Bibliografías temáticas / Vinyl polymerization / Tesis

Tesis sobre el tema "Vinyl polymerization"

Siga este enlace para ver otros tipos de publicaciones sobre el tema: Vinyl polymerization.
Autor: Grafiati
Publicado: 18 de mayo de 2024

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros

Elija tipo de fuente:

Consulte los 50 mejores tesis para su investigación sobre el tema "Vinyl polymerization".

Junto a cada fuente en la lista de referencias hay un botón "Agregar a la bibliografía". Pulsa este botón, y generaremos automáticamente la referencia bibliográfica para la obra elegida en el estilo de cita que necesites: APA, MLA, Harvard, Vancouver, Chicago, etc.

También puede descargar el texto completo de la publicación académica en formato pdf y leer en línea su resumen siempre que esté disponible en los metadatos.

Explore tesis sobre una amplia variedad de disciplinas y organice su bibliografía correctamente.

1

Dorobantu, Ioana-Miruna. "Vinyl chloride polymerization in microdroplet reactor". Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0037/document.

Texto completo
Resumen
La polymérisation du chlorure de vinyle est une réaction très fréquente dans l’industrie des polymères, conduisant à l’obtention d’un matériau plastique très commun, connu sous le nom de PVC (polychlorure de vinyle). Ses applications concernent principalement l’industrie des constructions néanmoins d’autres domaines sont également touchés. La complexité de ce procédé de polymérisation est due à la nature toxique du monomère, à la maitrise du transfert de chaleur ou au maintien de l’agitation. Le control de ces variables de procédé influence de manière directe les caractéristiques finales du produit. Même si la polymérisation en suspension du chlorure de vinyle a été largement étudiée dans des réacteurs de type batch, il y a un manque de données au niveau de la cinétique et de la physicochimie d’une goutte de monomère pendant la réaction. L’objectif de ces travaux est de proposer un dispositif microstructuré permettant d’obtenir des gouttes monodisperses ayant un diamètre de 200 µm environ, chacune étant considérée comme un réacteur de polymérisation. Une fois identifiés les verrous liés au système eau/chlorure de vinyle en microréacteur, la réaction de polymérisation a été décrite de manière qualitative par visualisation des gouttes/grains de polymère. Des mesures Raman non-invasives en temps réel ont été réalisées sur une goutte immobile de chlorure de vinyle, cela permettant d’accéder aux valeurs des constantes cinétiques. Un modèle théorique en bon accord avec les résultats expérimentaux a été proposé afin de simuler le degré de conversion de la réaction. Les caractéristiques morphologiques des grains de PVC obtenus en microréacteur présentent des particularités intéressantes en termes d’agglomération des particules primaires ou porosité
Vinyl chloride suspension polymerization is a common reaction in polymer industry allowing to obtain one of the world wide most used plastics, known as PVC (polyvinyl chloride). Its applications involve mostly the construction industry but other domains are also concerned. This polymerization process is highly complex due to the toxic nature of the monomer, the good manage of heat transfer and agitation. The control of these process variables directly impacts the characteristics of the final product. Even though the suspension polymerization of vinyl chloride has been extensively studied in batch reactors, there is a lack of data regarding the kinetics or the physicochemistry of a single monomer droplet during the reactions. The aim of this present work is to propose a microstructured device which enables obtaining monodisperse droplets within 200 µm in diameter, each one being considered as a polymerization reactor. After a good acknowledgement of the vinyl chloride/water system in microchannel the polymerization reaction was qualitatively described by means of droplet/polymer grain visualization. Real-time non-invasive Raman measurement has been performed on stationary vinyl chloride monomer droplets and has provided values of kinetic constants. A theoretical model was proposed, simulating the reaction conversion in good agreement with the experimental values. The morphologic characteristics of the PVC grains obtained in microreactor presented interesting features in terms of primary particle agglomeration or porosity
Los estilos APA, Harvard, Vancouver, ISO, etc.
2

De, Bruyn Hank. "The Emulsion Polymerization of Vinyl Acetate". Thesis, The University of Sydney, 1999. http://hdl.handle.net/2123/381.

Texto completo
Resumen
Abstract This work investigates the kinetics of the emulsion polymerization of vinyl acetate. Several aspects of this system have been clarified, including the induced decomposition of persulfate, retardation by oxygen and entry by, and analysis of, the aqueous phase oligomeric radicals. It has been shown that the retardation period observed in the emulsion polymerization of VAc can be explained by the effect of traces of oxygen (< 10-6 M) on the entry efficiency of the initiator-derived aqueous-phase oligomeric radicals. Comparison of rates of polymerization in V and persulfate -initiated polymerizations together with electrospray mass spectrometry of aqueous phase oligomers, has shown that the mechanism for the induced decomposition of persulfate by vinyl acetate is chain transfer to initiator from aqueous-phase oligomeric radicals. A value has been determined for the rate coefficient for transfer to initiator, by fitting literature data to a model based on this mechanism. The reported independence of the rate of polymerization from the monomer concentration in the emulsion polymerization of vinyl acetate has been investigated. Possible explanations for this behaviour have been proposed and tested in this work, by measuring radical-loss rates directly with y-relaxation techniques. Although the Y relaxations were found to be affected by experimental artefacts, it has been demonstrated that rapid exit is not responsible for the high radical-loss rates in this system. The major artefact identified in the y relaxations was the significant effect of relatively small exotherms on relaxation behaviour, Methodologies were developed for correcting affected data and for avoiding exotherms under certain conditions. Arrhenius parameters were determined for the rate coefficient for chain transfer to monomer using the In^M method, which utilises the whole MWD. This section of the work is incomplete, for reasons detailed in chapter 5. However, as a preliminary indication it was found that the frequency factor was 106.38 M-1 s-1 and the activation energy was 38.8 kJ mol-1.
Los estilos APA, Harvard, Vancouver, ISO, etc.
3

De, Bruyn Hank. "The Emulsion Polymerization of Vinyl Acetate". University of Sydney, Chemistry, 1999. http://hdl.handle.net/2123/381.

Texto completo
Resumen
Abstract This work investigates the kinetics of the emulsion polymerization of vinyl acetate. Several aspects of this system have been clarified, including the induced decomposition of persulfate, retardation by oxygen and entry by, and analysis of, the aqueous phase oligomeric radicals. It has been shown that the retardation period observed in the emulsion polymerization of VAc can be explained by the effect of traces of oxygen (< 10-6 M) on the entry efficiency of the initiator-derived aqueous-phase oligomeric radicals. Comparison of rates of polymerization in V and persulfate -initiated polymerizations together with electrospray mass spectrometry of aqueous phase oligomers, has shown that the mechanism for the induced decomposition of persulfate by vinyl acetate is chain transfer to initiator from aqueous-phase oligomeric radicals. A value has been determined for the rate coefficient for transfer to initiator, by fitting literature data to a model based on this mechanism. The reported independence of the rate of polymerization from the monomer concentration in the emulsion polymerization of vinyl acetate has been investigated. Possible explanations for this behaviour have been proposed and tested in this work, by measuring radical-loss rates directly with y-relaxation techniques. Although the Y relaxations were found to be affected by experimental artefacts, it has been demonstrated that rapid exit is not responsible for the high radical-loss rates in this system. The major artefact identified in the y relaxations was the significant effect of relatively small exotherms on relaxation behaviour, Methodologies were developed for correcting affected data and for avoiding exotherms under certain conditions. Arrhenius parameters were determined for the rate coefficient for chain transfer to monomer using the In^M method, which utilises the whole MWD. This section of the work is incomplete, for reasons detailed in chapter 5. However, as a preliminary indication it was found that the frequency factor was 106.38 M-1 s-1 and the activation energy was 38.8 kJ mol-1.
Los estilos APA, Harvard, Vancouver, ISO, etc.
4

Vale, Hugo. "Population Balance Modeling of Emulsion Polymerization Reactors : applications to Vinyl Chloride Polymerization". Lyon 1, 2007. http://www.theses.fr/2007LYO10034.

