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.

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.

scholarly journals Kinetic and Thermal Study of Ethylene and Propylene Homo Polymerization Catalyzed by ansa-Zirconocene Activated with Alkylaluminum/Borate: Effects of Alkylaluminum on Polymerization Kinetics and Polymer Structure

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 268
Author(s):  
Amjad Ali ◽  
Nadeem Muhammad ◽  
Shahid Hussain ◽  
Muhammad Imran Jamil ◽  
Azim Uddin ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Propagation Rate ◽  
Propylene Polymerization ◽  
Chain Growth ◽  
Molar Ratios ◽  
Propagation Rate Constant ◽  
Olefin Polymerizations ◽  
Kinetics Of ◽  
Polymer Chain Growth ◽  
Chain Propagation Rate

The kinetics of ethylene and propylene polymerization catalyzed by homogeneous metallocene were investigated using 2-thiophenecarbonyl chloride followed by quenched-flow methods. The studied metallocene catalysts are: rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2 (Mt-I), rac-Et(Ind)2ZrCl2 (Mt-II) activated with ([Me2NPh][B(C6F5)4] (Borate-I), [Ph3C][B(C6F5)4] (Borate-II), and were co-catalyzed with different molar ratios of alkylaluminum such as triethylaluminium (TEA) and triisobutylaluminium (TIBA). The change in molecular weight, molecular weight distribution, microstructure and thermal properties of the synthesized polymer are discussed in detail. Interestingly, both Mt-I and Mt-II showed high activity in polyethylene with productivities between 3.17 × 106 g/molMt·h to 5.06 × 106 g/molMt·h, activities were very close to each other with 100% TIBA, but Mt-II/borate-II became more active when TEA was more than 50% in cocatalyst. Similarly, Polypropylene showed the highest activity of 11.07 106 g /molMt·h with Mt-I/Borate-I/TIBA. The effects of alkylaluminum on PE molecular weight were much more complicated; MWD curve changed from mono-modal in Mt-I/borate-I/TIBA to bimodal type when TIBA was replaced by different amounts of TEA. In PE, the active center fractions [C*]/[Zr] of Mt-I/borate were higher than that of Mt-II/borate and average chain propagation rate constant (kp) value slightly decreased with the increase of TEA/TIBA ratio, but the Mt-II/borate systems showed higher kp 1007 kp (L/mol·s). In PP, the Mt-I/borate presented much higher [C*]/[Zr] and kp value than the Mt-II. This work also extend to investigate the mechanistic features of zirconocenes catalyzed olefin polymerizations that addressed the largely unknown issues in zirconocenes in the distribution of the catalyst, between species involved in polymer chain growth and dormant state. In both metallocene systems, chain transfer with alkylaluminum is the dominant way of chain termination. To understand the mechanism of cocatalyst effects on PE Mw and (MWD), the unsaturated chain ends formed via β-H transfer have been investigated by 1H NMR analysis.

Halogenation with N-haloamines in strong acids. II. Kinetics and rate constants

1970 ◽  
Vol 48 (4) ◽  
pp. 554-560 ◽  
Author(s):  
J. Spanswick ◽  
K. U. Ingold
Keyword(s):  
Rate Constant ◽  
Decanoic Acid ◽  
Propagation Rate ◽  
The Self ◽  
Radical Chain ◽  
Rate Of Reaction ◽  
Propagation Rate Constant ◽  
Strong Acids ◽  
Kinetics Of ◽  
Rate Controlling Step

The kinetics of the radical chain chlorination of decanoic acid by N-chlorodimethylamine and N-chloropiperidine in 2 and 4 M H2SO4 in acetic acid have been examined at 30°. The rate of reaction is proportional to the decanoic acid concentration and to the square root of the rate of chain initiation. The rate controlling step for propagation involves the attack of an aminium radical on decanoic acid, and termination involves the self-reaction of two aminium radicals. The latter reaction may involve the prior, rapid deprotonation of one or both radicals. The propagation rate constant has been estimated to be in the range 7 × 102 to 1 × 104 M−1 s−1 and the termination rate constant to be in the range 6 × 106 to 5 × 107 M−1 s−1.

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.

