◽  
Pseudomonas Cepacia ◽  
Initial Concentration ◽  
Biphasic Model ◽  
Providencia Stuartii ◽  
Kinetics Of ◽  
Fixed Biofilm

Kinetics of Carbon Tetrachloride biodegradation are evaluated in a continuous-flow fixed-biofilm reactor with controlled initial redox potential. The column was seeded with a mixed culture of indigenous microorganisms Pseudomonas cepacia and Providencia stuartii. The fixed biofilm reactor exhibited 98%–99.9% biodegradation of CT introduced into the reactor at an initial concentration of about 200 μg/l for retention times of 1 to 4 days respectively. Four models were employed to evaluate the kinetics of CT biodegradation. These included: Eckenfelder (1989), Arvin (1991), Bouwer and McCarty (1985) and a biphasic model. Comparison of calculated results with observed results between these models agreed very closely to each other (0.968 < R2 < 0.999). Predicted performance was best described by the model of Bouwer and McCarty (1985). However, the biphasic and Eckenfelder models provided excellent correlations and were much simpler to apply. The biphasic model yielded very good correlations of the data for all detention times evaluated; whereas, the Eckenfelder model effected comparable results only at the longer retention times studied.

scholarly journals Synthesis and Polymerization Kinetics of Rigid Tricyanate Ester

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1686
Author(s):  
Andrey Galukhin ◽  
Roman Nosov ◽  
Ilya Nikolaev ◽  
Elena Melnikova ◽  
Daut Islamov ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Single Step ◽  
Polymerization Kinetics ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Diffusion Controlled ◽  
Polymerization Product ◽  
The One ◽  
Kinetics Of

A new rigid tricyanate ester consisting of seven conjugated aromatic units is synthesized, and its structure is confirmed by X-ray analysis. This ester undergoes thermally stimulated polymerization in a liquid state. Conventional and temperature-modulated differential scanning calorimetry techniques are employed to study the polymerization kinetics. A transition of polymerization from a kinetic- to a diffusion-controlled regime is detected. Kinetic analysis is performed by combining isoconversional and model-based computations. It demonstrates that polymerization in the kinetically controlled regime of the present monomer can be described as a quasi-single-step, auto-catalytic, process. The diffusion contribution is parameterized by the Fournier model. Kinetic analysis is complemented by characterization of thermal properties of the corresponding polymerization product by means of thermogravimetric and thermomechanical analyses. Overall, the obtained experimental results are consistent with our hypothesis about the relation between the rigidity and functionality of the cyanate ester monomer, on the one hand, and its reactivity and glass transition temperature of the corresponding polymer, on the other hand.

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