Texto completo
Resumen
This thesis is a contribution to the development of population balance models of emulsion polymerization and, more particularly, to the modeling of particle formation and particle size distribution (PSD) in vinyl chloride emulsion polymerization. The rst part of the work is dedicated to the acquisition of experimental data. Ab initio polymerizations were done to obtain reliable data regarding the dependence of the particle number on the concentration of surfactant, as well as to analyze the effect of the initiator concentration, stirring rate, and monomer-to-water ratio upon the particle number and the polymerization kinetics. In addition, seeded polymerizations were carried out at different concentrations of seed latex and emulsifier in order to quantify the influence of these factors on the onset and extent of secondary particle formation. Moreover, the adsorption isotherms of SDS and SDBS on poly (vinyl chloride) latex particles were determined. The second part of the manuscript focuses on the development of the population balance model. A special feature of the model proposed in this work is the computation of the coupled radical number and particle size distributions by the zero-one-two population balance equations. Overall, the examples presented show that the model can capture the tendencies observed in the polymerizations with physically reasonable values of the unknown/ adjustable parameters. With respect to particle formation, it was seen that including the possibility of particle nucleation (homogeneous and micellar) by exited radicals helps to explain the high particle numbers observed and the fact that the initiator concentration has a negligible effect on the particle number. Moreover, it was demonstrated that particle coagulation must be taken into account in order to obtain plausible PSDs and to avoid the use of abnormally low values of the efficiency of radical entry into micelles. In the third and last part, two novel numerical methods for the solution of population balances of interest to emulsion polymerization systems are presented and discussed
Cette thèse est une contribution au développement de modèles mécanistiques de la polymérisation en émulsion et, plus particulièrement, une contribution à la modélisation de la formation des particules et de leur distribution de taille (DTP) lors de la polymérisation en émulsion du chlorure de vinyle. La première partie de l'étude est consacrée à l'obtention de données expérimentales. Des polymérisations ab initio ont été réalisées afin d'obtenir des données fiables sur l'effet de la concentration de tensioactif, concentration d'initiateur, vitesse d'agitation et rapport monomère/eau sur le nombre de particules formées et sur la cinétique de polymérisation. Des polymérisations ensemencées ont également été réalisées afin de déterminer l'influence de la quantité de semence et de la concentration de tensioactif sur la formation de particules par nucléation secondaire. Enfin, les isothermes d'adsorption du SDS et du SDBS sur des particules de latex de poly (chlorure de vinyle) ont été déterminées. La deuxième partie de l'étude concerne le développement et la validation du modèle de polymérisation. Celui-ci à la particularité d'utiliser les bilans de population propres aux systèmes ‘zéro-un-deux' pour déterminer la distribution jointe du nombre de radicaux et de la taille des particules. Dans l'ensemble, les résultats obtenus montrent que le modèle proposé est capable de décrire les principaux comportements retrouvés lors des polymérisations avec des valeurs physiquement plausibles des paramètres inconnus ou ajustables. Pour ce qui concerne la formation des particules, il s'avère que la prise en compte de la possibilité de nucléation (homogène ou micellaire) par les radicaux désorbés aide à expliquer les valeurs élevées du nombre de particules ainsi que l'effet négligeable de la concentration d'initiateur sur le nombre de particules. En autre, il est démontré que le phénomène d'agrégation des particules doit être pris en considération afin d'obtenir des DTPs cohérentes. Dans la troisième et dernière partie, deux nouvelles méthodes numériques pour la résolution de bilans de population d'intérêt pour la modélisation des systèmes de polymérisation en émulsion sont proposées et analysées
Los estilos APA, Harvard, Vancouver, ISO, etc.
5

Morin, Aurélie. "Controlled radical polymerization of vinyl esters and vinyl amides : experimental and theoretical studies". Thesis, Toulouse, INPT, 2013. http://www.theses.fr/2013INPT0117/document.

Texto completo
Resumen
Ces travaux de thèse portent sur la polymérisation radicalaire contrôlée (PRC) des esters et amides de vinyle. L’une des possibilités de contrôle est le piégeage dynamique réversible des chaînes radicalaires croissantes (P•) par un agent de contrôle (T) formant une espèce dormante (P─T’). La concentration en radicaux dans le milieu peut alors diminuer dramatiquement de sorte que les réactions indésirables de terminaisons soient négligeables et que le contrôle de la masse molaire des polymères soit atteint avec un faible indice de dispersité. L’utilisation de complexes métalliques, pouvant s’oxider et former une liaison métal-carbone, comme agent de piégeage des radicaux est une manière de réaliser ce contrôle. La PRC est alors appelée Polymérisation Radicalaire Contrôlée par voie Organométallique (OMRP). A ce jour, plusieurs métaux de transitions ont été utilisés avec plus ou moins de succès en OMRP. Lors de cette étude, nous avons synthétisé des complexes de cuivre(I) et testé leurs performances pour l’OMRP de l’acétate de vinyle et de l’éthylène. Nous avons également utilisé des outils de chimie théorique pour mieux comprendre pourquoi le cobalt(II) acétylacétonate est, jusqu’à aujourd’hui, le meilleur agent de contrôle pour la polymérisation de l’acétate de vinyle et des amides de vinyle. Grâce à la théorie de la fonctionnelle de densité (DFT), nous avons mis en lumière le rôle crucial de la coordination sur le cobalt des groupements carbonyles des monomères étudiés
This thesis focus on Controlled Radical Polymerization (CRP) of vinyl esters and vinyl amides. One of the possibilities to achieve this control is a dynamic reversible trapping of the growing radical chains (P•) by a controlling agent (T) to form a dormant species (P─T’). The radical concentration in the medium can be dramatically reduced so that the unwanted terminations are disfavored and polymers with controlled molecular weights and low dispersity can be obtained. A way to achieve this control is the use of metallic complexes, which can oxidize and form a metal-carbon bond, as trapping agent in the so-called Organometallic Mediated Radical Polymerization (OMRP). So far, different transition metals have been used with gretaer or smaller success. In this study, the synthesis of copper(I) complexes and their investigation for the vinyl acetate and ethylene polymerization under OMRP conditions were performed. We also used computational chemistry as a tool to better understand why the cobalt(II) acetylacetonate (Co(acac)2) has, so far, given the best results for either vinyl acetate or vinyl amides polymerization. Thanks to Density Functional Theory (DFT), the crucial role of the monomer carbonyl group coordination to cobalt was pointed out
Los estilos APA, Harvard, Vancouver, ISO, etc.
6

Altinsoy, Sule. "Polymerization And Characterization Of N-vinyl-2-pyrrolidone". Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611238/index.pdf.

Texto completo
Resumen
N-vinyl-2-pyrrolidone, NVP, was polymerized by &
#56256
&
#56394
-radiation in the presence of atmospheric oxygen and under vacuum at different periods. Polymerization also conducted by using chemical initiator, &
#56256
&
#56466
-Azoisobutyronitrile, AIBN, in bulk at different temperatures and times. The activation energy for polymerization was found from Arrhenius plot as 31,8 kJ/mol. By using the Fox-Flory equation T&
#56256
&
#56394
and k values calculated for each polymerization methods. The polymer obtained was white gel type. The different types of polymer obtained were investigated by FT-IR, 1H-NMR and 13C-NMR, DSC, TGA and viscosity measurement methods. According to the FT-IR and NMR results, the polymerizations proceeded via vinyl group. As expected, solution viscosity measurements and DSC results showed that the glass transition temperature of polymer increases with increasing molecular weight.
Los estilos APA, Harvard, Vancouver, ISO, etc.
7

Mishima, Eri. "Organoheteroatom-Mediated Living Vinyl Polymerization under Acidic Condition". 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157613.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
8

Scholten, Marc Davis. "Strategies for the controlled polymerization of vinyl monomers /". May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
9

Cho, Chang Gi. "Controlled polymerization of alkyl vinyl ethers via 'covalent' propagating species". Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/53930.

Texto completo
Resumen
The study of the polymerization of alkyl vinyl ethers initiated by HI/I₂ catalyst is directed into two areas: the kinetics of the polymerization and the strategy of amine functionalized prepolymer synthesis. The polymerization reactions show living behavior in nonpolar solvents at low temperatures. The observed rate of polymerization under reaction conditions is linearly dependent on the initial concentration of hydrogen iodide and iodine, respectively. However, the monomer concentration does not influence the rate of polymerization(apparent zero-order). Two possible reaction schemes are proposed from the observed rate equation and attempts are made to distinguish them by using UV/visible spectroscopy and carbon-13 NMR spectroscopy. In both schemes a reversible interaction between a monomer and an iodine molecule is postulated as a necessary elemental reaction to fit the observed expression for the rate of polymerization. From spectroscopic analysis results, the interaction between the iodide compound(chain end) and the iodine molecule seems to be very weak compared to the interaction between the monomer and the iodine molecule. A synthetic strategy for amine functionalized prepolymer synthesis has been developed via a series of model reactions. Incorporation of a styrenic monomer at the propagating chain end of living poly(alkyl vinyl ethers) provides a convenient intermediate synthesis of a relatively stable amine functionalized prepolymer. Proper selection of substituents at the styrenic monomer optimizes the cross addition reaction and amination reactions. Linear alkylamines with lower carbon numbers are used in the amination reaction in order to promote the nucleophilic substitution reaction and to minimize possible elimination reactions. A series of amine functionalized oligomers are synthesized by employing the synthetic strategy in combination with the previous kinetic result of the homopolymerization. For oligomers, incorporation of a few units of ethyl vinyl ethers at the chain end facilitates the cross addition reaction. Synthesized amines are characterized by various spectroscopic methods. Then, titrated molecular weights show good agreement with their theoretical molecular weights in several cases.
Ph. D.
Los estilos APA, Harvard, Vancouver, ISO, etc.
10

Holt, J. M. "Studies on the formation of water soluble vinyl polymers". Thesis, University of Huddersfield, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378968.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
11

Bhattacharya, Jagannath. "Physico-chemical studies on selected aspects of clay catalyzed vinyl polymerization". Thesis, University of North Bengal, 1988. http://hdl.handle.net/123456789/717.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
12

Lobry, Emeline. "Batch to continuous vinyl chloride suspension polymerization process : a feasibility study". Phd thesis, Toulouse, INPT, 2012. http://oatao.univ-toulouse.fr/11498/1/lobry.pdf.