Metathesis Polymerization of Phenylacetylene by Tungsten Aryloxo Complexes

1995 ◽  
Vol 60 (3) ◽  
pp. 489-497 ◽  
Author(s):  
Hynek Balcar ◽  
Jan Sedláček ◽  
Marta Pacovská ◽  
Vratislav Blechta
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Induction Period ◽  
Average Molecular Weight ◽  
Molar Fraction ◽  
Molar Ratio ◽  
Weight Average Molecular Weight ◽  
Polymer Yield ◽  
Positive Effect ◽  
Ligand Addition

Catalytic activity of the tungsten aryloxo complexes WCl5(OAr) and WOCl3(OAr), where Ar = 4-t-C4H9C6H4, 2,6-(t-C4H9)2C6H3, 2,6-Cl2C6H3, 2,4,6-Cl3C6H2, and 2,4,6-Br3C6H2 in polymerization of phenylacetylene (20 °C, monomer to catalyst molar ratio = 1 000) was studied. The activity of WCl5(OAr) as unicomponent catalysts increases with increasing electron withdrawing character of the -OAr ligand. Addition of two equivalents of organotin cocatalysts (Me4Sn, Bu4Sn, Ph4Sn, Bu3SnH) to WCl5(O-C6H2Cl3-2,4 ,6) has only slight positive effect (slightly higher polymer yield and/or molecular weight of poly(phenylacetylene)s was achieved). However, in the case of WOCl3(O-C6H3Cl2-2, 6) catalyst, it enhances the activity considerably by eliminating the induction period. Poly(phenylacetylene)s prepared with the catalysts studied have weight-average molecular weight ranging from 100 000 to 200 000. They are trans-prevailing and have relatively low molar fraction of monomer units comprised in cyclohexadiene sequences (about 6%).

Probing the molecular weights of sweetgum and pine kraft lignin fractions

TAPPI Journal ◽  
2021 ◽  
Vol 20 (6) ◽  
pp. 381-391
Author(s):  
JULIANA M. JARDIM ◽  
PETER W. HART ◽  
LUCIAN LUCIA ◽  
HASAN JAMEEL
Keyword(s):  
Molecular Weight ◽  
Black Liquor ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Systematic Investigation ◽  
Kraft Pulping ◽  
Molecular Weights ◽  
Lignin Recovery ◽  
Lignin Reactivity ◽  
Kinetics Of

The present investigation undertook a systematic investigation of the molecular weight (MW) of kraft lignins throughout the pulping process to establish a correlation between MW and lignin recovery at different extents of the kraft pulping process. The evaluation of MW is crucial for lignin characterization and utilization, since it is known to influence the kinetics of lignin reactivity and its resultant physicochemical properties. Sweetgum and pine lignins precipitated from black liquor at different pHs (9.5 and 2.5) and different extents of kraft pulping (30–150 min) were the subject of this effort. Gel permeation chromatography (GPC) was used to deter- mine the number average molecular weight (Mn), mass average molecular weight (Mw), and polydispersity of the lignin samples. It was shown that the MW of lignins from both feedstocks follow gel degradation theory; that is, at the onset of the kraft pulping process low molecular weightlignins were obtained, and as pulping progressed, the molecular weight peaked and subsequently decreased. An important finding was that acetobromination was shown to be a more effective derivatization technique for carbohydrates containing lignins than acetylation, the technique typically used for derivatization of lignin.

scholarly journals Characterisation of Sequential Solvent Fractionation and Base-catalysed Depolymerisation of Treated Alkali Lignin

BioResources ◽  
2015 ◽  
Vol 10 (3) ◽  
pp. 4137-4151 ◽  
Author(s):  
Aikfei Ang ◽  
Zaidon Ashaari ◽  
Edi Suhaimi Bakar ◽  
Nor Azowa Ibrahim
Keyword(s):  
Molecular Weight ◽  
Chemical Structure ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Solubility Parameters ◽  
Low Molecular Weight ◽  
Sequential Fractionation ◽  
Weight Average Molecular Weight ◽  
Solvent Fractionation ◽  
Alkali Lignin

An alkali lignin (OL) with a weight-average molecular weight (Mw) of 11646 g/mol was used to prepare low-molecular weight lignin for resin synthesis. The low-molecular weight lignin feedstock was obtained via base-catalysed depolymerisation (BCD) treatments at different combined severity factors. Sequential fractionation of the OL and BCD-treated lignins using organic solvents with different Hildebrand solubility parameters were used to alter the homogeneity of the OL. The yield and properties of OL itself and OL and BCD-treated OL dissolved in propan-1-ol (F1), ethanol (F2), and methanol (F3) were determined. Regardless of the treatment applied, a small amount of OL was dissolved in F1 and F2. The BCD treatment did not increase the yield of F1 but did increase the yields of F2 and F3. Gel permeation chromatography (GPC) showed that the repolymerization reaction occurred in F3 for all BCD-treated OL, so these lignins were not suitable for use as feedstocks for resin production. The GPC, 13Carbon-nuclear magnetic resonance, and Fourier transform infrared spectroscopy analyses confirmed that the F3 in OL exhibited the optimum yield, molecular weight distribution, and chemical structure suitable for use as feedstocks for resin synthesis.

Sign in / Sign up

Export Citation Format

Share Document