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Copolymerization Kinetics (copolymerization + kinetics)
Selected AbstractsAn Experimental Study on the Free-Radical Copolymerization Kinetics with Crosslinking of Styrene and Divinylbenzene in Supercritical Carbon DioxideMACROMOLECULAR REACTION ENGINEERING, Issue 1 2009Pedro R. García-Morán Abstract A study on the effect of process conditions and composition of the reacting mixture on the kinetics and particle properties in the copolymerization of styrene and divinylbenzene in supercritical carbon dioxide is presented. Polystyrene -block- polydimethylsiloxane and Krytox 257 FSL (Dupont) were used as stabilizers, and their performance compared. A 38 mL, high-pressure view cell, equipped with one frontal and two lateral sapphire windows, was used as the reacting vessel. The polymer product was characterized for total monomer conversion, gel content, molecular weight averages of the sol fraction and particle size distribution. Acceptable polymerization rates and partially-agglomerated spherical particles were produced under the conditions tested. [source] Microemulsion copolymerization of styrene and acrylonitrile with n -butanol as the cosurfactantJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2005Yuanchang Shi Abstract The microemulsion copolymerization of styrene and acrylonitrile in an n -butanol/cetyltrimethylammonium bromide/oil/water microemulsion system was studied. The solubilization sites of the two monomers were determined with an NMR technique. The results showed that the solubilization behaviors of the two monomers were quite different. Most of the styrene was solubilized in the palisade layer of the microemulsion, whereas the acrylonitrile had an equilibrium distribution in the aqueous phase and palisade layer of the microemulsion. The reactivity ratios of styrene and acrylonitrile in the microemulsion system were different from those in other media. The effect of the monomer feed composition on the copolymerization kinetics was investigated, and the mechanism of nucleation of the latex particles was examined. The experimental results showed that the copolymerization loci were changed from the microemulsion droplets to the aqueous phase when the concentration of acrylonitrile in the monomer feed reached approximately 80%; this could be further proved by the effect of the monomer feed composition on the copolymerization kinetics. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 203,216, 2005 [source] Copolymerization of Fluorinated Monomers with Hydrophilic Monomers in Aqueous Solution in Presence of CyclodextrinMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 11 2006Oliver Kretschmann Abstract Summary: New fluorinated copolymers were synthesized by copolymerization of 1H,1H,2H,2H- perfluorodecyl methacrylate (1) with hydrophilic comonomers methacrylic acid (3), 2-acrylamido-2-methylpropane sulfonic acid (6), 3-trimethylammonium propyl methacrylamide chloride (7) and N,N -dimethylmethacrylamidopropyl- N -3-sulfopropylammoniumbetaine (8). The reaction was carried out in water using randomly methylated , -cyclodextrin (RAMEB) for solubilization of the fluorinated monomer by forming a host-guest complex (1a). Polymerization kinetics were investigated and copolymerization parameters were determined. Additionally, a RAMEB complex of tert -butyl methacrylate (2a) was copolymerized with 1a in water. For comparison, copolymerization of the uncomplexed monomers 1 and 2 were carried out in organic solvents. Evaluation of copolymerization kinetics and parameters showed significant differences in the relative reactivities of the free monomers and the monomer-RAMEB complexes. [source] Modeling of the Nitroxide-Mediated Radical Copolymerization of Styrene and DivinylbenzeneMACROMOLECULAR REACTION ENGINEERING, Issue 5-6 2009Julio C. Hernández-Ortiz Abstract A mathematical model for the copolymerization kinetics with crosslinking of vinyl/divinyl monomers in the presence of nitroxide controllers has been developed and validated using experimental data of TEMPO-mediated copolymerization of styrene (STY) and divinylbenzene (DVB). Polymerization rate, molecular weight development, gelation point, evolution of sol and gel weight fractions, crosslink density, and copolymer composition, as well as concentrations of the species participating in the reaction mechanism can be calculated with the model. Diffusion-controlled effects were assessed and found unimportant. The presence of nitroxide controllers seems to favor the production of more homogeneous polymer networks, but this effect decreases as the initial fraction of crosslinker is increased. [source] On-line monitoring and fingerprint technology: new tools for the development of new catalysts and polyolefin materialsMACROMOLECULAR SYMPOSIA, Issue 1 2004Arno Tuchbreiter Abstract The High-Output Polymer Screening (HOPS) combines process-relevant automated reactor systems and rapid polymer characterization with on-line polymerization monitoring and automated data acquisition ("electronic notebook") in order to make effective use of advanced data mining tools. This has led to the development of fingerprint technology based upon correlations between spectroscopic data and polymerization process conditions, catalyst compositions, as well as polymer end-use properties. Infrared spectroscopic fingerprints proved to be very useful for accelerating polymer analyses including characterization of polymer molecular architectures as well as non-destructive testing of the mechanical, thermal and other end-use polymer properties. Such spectroscopic fingerprints represent important components of effective on-line quality control systems. With ATR-FT-IR probes on-line monitoring of catalytic olefin copolymerization was performed in solution to measure in real time copolymerization kinetics, catalyst productivities, catalyst deactivation as well as copolymerization parameters and copolymer sequence distributions. Monomer consumption and comonomer incorporation were monitored simultaneously. Advanced fingerprint technology can reduce significantly the need for time- and money consuming polymer testing and can also stimulate the search for new catalyst systems and polymeric materials. [source] Emulsion copolymerization of styrene and sodium styrene sulfonate: kinetics, monomer reactivity ratios and copolymer propertiesPOLYMER INTERNATIONAL, Issue 1 2009Dhamodaran Arunbabu Abstract BACKGROUND: The synthesis of poly[styrene- co -(sodium styrene sulfonate)], poly(S- co -NaSS), with a high loading of sulfonate groups is of current interest owing to its potential use in numerous areas. A series of these copolymers with various sulfonate loads were synthesized using the emulsion polymerization technique with a study of the copolymerization kinetics, monomer reactivity ratio and copolymer properties. RESULTS: The copolymerization kinetics are significantly enhanced with an increase of NaSS feed in the polymerization. Monomer reactivity ratios were determined from NMR data by employing the Fineman,Ross and Kelen,Tüdös methods. Styrene (r1) and NaSS (r2) reactivity ratios are 0.5 and 10, respectively. The colloidal particle size of the copolymers depends upon the NaSS composition. The thermal stability of the copolymers is greatly enhanced with higher NaSS content in the copolymer backbone. Higher glass transition temperatures are observed for the copolymers with higher NaSS content. CONCLUSION: The reactivity ratio values suggest that styrene prefers to form copolymers whereas NaSS produces homopolymers. It is also found that styrene copolymerization with NaSS is only twice as fast as homopolymerization. In contrast, NaSS homopolymerization is ten times faster than NaSS copolymerization with styrene. The NaSS content in the copolymer backbone affects the thermal stability and the glass transition of the copolymers. Copyright © 2008 Society of Chemical Industry [source] | ||||||||||