Texto completo
Resumen
Continuous processes present the benefit to be safer and more cost saving than batch processes. Many researches have been carried out in fine chemistry but few contributions refer to polymerization. We focus on the vinyl chloride suspension polymerization. This process has been extensively studied in batch with lots of improvement regarding the formulation and the technologies. This polymerization process is highly complex due to the toxic nature of the monomer, the good manage of heat transfer and stirring. Moreover the reaction step remains the only batch step of the PVC production. According to the PVC grain formation, the process can be divided into three steps (i) a liquid-liquid dispersion step in which the monomer droplet (30-50 µm) are generated and stabilized, (ii) a controlled agglomeration step of the reacting droplets exhibiting a sticky behaviour, (iii) a reaction step until the conversion rate is around 80-90% and the particles size is stable. In this study, the different technologies suitable for the different steps are pointed out. Based on the state of the art of the grain behaviour depending on the reaction conversion and on the literature concerning polymerization continuous process, static mixers and different co-current pulsed columns are proposed. Three technologies with different model system were chosen to study the liquid-liquid dispersion step. Static mixers allow the control of the droplet size under turbulent flow. In the range of the operating conditions, the dispersed phase concentration does not have a significant effect on the droplet size. The interfacial tension appears to be the most significant physico-chemical parameters. Correlation to predict the mean droplet size is proposed depending on different dimensionless numbers based on the hydrodynamics and on the systems: the Reynolds and Weber numbers. Given the promising results, static mixers are implemented at pilot scale to load the batch prior to polymerization. Their use demonstrates a noticeable reduction of the loading time and a better homogenisation of the different suspending agents and initiator inside the PVC grain. The two co-current pulsed columns design studied are the discs and doughnuts pulsed column and the COBR (continuous oscillatory baffled reactor, Nitech). For the first one, the effect of the packing materials (type and height), of the physico-chemical parameters (dispersed phase concentration, surfactant) and of hydrodynamic parameters (flowrate and oscillation conditions) on the droplet size are investigated where as for the second one the study is limited to the hydrodynamic parameters. A mean droplet size correlation is proposed based on the characteristic dimensionless numbers. The three continuous contactors used for liquid-liquid dispersion are compared in term of energy dissipation rate. The reaction is carried out in a continuous tubular reactor (the pulsed column). The column is suitable to transport solid-liquid suspension. Vinyl acetate suspension polymerization is performed to demonstrate the feasibility and particularly to study the encrusting and fouling problem. The first results are very promising.
Los estilos APA, Harvard, Vancouver, ISO, etc.
13

Rajesh, Kumar K. "Studies in polymerization of vinyl monomers using homogeneous transition metal catalysts". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1999. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2917.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
14

Lange, Hanna. "Emulsion polymerization of vinyl acetate with renewable raw materials as protective colloids". Thesis, KTH, Skolan för kemivetenskap (CHE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-41019.

Texto completo
Resumen
Emulsion polymerizations of vinyl acetate (VAc) were performed by fully or partially replacing poly(vinyl alcohol) (PVA) with renewable materials as protective colloids or by adding renewable materials, as additives or fillers, to the emulsions during or after polymerization. The purpose of the study was to increase the amount of renewable materials in the emulsion. A total of 19 emulsions were synthesized. Different recipes were used for the synthesis. The following renewable materials were studied; hydroxyethyl cellulose (HEC) with different molecular weights, starch and proteins. HEC and starch were used as protective colloids. Proteins were used as additives or fillers. Cross-linking agent A and Cross-linking agent B were used as cross-linking agents. A total of 26 formulations were pressed, either cold or hot. The synthesized emulsions were evaluated with respect to pH, solids content, viscosity, minimum film formation temperature (MFFT), glass transition temperature (Tg), particle size and molecular weight (Mw). The tensile shear strengths of the emulsions were evaluated according to EN 204 and WATT 91. It was possible to fully, or partially, replace PVA as protective colloid with renewable materials. It was also possible to use renewable materials as additives or fillers in the emulsions. The emulsions obtained properties that differed from the reference. Generally, emulsions with HEC as protective colloid showed lower viscosity and slightly higher MFFT, Tg and molecular weight than emulsions with PVA as protective colloid. Larger particle sizes than the reference were obtained for emulsions containing PVA combined with renewable materials. The emulsion with starch as protective colloid exhibited the largest particle size. 10 formulations passed the criteria for D2. The emulsions where PVA was fully or partially replaced with HEC or starch showed a water resistance similar to the reference (around D2). The addition of protein did not decrease the water and heat resistance compared to the reference. Addition of protein after polymerization increased the water resistance (D2) compared to addition during polymerization. Addition of cross-linking agents did not increase the water resistance further. Two formulations passed the criteria for D3. The emulsion in the first formulation had PVA as protective colloid and protein B was added during polymerization. The emulsion in the second formulation had HEC as protective colloid. To both of these emulsions, protein A was added after polymerization, as a filler, combined with Cross-linking agent B as cross-linking agent before hot pressing. The first formulation also showed a good heat resistance (passed the criteria for WATT 91).
Los estilos APA, Harvard, Vancouver, ISO, etc.
15

Horrill, M. D. "The effect of suspending agents on the suspension polymerization of vinyl chloride". Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/7513.

Texto completo
Resumen
The suspension polymerisation of vinyl chloride is the main industrial process used for the manufacture of PVC. The aim of this project was to study the suspension polymerisation of vinyl chloride monomer to form PVC. The work concentrated on the effects that the choice of suspension stabilisers (PVA's), pH and other environmental factors had on the properties of both the initial droplet suspension and the polymerising system throughout the course of the reaction. Experiments were carried out using a pressurised 11 stainless steel jacketed reactor connected to an external optical cell. Progress of the polymerisation was monitored optically by taking samples into the cell at regular intervals and examining them with a microscope which had an attached camera. Properties that were studied included the drop size and drop size distribution of the initial droplet suspension, the stabiliser take-up during the reaction and the particle size distribution, porosity and physical appearance of the polymer particles. The work showed that the choice of suspension stabiliser not only effected the drop size and drop size distribution of the initial suspension but also effected the properties and particle size of the final polymer product which was produced. The pH of the system was also discovered to effect both drop stability and the course of the polymerisation. Lowering the pH (pH 10) had a drastic effect. At high pH, the droplet suspension that was formed was highly unstable and the polymer product that was formed consisted of very large, coarse grains. Other environmental factors (reactor heat up rate, oxygen concentration, the location of secondary PVA (aqueous or organic phase), delaying the addition of the primary PVA and simultaneous charging of both phases to the reactor) were also discovered to effect the properties of both the droplet suspension and the polymer product although the suspension was found to be more resilient to changes in the operating conditions than the polymer.
Los estilos APA, Harvard, Vancouver, ISO, etc.
16

Pound, Gwenaelle. "Reversible addition fragmentation chain transfer (RAFT) mediated polymerization of N-vinylpyrrolidone". Thesis, Link to the online version, 2008. http://hdl.handle.net/10019/892.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
17

Bronk, John M. "Synthesis and characterization of poly (butyl vinyl ether) homopolymers and copolymers utilizing the aluminum hydrogen sulfate catalyst system". Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-08182009-040347/.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
18

Si, Kun. "Kinetics and Mechanism of Vinyl Chloride Polymerization: Effects of Additives on Polymerization Rate, Molecular Weight and Defect Concentration in the Polymer". online version, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1168382967.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
19

Mochizuki, Shuto. "Controlled radical polymerization in designed porous materials". Kyoto University, 2019. http://hdl.handle.net/2433/242535.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
20

Cummings, Shidan. "The Incorporation of Vinyl Modified Regenerated Starch Nanoparticles in Emulsion Polymerizations". Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36094.

Texto completo
Resumen
The replacement of synthetic polymers with renewable content in emulsion polymerization latexes has been a focus of research over the past several decades. Emulsion polymerization is a more sustainable way to produce polymers for films and resins. Starch is a sustainably sourced material that has proven to be extremely useful as a filler, comonomer, and property modifier for polymer latexes. In this thesis, we attempt to incorporate high levels of starch materials into emulsion latex using waxy and dent sourced (cheaper) vinyl-functionalized regenerated starch nanoparticles (RSNPs). When fed as a batch charge, incorporation (by reaction as opposed to blending) of a grade of waxy RSNPs with 3 wt.% polymerizable sugar-based monomer (PSBM) and medium hydrophobicity (S-3-M) into the polymer matrix was 0-10 wt.% for a 15 wt.% RSNP loaded, 40 wt.% solids latex. Semi-batch feeding of the S-3-M RSNPs resulted in stable latex with the highest loadings of 40 and 50 wt.% (40 wt.% solids) with 0-10 wt.% RSNP incorporation into the synthetic particles, while 40 wt.% loading (20 wt.% incorporation) was achieved with a grade of waxy RSNPs with 6 wt.% PSBM and medium hydrophobicity (S-6-M). Strategies were developed to prepare synthetic latexes with high RSNP loadings and moderate incorporation. Dent sourced RSNPs proved difficult to use in emulsion formulations due in part to the higher percentage of water-soluble linear amylose in the nanoparticles. To reduce the chances of coagulation and minimize the viscosity of the final latex it was important to ensure monomer starved conditions, that the only initiator feed occurred at the seed stage of the reaction (to degrade the soluble starch and prevent later stage coagulation), and that a hydrophobic tie-layer was used to assist in removal of soluble starch from the water phase. Although a successful procedure was devised for creating a dent sourced RSNP loaded latex with a viscosity of 250 cp, it was significantly longer than the procedures used with waxy RSNPs (6 h polymerization + 1 h RSNP dispersion). An additional treatment of the RSNP dispersion prior to the polymerization can lower the final latex viscosity to 100 cp. Higher incorporation of vinyl-functionalized RSNPs may be achievable if the covalently bonded PSBM functional groups are resistant to hydrolysis, the amylose and other small MW starches are completely removed from the water phase, and monomers with more appropriate reactivity and hydrophobicity are employed. To this end, maleic and methacrylic anhydride modified RSNPs were prepared and tested in emulsion polymerizations. The maleic anhydride modified RSNPs were successfully loaded into an emulsion latex at 15 wt.% (40 wt.% solids content) resulting in 20-30 wt.% incorporation when utilizing 2-ethylhexyl acrylate as the tie-layer monomer with 2-ethylhexyl acrylate or butyl acrylate/methyl methacrylate/acrylic acid as the shell layer. This work presents the only comprehensive attempt to incorporate RSNPs into synthetic latexes at high loadings and solids with persulfate initiation without the need to severely reduce the RSNP molecular weight. The learning generated provides a framework for continuing research into increasing the incorporation of RSNPs into polymer particles.
Los estilos APA, Harvard, Vancouver, ISO, etc.
21

Al-Aeeb, Ahmed. "The synthesis of 1-butene oligomers with vinyl endgroups and their use in further reactions". Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/379.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
22

Hedir, Guillaume. "Functional degradable polymers via RAFT/MADIX mediated polymerization of cyclic ketene acetals and vinyl monomers". Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/81939/.

Texto completo
Resumen
This thesis explores the synthesis of functional degradable polymers via the radical ringopening polymerization (rROP) of cyclic ketene acetal (CKA) monomers and their copolymerization with vinyl ester monomers using the reversible addition-fragmentation chain transfer (RAFT/MADIX) polymerization. Chapter 1 introduces the polymerization technique used in this thesis (namely RAFT polymerization) and gives a summary of the conventional and new approaches to synthesize poly(esters) for use as degradable materials, with a focus on the arising use of rROP of CKA monomers. In Chapter 2 the copolymerization of the CKA 2-methylene-1,3-dioxepane (MDO) and vinyl acetate (VAc) is investigated using RAFT/MADIX polymerization with a view towards the formation of degradable copolymers with controlled molecular weights and narrow dispersities. Chapter 3 discusses the use of the palladium vinyl exchange reaction to create a novel functional bromine derivative monomer of VAc, vinyl bromobutanoate (VBr). The homopolymerization of VBr and copolymerization with MDO using the RAFT/MADIX polymerization is further reported to produce homopolymers and degradable copolymers with functional pendent groups able to be further modified post-polymerization to introduce different properties to the polymer materials. In Chapter 4 further investigation into the RAFT/MADIX copolymerization of VAc and MDO, as well as its homopolymerization, is explored using a different chain transfer agent (CTA) in order to understand the cause of the lower degree of control observed for some of the copolymerizations in Chapter 2. Chapter 5 describes the formation of degradable hydrophilic copolymers showing tunable thermoresponsive properties via the copolymerization of MDO and novel oligo(ethyleneglycol) methyl ether vinyl acetate monomers. In Chapter 6 the copolymerization of MDO with vinyl ester monomers is presented using a macro-CTA of poly(N-vinylpyrrolidone) to create amphiphilic block copolymers of poly(NVP)-b-poly(MDO-co-vinyl esters) able to self-assemble in water to form degradable nanoparticles. Chapter 7 provides a summary of the work reported in Chapters 2-6 and potential perspectives for the methodology designed in this thesis.
Los estilos APA, Harvard, Vancouver, ISO, etc.
23

Kingsley, Kyle. "Features of Highly Hydrophobic Plant Oil-Based Vinyl Monomers in Cationic and Free Radical Polymerization". Diss., North Dakota State University, 2019. https://hdl.handle.net/10365/29456.

Texto completo
Resumen
The demand for polymeric materials, which have traditionally been produced from petroleum-based resources over the last century, continues to grow each year. However, the supply of fossil fuels is limited. This, along with price volatility, harmful effects on the environment, and stricter regulations, have led to a surge in the exploration of suitable replacements, namely renewable resources such as plant and vegetable oils. In this work, newly synthesized highly hydrophobic plant oil-based vinyl monomers were polymerized using different mechanisms and processes to obtain polymer coatings and crosslinked films. First, novel vinyl ether monomers derived from soybean oil were copolymerized with vinyl ether counterparts derived from poly(ethylene glycol) (PEG) via cationic polymerization to prepare alkyd-type coatings. Soybean oil-derived polymer coatings and free films were formed by autoxidation of the unsaturation provided by the parent soybean oil moieties. Studies revealed that mechanical and viscoelastic properties, hydrophobicity, and morphology of coatings were dependent on copolymer composition and even more strongly on molecular weight and molecular weight distribution. The soybean oil-derived polymer coatings exhibited Tg values below room temperature, and it was shown that their thermomechanical properties were dependent on crosslink density. Next, plant oil-based acrylic monomers (POBMs) from soybean, high oleic soybean, and olive oils were copolymerized with styrene, methyl (meth)acrylate, and vinyl acetate to yield latexes and prepare polymer films with tailorable thermomechanical properties. Feasibility of the emulsion process was realized with regard to parent plant oil structure (unsaturation amount), POBM content and comonomer aqueous solubility, by determining copolymerization kinetics, mode(s) of latex particle nucleation, and molecular weight of resulting latex copolymers. POBM-emulsifier interactions, competing modes of latex particle nucleation, and effect of comonomer radical reactivity have all been investigated. Total monomer conversion and molecular weight of latex copolymers were enhanced by incorporation of an amphiphilic oligosaccharide (methyl-β-cyclodextrin) within the reaction system, which increases the availability of the POBMs and simultaneously diminishes degradative chain transfer reactions that are triggered by POBM fatty acid unsaturation fragments.
National Science Foundation (NSF)
ND EPSCoR
Los estilos APA, Harvard, Vancouver, ISO, etc.
24

Garcia, Guillermina C. "Synthesis of Hyperbranched Polyacrylates Using Self-Condensing Vinyl Polymerization (SCVP) Atom Transfer Radical Polymerization (ATRP) by Diverse Initiation Techniques in Aqueous Dispersed Systems". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1385200361.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
25

Ohgi, Hiroyuki. "Studies on Synthesis and Physical Properties of Highly Isotactic Poly(vinyl alcohol) Derived from Poly(tert-butyl vinyl ether)". 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/57290.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
26

Iwahara, Kenji. "Free radical polymerization of aromatic and vinyl compounds by manganese peroxidase of the basidiomycete,Bjerkandera adusta". Kyoto University, 2001. http://hdl.handle.net/2433/78120.

Texto completo
Resumen
Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第8992号
農博第1174号
新制||農||820(附属図書館)
学位論文||H13||N3511(農学部図書室)
UT51-2001-F322
京都大学大学院農学研究科林産工学専攻
(主査)教授 桒原 正章, 教授 酒井 富久美, 教授 島田 幹夫
学位規則第4条第1項該当
Los estilos APA, Harvard, Vancouver, ISO, etc.
27

Shaaban, Ahmad Mohammad Ragab. "Synthesis and characterization of fluorinated linear and (hyper)branched (co)polymers via self-condensing vinyl polymerization (SCVP) in minimeulsion". University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1561745661188082.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
28

Erdem, Yelda. "Hydrogel From Template Polymerization Of Methacrylic Acid And N-vinylpyrollidone And Polyethyleneoxide". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606024/index.pdf.

Texto completo
Resumen
ABSTRACT HYDROGEL FROM TEMPLATE POLYMERIZATION OF METHACRYLIC ACID AND N-VINYLPYRROLIDONE AND POLYETHYLENEOXIDE Yelda, Erdem Department of Polymer Science and Technology Supervisor : Prof. Dr. Teoman Tinç
er April 2005, 53 pages This theses covers the preparation and the characterization of a rigid hydrogel from N-Vinyl pyrrolidone-methacrylic acid (VP-MAA) monomers and polyethyleneoxide (PEO) polymer. Hydrogels are hydrophillic natured three dimensional networks which can swell in the presence of water. The VP-MAA-PEO hydrogel was obtained by template polymerization which can be defined as a method of polymer synthesis in which specific interactions consists of the preparation of a polymer (daughter polymer) in the presence of a macromolecular compound (template polymer). The hydrogel of VP-MAA-PEO was synthesized by using azobisisobutyronitrile (AIBN) as the initiator, tetrahydrofurane (THF) as the solvent and the temperature of the system was kept constant at 50º
C. Two kinds of VP-MAA-PEO hydrogels were prepared. The only difference between them were their solubilities in water. This difference is due to different crosslinking agent weight percentages of ethylene glycol dimethacrylic (EGDMA) to make the hydrogel water insoluble. The comparison of two hydrogels were carried by swelling behaviors at different pH values and different temperatures. Thermal stability of these two hydrogels were also examined by differential scanning calorimetry (DSC), spectroscopic properties were compared by using FTIR spectrometer and morphological studies were analyzed by using scanning electron microscope (SEM).
Los estilos APA, Harvard, Vancouver, ISO, etc.
29

Schmalen, Angela [Verfasser]. "Post polymerization modification of poly(vinyl amine) with functional epoxides : multifunctional, antimicrobial, protein-like polymers / Angela Schmalen". Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2015. http://d-nb.info/1066984344/34.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
30

Lehman, Stephen E. "Ruthenium catalysis in metathesis polymerization synthesis of linear copolymers of ethylene and polar vinyl monomers via metathesis /". [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001021.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
31

Östman, Anders. "RAFT-Polymerization of N-Vinyl Pyrrolidone and MethylMethacrylate for Synthesis of Functional Co-BlockpolymerBinders for Solid Electrolyte Batteries". Thesis, Uppsala universitet, Institutionen för kemi - Ångström, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-265498.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
32

Baena, Johanna. "PROCESSING AND KINETIC STUDIES OF THE REACTIVE BLENDS OF POLY(VINYL CHLORIDE) AND THERMOPLASTIC POLYURETHANES". University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1163727625.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
33

Königsmann, Martin. "Modification of Wood Surfaces via controlled Polymerization Methods". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E4BA-1.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
34

Lizotte, Jeremy Richard. "Synthesis and Characterization of Tailored Macromolecules via Stable Free Radical Polymerization Methodologies". Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/28998.

Texto completo
Resumen
The stable free radical polymerization methodology for production of controlled macromolecules was investigated using a novel monomer, 2-vinylnaphthalene. Initial polymerizations resulted in molecular weight distributions typical of conventional free radical polymerization techniques (>2.0). Manipulation of the initiator concentration and the molar ratio of initiator to nitroxide demonstrated no significant control over the resulting polymer products. Analysis of the polymerization kinetics for a 2-vinylnaphthalene polymerization performed in the presence and absence of the free radical initiator revealed identical monomer consumption profiles as well as pseudo first order kinetics indicating a significant degree of the thermal polymerization was occurring at the polymerization temperature (130°C). Comparison of the thermal polymerization propensity of 2-vinylnaphthalene and styrene revealed an increased tendency for 2-vinylnapthahlene to undergo thermal polymerization. Styrene is considered highly active in its propensity to thermally polymerize. However, an Arhenius analysis using in situ FTIR was employed to determine the activation energy for the thermal polymerization of styrene and 2-vinylnaphthalene. The 2-vinylnaphthalene activation energy for thermal polymerization was determined for the first time to be almost 30 kJ/mol less than styrene. A novel modified Mayo mechanism was proposed for the 2-vinylnaphthalene thermal initiation mechanism. Moreover, this thermal initiation was employed to initiate nitroxide mediated polymerizations of styrene. This first use of a 2-vinylnaphthalene initiating system resulted in polystyrene with a large macrocyclic initiating fragment. The presence of the initiating moiety was studied using both UV-Vis spectroscopy and 1H NMR spectroscopy. The extension of stable free radical polymerization to the acrylate monomer family was examined using a novel nitroxide mediator, N-tert-butyl-N-[1-diethylphosphono-(2,2-dimethylpropyl)] nitroxide (DEPN). The synthesis of DEPN was monitored using in situ FTIR spectroscopy to determine optimum reaction conditions. The purified nitroxide was subsequently employed in the synthesis of various block and random acrylate copolymers. The production of a unique amphiphilic block copolymer consisting of acrylic sequences was achieved. Poly(t-butyl acrylate-b-2ethylhexyl acrylate-b-t-butyl acrylate) was synthesized using the SFRP process. The t-butyl functionalities were subsequently removed in a post-polymerization acid catalyzed hydrolysis. The effect of steric bulk and electronic factors on the resulting SFRP process was also investigated and revealed similar polymerization kinetics for various alkyl acrylates. However, addition of a hydroxyl containing monomer, 2-hydroxyethyl acrylate, resulted in an increase in the polymerization rate up to 2 times. The rate enhancement was attributed to hydrogen bonding effects and this was confirmed using the unprecedented addition of dodecanol, which also demonstrated a significant rate enhancement. Block copolymers were also achieved using a novel difunctional nitroxide synthesized from 4-hydroxy TEMPO and 1,6-hexamethylene diisocyanate. The identity of the nitroxide was confirmed using mass spectrometry and 1H NMR. The dinitroxide was used in the polymerization of styrene and subsequently used to produce symmetric ABA triblock copolymers with t-butyl styrene using a unique two-step polymerization route. In addition, the dinitroxide demonstrated an increased tendency for decomposition due to the complex mediation equilibrium. The decomposition was studied using GPC to evaluate the decomposition effects on the polymerization. Results of the research efforts presented herein are written as individual research reports with contributing authors and pertinent literature reviews presented at the beginning of each chapter.
Ph. D.
Los estilos APA, Harvard, Vancouver, ISO, etc.
35

Bergerbit, Cédric. "RAFT polymerization of ethylene for the synthesis of polar-apolar olefin block copolymers". Thesis, Lyon, 2019. https://n2t.net/ark:/47881/m6s181w9.

Texto completo
Resumen
La synthèse de copolymères à blocs, comprenant un bloc semi-cristallin de polyéthylène (PE) apolaire et un bloc polaire (poly(acétate de vinyle) (PAcV), poly(méthacrylate de méthyle) (PMAM), poly(oxide d’éthylène) (POE)) a été étudiée par polymérisation RAFT. L’étude préliminaire de l’homopolymérisation de l’éthylène en conditions relativement douces (T = 70 – 80 °C, P = 200 bar) a révélé que l’utilisation d’agents de transfert de chaîne (ATC) de type xanthates aromatiques conduit à une perte de fonctionnalité des extrémités de chaînes au cours de la polymérisation, conséquence directe de réactions de terminaison se produisant sur le radical intermédiaire. L’utilisation de dithiocarbamates aromatiques a permis de s’affranchir de ce mécanisme parasite et pour la première fois des chaînes de PE présentant une fonctionnalité de bout de chaîne proche de 100%. Des ATCs macromoléculaires polaires, obtenus avec les agents de transfert de chaînes identifiés au cours de l’étude préliminaire, ont ensuite été utilisés pour la synthèse de copolymères à blocs dans le carbonate de diméthyle (DMC), un solvant organique peu transférant. Le rôle clé de la thermodynamique du milieu de polymérisation (mélange DMC/éthylène supercritique à 200 bar) a alors été mis en évidence. En effet, les macro-ATCs sont insolubles dans un tel milieu, ce qui a conduit à la formation d’un mélange d’homopolymères. La diminution de la pression de polymérisation (P < 100 bar) a toutefois permis d’éviter ce phénomène et les copolymères PVAc-b-PE, PMMA-b-PE et PEO-b-PE attendus ont été obtenus. Des propriétés d’auto-assemblage ont été mises en évidence et des morphologies de type fibre ont été obtenues pour les copolymères PMMA-b-PE et PEO-b-PE synthétisés dans le DMC, permettant d’envisager un mécanisme de type auto-assemblage induit par la polymérisation (PISA). Le passage en milieu aqueux en utilisant le macro-ATC hydrosoluble PEO a permis l’observation de morphologies de type sphériques, vésicules ou encore ellipsoïdes selon le rapport molaire macro-ATC/amorceur utilisé
The synthesis of polar-apolar olefin block copolymers, combining a semi-crystalline polyethylene (PE) block and a polar block (poly(vinyl acetate) (PVAc), poly(methyl methacrylate) (PMMA), poly(ethylene oxide) (PEO)) was investigated by RAFT polymerization. A preliminary study on ethylene homopolymerization revealed parasite cross-termination reactions happening at the intermediate radical, resulting in the loss of chain-end fidelity when using aromatic xanthates as chain transfer agents (CTA) under relative mild conditions (T = 70 – 80 °C, P = 200 bar). The extent of cross-termination was greatly reduced with aromatic dithiocarbamates, and for the first time, PE chains with a high livingness were obtained. These first results were used to equip polar macromolecular CTAs (PVAc, PMMA, PEO), with selected aromatic xanthates and dithiocarbamates, that were further used for block copolymerization with ethylene in a low-transferring organic solvent (dimethyl carbonate, DMC). A critical influence of the ethylene pressure was evidenced as block polymerization at 200 bar could not be achieved due to solubility issues in the resulting supercritical DMC/ethylene mixture. This was circumvented by performing the block copolymerization below the supercritical point of the mixture (P < 100 bar) and well-defined PVAc-b-PE, PMMA-b-PE and PEO-b-PE copolymers were eventually obtained. The block copolymers were found to feature self-assembly properties and worm-like morphologies were observed for PMMA-b-PE and PEO-b-PE synthesized in DMC, hinting at a plausible polymerization-induced self-assembly (PISA) mechanism. The successful switch from DMC to water for the synthesis of PEO-b-PE copolymers enabled the observation of various particle morphologies: spheres, vesicles and ellipsoidal particles, depending on the initial macro-CTA:initiator molar ratio
Los estilos APA, Harvard, Vancouver, ISO, etc.
36

Xu, Guangjuan [Verfasser] y Michael [Akademischer Betreuer] Buchmeiser. "Functional polyolefins prepared by group 4 diamide complexes through tandem ring-opening metathesis, vinyl insertion polymerization / Guangjuan Xu. Betreuer: Michael Buchmeiser". Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2014. http://d-nb.info/1052020992/34.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
37

Mumtaz, Muhammad. "Synthesis of poly(3,4-ethylenedioxythiohene), polyaniline and their metal-composite nano-objects by dispersion polymerization". Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13854/document.

Texto completo
Resumen
Dans l'objectif d'améliorer la mise en forme des polymères semi-conducteurs tels que le poly (3,4-éthylènedioxythiophène) et la polyaniline, nous avons développé leur synthèse par polymérisation en dispersion de leurs monomères respectifs en utilisant le poly(oxyde d'éthylène), le poly (vinyl alcool), le poly [(N-vinylpyrrolidone)-co-(vinyl alcool)] et le poly [(N-vinylpyrrolidone)-b-(vinyl alcool)] comme stabilisants réactifs dans des milieux dispersants aqueux. Des nano-objets de nature et de structure bien définis ont été obtenus. Afin de moduler la conductivité et les propriétés opto-électroniques de ces nano-objets, leurs composites avec des métaux tels que l'or, l'argent et le cuivre ont été préparés en utilisant les sels métalliques correspondants comme co-oxydants au cours de la polymérisation en dispersion. La morphologie des nano-objets a notamment été évaluée par Microscopie Electronique en Transmission, Microscopie Electronique à Balayage, et Microscopie à Force Atomique. Le nature cœur-écorce de ces nano-objets, le niveau de dopage et la présence de métaux dans les nano-composites ont été examinés par spectrométrie de photoélectrons induits par rayons X
With the objective to improve the processability of “stiff” semi-conducting polymers, well defined poly(3,4-ethylenedioxythiophene) and polyaniline core-shell nano-objects were synthesized by dispersion polymerization of their respective monomers using poly(ethylene oxide), poly(vinyl alcohol), poly[(N-vinylpyrrolidone)-co-(vinyl alcohol)] and poly[(N-vinylpyrrolidone)-b-(vinyl alcohol)]-based reactive stabilizers in aqueous dispersant media. In order to improve the conductivity and opto-electronic properties of these nano-objects, their composite with gold, silver and copper were prepared using the metal salts as co-oxidants during dispersion polymerization. The morphology of the nano-objects was observed by microscopy analyses such as Transmission Electron Microscopy, Scanning Electron Microscopy, and Atomic Force Microscopy. The core-shell nature of these nano-objects, doping level and the presence of metals in the nano-composites were examined by X-rays Photoelectron Spectroscopy
Los estilos APA, Harvard, Vancouver, ISO, etc.
38

Fan, Weijia. "Design and Utilization of New Organotellurium Chain Transfer Agents for Advanced Polymer Synthesis". Kyoto University, 2019. http://hdl.handle.net/2433/242914.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
39

Wang, Min [Verfasser] y Michael [Akademischer Betreuer] Buchmeiser. "Synthesis of half-sandwich group 4 transition metal catalysts for tandem ring-opening metathesis/vinyl insertion polymerization / Min Wang ; Betreuer: Michael Buchmeiser". Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2016. http://d-nb.info/1118369459/34.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
40

Haraldsson, Klas Tommy. "Fabrication of polymeric microfluidic devices via photocurable liquid monomers". Doctoral thesis, Stockholm : Fibre and Polymer Technology, Department of Chemical Engineering and Technology, Royal Institute of Technology (KTH), 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-466.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
41

Lu, Yangtian. "Synthesis of structurally controlled hyperbranched polymers through the design of new monomers with hierarchical reactivity". Kyoto University, 2019. http://hdl.handle.net/2433/243314.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
42

Brown, Nicole Robitaille. "Understanding the Role of N-Methylolacrylamide (Nma) Distribution in Poly(Vinyl Acetate) Latex Adhesives". Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/26446.

Texto completo
Resumen
This work addresses the distribution of N-methylolacrylamide (NMA) units in crosslinking poly(vinyl acetate) (PVAc) adhesives. In this case, distribution refers to the three potential locations of polymerized NMA units in a latex: the water-phase, the surface of polymer particles, and the core of the polymer particles. The objective is to identify the distribution of NMA in three latices and to determine whether NMA distribution correlates with durability related performance. NMA distribution was studied via a series of variable temperature solution NMR experiments, while the durability-related performance was studied via mode I fracture mechanics tests. Studying the distribution of NMA required the use of isotopically labeled NMA. Both 15N-NMA and 13C, 15N-NMA were synthesized. Three NMA/vinyl acetate (VAc) latices were prepared. The NMA feed strategy was varied during each of the three emulsion copolymerizations. Latex characterization methods including differential scanning calorimetry (DSC), rheometry, particle size analysis, and scanning electron microscopy (SEM) were used to study the three latices. The solution NMR method to identify NMA distribution was performed on untreated latices and on washed latices. Washing techniques included membrane dialysis and centrifugation. Results revealed that the three latices had different NMA distributions, and that the distributions were related to the expected differences in microstructure. Latex 3 had ~ 80% core-NMA, while Latex 2 had ~ 80% surface-NMA. Latex 1 had a high proportion of surface-NMA (~60%), but also had the highest proportion of water-phase NMA (~ 20%). This high proportion of water-phase NMA could be responsible for the unique morphology Latex 1 exhibited in SEM studies. Mode I opening fracture mechanics studies were used to study adhesive performance. Specimens were analyzed after exposure to accelerated aging treatments. Latex 2 and Latex 3 exhibited very similar results, despite having very different NMA distributions. All three latices showed good durability related performance. In Latex 2 and Latex 3, the critical strain energy release rates (Gc) after accelerated aging treatments were statistically the same as the Gc of the control specimens. The most interesting finding was that the Latex 1 Gc values were significantly higher after accelerated aging. Latex 1 also had the highest proportion of water-phase NMA. Bondline images and SEM micrographs both indicated that the integrity of Latex 1 was least affected by the accelerated aging treatments.
Ph. D.
Los estilos APA, Harvard, Vancouver, ISO, etc.
43

Pfukwa, Rueben. "Synthesis and characterization of telechelic hydroxyl functional poly (N-vinylpyrrolidone)". Thesis, Link to the online version, 2008. http://hdl.handle.net/10019/890.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
44

Huser, Julien. "FUI Ecoating. Comprehension of the Scale Formation Mechanism during the Suspension Polymerization of Vinyl Chloride Monomer and Development of a Durable Protective Polymer Coating". Thesis, Mulhouse, 2013. http://www.theses.fr/2013MULH4032.

Texto completo
Resumen
La production de poly(chlorure de vinyle) (PVC) sous forme de suspension chez INEOS ChlorVinyls est réalisée en réacteur fermé agité, dont les parois sont en émail ou en acier inoxydable. Il se forme en cours de polymérisation un dépôt de PVC (croûte) sur les parois du réacteur qui génère de nombreux inconvénients. Afin de limiter cet encroûtement, INEOS ChlorVinyls et l’ensemble des producteurs de PVC appliquent à chaque batch (par exemple pour INEOS ChlorVinyls 50 fois par jour pour ses 22 réacteurs) un revêtement organique. L’application systématique du revêtement et la formation de croûtes ont des conséquences économiques non négligeables (arrêts de production, coût de main d’œuvre et matière, coût de traitement des déchets, qualité du PVC contaminé par le revêtement…).La compréhension du phénomène d’encroûtement en vue de développer un revêtement permanent devient donc nécessaire pour améliorer la qualité des produits, diminuer les coûts et dégager un avantage concurrentiel favorable à INEOS vis-à-vis de ses concurrents. Le sujet de thèse a été divisé en deux parties bien distinctes avec premièrement l’étude du mécanisme d’encroûtement et la mise en place d’un scénario permettant d’expliquer de manière physique et chimique la formation de la croûte sur les parois du réacteur. Une seconde partie a été dédiée au développement d’un revêtement polymère avec la sélection d’un système résistant au milieu réactionnel de polymérisation en suspension du chlorure de vinyle puis à l’optimisation de l’adhésion du revêtement polymère sur acier inoxydable afin d’obtenir des performances maximales et durables
The suspension synthesis of PolyVinyl Chloride (S-PVC) at the INEOS ChlorVinyls facility in Mazingarbe (FRANCE) is realized thanks to a closed-reactor technology with reactor walls made of stainless steel or enamel. One of the major problems during the production of PVC by suspension polymerization is the formation of a deposit (called crust or scale) on the reactor walls. The formation of scale leads to numerous sorts of drawbacks like a decrease of the reactors’ productivity, the need to clean the reactors after each batch, the exposure of the operators to VinylChloride Monomer (VCM) which is classified CMR, some quality issues… At the moment, a coating is applied before each batch (50 times per day for the 22 reactors at Mazingarbe) in order to lower the amount of scale formed during the S-PVC batch. The application of the coating added to the formation of scale leads to important extra costs. The comprehension of the scale formation mechanism with the aim of then developing a durable protective coating becomes a priority in order to increase the final product quality, lower the costs and gain a competitive advantage for INEOS ChlorVinyls. The Ph.D. subject was divided into two parts with the first year dedicated to the comprehension of the scale formation mechanism and the establishment of a complete scenario explaining the formation of scale from a chemical and physical point of view. The second part of this project was dedicated to the development of a polymer coating with the selection of an adapted polymer candidate and then the optimization of its adhesion onto stainless steel in order to obtain the optimal performances and the durability of the coating
Los estilos APA, Harvard, Vancouver, ISO, etc.
45

Yaacoub, Saly. "Etude de couches hybrides photopolymérisables de type vinyl éther silane : Application à la fabrication de composants optiques intégrés". Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20175/document.

Texto completo
Resumen
Depuis plusieurs dizaines d'années, les matériaux hybrides organiques-inorganiques constituent une classe de matériaux particulièrement bien adaptée aux applications en optique intégrée. Le réseau minéral, élaboré par procédé sol-gel, confère au matériau la tenue mécanique. Quant au réseau organique, qui est réticulable par voie photochimique, il permet la formation des systèmes guidants. Des travaux antérieurs réalisés au sein de notre laboratoire ont montré le potentiel d'un matériau à base d'un précurseur hybride 2-(3,4 epoxycyclohexylethyltrimethoxysilane) (EETMOS) pour l'application en optique intégrée. Bien que la qualité des composants réalisés à 1,31µm se soit révélée satisfaisante, un problème subsiste : une trop forte atténuation à 1,55 µm. La transmission optique autour de ces longueurs d'ondes est limitée par la présence des groupements OH et CH aliphatiques.L'objectif principal de ce travail est de développer une nouvelle génération de matériaux hybrides avec une très grande réactivité et de diminuer la quantité de groupements impliqués dans l'atténuation. Nous avons choisi la fonction vinyl éther comme fonction organique grâce à sa grande réactivité par voie cationique en comparaison avec la fonction époxyde. Nous avons étudié la double fonctionnalité de polymérisation du nouveau matériau hybride à base d'un vinyl éther silane. En premier lieu, les réactions d'hydrolyse et de polycondensation du sol ont été suivies par la spectroscopie RMN liquide du Si-29 en fonction du temps, de la température et du pH de l'eau impliquée dans l'hydrolyse. Le but était d'obtenir le plus haut taux d'oligomère multifonctionnel possible et le minium de groupement OH. La photopolymérisation de type cationique de la fonction vinyl éther a ensuite été étudiée, en utilisant la spectroscopie d'absorption dans l'infrarouge moyen. En présence du photoamorceur diaryliodonium, la photopolymérisation a été étudiée en suivant l'évolution de la bande d'absorption de la double liaison vinyl éther avant et après irradiation. La photopolymérisation cationique est rapidement initiée dès le début de l'exposition aux UV, ce qui prouve la réactivité important de la fonction vinyl éther. En utilisant la spectroscopie d'absorption dans le proche infrarouge, les résultats montrent des niveaux d'atténuation très prometteurs pour l'utilisation de ce matériau en optique intégré à 1,31 et 1,55 µm
In the last few years, organic-inorganic hybrid materials were particularly attractive for integrated optical circuits. Hybrid network could be prepared by the formation of inorganic and organic network simultaneously through sol-gel technique and photopolymerization process.A composition based on [2-(3, 4 epoxycyclohexylethyltrimethoxysilane)] has already allowed the fabrication of optical integrated devices. The organic polymerization is on a cationic way. Results show the contributions of OH and aliphatic CH groups to the attenuation in the third telecommunication window located at 1,55 µm.The main objective of this work is to remove this difficulty by developing a new generation of hybrid materials with a very high reactivity and low amount of groups involved in the attenuation. We have chosen vinyl ether function as an organic part because of their well known high polymerization rates via cationic way which are faster than the epoxide function and which lead to no OH groups generation and a very low aliphatic CH groups introduction.In this work, we study the dual functional structure of a new vinyl ether alkoxysilane hybrid precursor. Firstly, hydrolysis and polycondensation of vinyl ether based solution are followed by liquid and solid Si-NMR spectroscopy. The kinetic reaction is followed as a function of time, temperature and pH of the water involved in the hydrolysis, in order to obtain the highest reactive multifunctional oligomer and the lowest OH groups. Secondly, results of the cationic photopolymerization of vinyl ether- based monomers are also reported, using middle infrared spectroscopy. In the presence of diaryliodonium photoinitator, the photopolymerization is studied by monitoring the absorption band of vinyl ether double bond before and after irradiation. The cationic photopolymerization occurs rapidly upon UV-exposure and vinyl ether monomers proved to be very effective monomers. Using near infrared spectroscopy, results show promising attenuation for the use of this material in integrated optic at 1,31 µmand 1,55 µm
Los estilos APA, Harvard, Vancouver, ISO, etc.
46

Illanes, Teresa. "Synthesis of Novel Degradable Polymers for Tissue Engineering by Radical Polymerization : Synthesis and characterization of 2-methylene-1,3-dioxepane and copolymerization thereof with vinyl acetate followed by polymer characterization and hydrolysis". Thesis, KTH, Skolan för kemivetenskap (CHE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-33107.

Texto completo
Resumen
The commercial field of radical polymerized polymers, such as polyvinyl alcohol, is very broad partly because they are easy to polymerize and cheap. One aspect that could improve their commercial range is to enhance their degradation rate. As the environmental aspect of polymers grows bigger an enhancement of biological degradation is a great improvement. This thesis deals with the prospect of polymerizing polyvinyl alcohol with degradable linkages in the main chain. In order to achieve the aim the monomer 2-methylene-1,3-dioxepane is successfully synthesized and characterized. The synthesis is followed by copolymerization of 2-methylene-1,3-dioxepane with vinylacetate at the feed compositions; 30/70, 50/50, 70/30 mol% respectively. The copolymerization was successful and reached over 90% conversion at the reaction time 3-4 hours with the conditions 60°C and 5mol% 2,2-Azobis(2-methylpropionitrile) as initiator. The copolymerization is followed by hydrolysis with potassium hydroxide or Candida Rugosa Lipase. The results show that chain scission occurs when the polymer is hydrolyzed by potassium hydroxide but not by lipase. There is also a tendency toward hydrolysis of the chain with lipase.
Los estilos APA, Harvard, Vancouver, ISO, etc.
47

Franco, Cilene Meinberg. "Pesquisa experimental sobre a polimerização via radical livre com iniciadores mono e difuncional". [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266156.

Texto completo
Resumen
Orientador: Liliane Maria Ferrareso Lona
Dissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Engenharia Quimica
Made available in DSpace on 2018-08-07T07:49:45Z (GMT). No. of bitstreams: 1 Franco_CileneMeinberg_M.pdf: 1835289 bytes, checksum: 8c7c34fee69d338538caffa2e9546741 (MD5) Previous issue date: 2006
Resumo: Iniciadores mono funcionais são largamente utilizados em polimerizações VIa radical livre. Muitas vezes, na busca de maiores produtividades, utilizam-se temperaturas de operação mais elevadas e/ou maiores concentrações iniciais de iniciador, que por conseqüência, geram polímeros com pesos moleculares mais baixos. O uso de iniciadores difuncionais permite o aumento da produtividade sem a redução no peso molecular do produto final, o que pode ser urna característica desejável. A pesquisa com iniciadores difuncionais é atual e de grande interesse industrial. O objetivo deste trabalho é analisar o efeito da funcionalidade do iniciador, no caso mono e difuncional, sobre a polimerização via radical livre, considerando corno caso estudo um polímero linear, o poliestireno, e um ramificado, o poli (acetato de vinila). Para isso, foram feitas, experimentalmente, reações de polimerização em ampolas de vidro (polimerização em massa), com o iniciador mono funcional (Luperox TBEC) e o di funcional (Luperox 531). Foram analisados também o efeito da temperatura de polimerização e a concentração de iniciador. Também neste trabalho é apresentado um estudo estatístico através de um Planejamento Fatorial, a fim de analisar o efeito das variáveis temperatura e concentração de iniciador na polimerização do estireno com iniciador difuncional. Observou-se, tanto para o estireno corno para o acetato de vinila, que quando utilizado o iniciador difuncional é possível obter conversões maiores, sem alterar o peso molecular médio mássico e numérico, sendo que em alguns casos pode se até obter um aumento no peso molecular. O uso de iniciador di funcional é também mais viável economicamente, pois apresenta melhores resultados frente ao monofuncional, mesmo quando utilizado em concentrações ou temperaturas menores do que as utilizadas com o iniciador mono funcional. É importante salientar o caráter inovador desta pesquisa, já que não foram encontrados, em literatura aberta, dados experimentais da polimerização do acetato de vinila (ou outro monômero que produza ramificações de cadeia longa) utilizando iniciadores difuncionais
Abstract: Monofunctional initiators are extensively utilized in free radical polymerization. In order to increase productivity, higher temperature or higher initial initiator concentration are used, therefore polymers with lower molecular weights are obtained. Bifunctional initiators increase the polymerization rate without decreasing the average molecular weight and this can be desirable. They are an important issue to be investigated and are of great interest to industries. The objective of this work is to analyze the effect of the functionality of the initiator, by using mono and bifunctional, in free radical polymerization, for linear polymer (poly styrene) and branched polymer (poly(vinyl acetate)). Polymerizations were experimentally performed in glass ampoules (bulk polymerization) using both mono(Luperox TBEC) and bi- (Luperox 531) functional initiators. The effects of temperature and initiator concentration were also analyzed for various polymerization conditions. This work includes a statistical study using the factorial design to analyze the effect of temperature and initiator concentration in styrene polymerization with bifunctional initiator. It is observed in this study, that high conversions with no effect in the molecular weigh of the dead polymer can be achieved using bifunctional initiators in the polymerization of styrene and vinyl acetate. In many cases, it is possible to obtain higher molecular weights. Bifunctional initiator can also be used to provide reduction costs to initiators. They showed better results than the monofunctional initiator when lower concentration or temperature lower were utilized.
Mestrado
Desenvolvimento de Processos Químicos
Mestre em Engenharia Química
Los estilos APA, Harvard, Vancouver, ISO, etc.
48

Dommanget, Cédric. "Polymérisation radicalaire contrôlée : le défi de l'éthylène". Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10216/document.

Texto completo
Resumen
Les travaux présentés dans cette thèse portent sur le contrôle de la polymérisation radicalaire de l'éthylène à basse pression (200 bar) et basse température (70 °C) et sur la synthèse de copolymères à blocs contenant au moins un segment de polyéthylène. Quatre techniques de polymérisation, couramment utilisées en ingénierie macromoléculaire, ont été étudiées : NMP, CMRP, RAFT/MADIX et ESCP. Nos études sur le nitroxyde SG1 (NMP) et le bis(acétylacétonate) de cobalt (CMRP) ont montré que ces composés sont inefficaces pour contrôler la polymérisation de l'éthylène. Un comportement inattendu du bis(acétylacétonate) de cobalt a cependant été mis en évidence. Il semblerait que ces complexes de cobalt favorisent les réactions de couplage entre les radicaux propagateurs. En revanche, la première polymérisation radicalaire contrôlée de l'éthylène a été atteinte grâce à l'utilisation de xanthates (RAFT/MADIX). Les polyéthylènes synthétisés possèdent des masses molaires qui augmentent linéairement avec la conversion et des dispersités faibles. Le caractère pseudo-vivant de la réaction a été démontré par la synthèse de copolymères à blocs poly(acétate de vinyle)-b-polyéthylène. L'utilisation de nitrones (ESCP) a également permis l'introduction d'une fonction réactive au centre des chaînes de polyéthylène et la synthèse de copolymères triblocs de type ABA, où les blocs latéraux A sont en polystyrène ou polyacrylate et le bloc central B est en Polyéthylène
The work presented in this thesis displays the controlled radical polymerization of ethylene at low temperature (70 °C) and low pressure (200 bar) and the synthesis of block copolymers featuring polyethylene segments. Four polymerization techniques, commonly used in macromolecular engineering, were studied: NMP, CMRP, RAFT/MADIX and ESCP. Our investigation of the use of SG1 nitroxide (NMP) and cobalt (II) acetylacetonate (CMRP) as controlling agents demonstrated their inability to control the polymerization of ethylene. Nonetheless, an unexpected reaction with cobalt (II) acetylacetonate was observed. The coupling reaction between propagating radicals appeared to be favored by the presence of this compound. On the other hand, the first controlled polymerization of ethylene was successfully achieved by using xanthate (RAFT/MADIX). A linear increase of molecular weight with conversion and low polydispersities were observed for the produced polyethylenes. The reaction was demonstrated to be a pseudo-living polymerization by the synthesis of block copolymers poly(vinyl acetate)-b-polyethylene. In addition, midchain-functionalized polyethylenes and ABA type block copolymers, with polystyrene or polyacrylate as the A block and polyethylene as the B block, were also prepared using nitrone based polymerization technique (ESCP)
Los estilos APA, Harvard, Vancouver, ISO, etc.
49

Carvalho, Antônio Carlos Sallarés de Mattos. "Desenvolvimento de processo contínuo de copolimerização em emulsão em reator tubular". Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-02062008-135006/.

Texto completo
Resumen
Os processos industriais de polimerização em emulsão são normalmente realizados em reatores batelada ou semi batelada ou em tanques agitados contínuos (CSTR). Os reatores contínuos têm a vantagem de terem menor porte e de propiciarem melhor controle de qualidade do produto através da redução de variações de batelada a batelada. Além disso, as oscilações periódicas autosustentadas na conversão de monômero e no tamanho da partícula, que são normalmente observadas em reatores do tipo CSTR, podem ser minimizadas em reatores tubulares mediante o uso de dispositivos de mistura estáticos adequados combinados com escoamento pulsado (oscilatório). O objetivo deste trabalho é apresentar o desenvolvimento de uma copolimerização em emulsão de acetato de vinila e acrilato de butila em uma coluna pulsada com pratos perfurados (CPPP). A fim de aumentar a sua flexibilidade operacional, a coluna é composta de 5 seções, cada uma apresentando controles independentes de alimentação lateral e temperatura. Dependendo da estratégia de alimentação de monômero, pode-se notar uma deriva de composição durante o processo de copolimerização em emulsão do acetato de vinila e acrilato de butila devido às grandes diferenças entre estes monômeros em suas razões de reatividade e nas solubilidades na fase aquosa. Neste caso, a CPPP propicia diferentes possibilidades de alimentação que permitem controlar a composição do copolímero através da alimentação do monômero mais reativo ao longo da coluna. Por esta razão, foi avaliado neste estudo o efeito do número de correntes de alimentação sobre as propriedades do polímero. Diferentes números de correntes laterais de alimentação de monômero foram empregadas nos ensaios experimentais. Diferenças na uniformidade da composição do copolímero podem ser notadas dependendo do número de correntes laterais de alimentação aplicadas em cada teste. A fim de permitir variações de temperatura, somente a temperatura de entrada das camisas de resfriamento foi fixada. Para simular as reações foi utilizado um modelo matemático desenvolvido baseado no modelo de escoamento pistonado (plug-flow) axialmente disperso. No presente trabalho, um balanço de energia foi incluído ao modelo matemático anterior de modo que a influência de diferentes perfis de temperatura pudesse ser considerada. O efeito das correntes laterais de alimentação de monômero sobre as propriedades do copolímero puderam ser previstas com suficiente precisão pelas simulações do modelo, as quais foram também validadas pelos resultados experimentais. Com base nas simulações matemáticas, um perfil ótimo de alimentação pôde ser calculado e experimentalmente aplicado na CPPP permitindo a produção de um copolímero mais homogêneo. Os resultados também permitiram a validação do modelo matemático como uma ferramenta confiável na predição de ensaios experimentais. Além disso, as vantagens da CPPP puderam ser verificadas pelo seu desempenho adequado como reator tubular para processos contínuos de copolimerização em emulsão. Finalmente, os resultados indicaram a possibilidade de melhorias adicionais nas propriedades do polímero através do emprego de diferentes temperaturas e perfis de alimentação de outros reagentes ao longo da coluna.
Industrial emulsion polymerization processes are usually performed in batch or semi-batch stirred tanks, or in continuous stirred tank reactors (CSTR). Continuous reactors have the advantage of being smaller and providing a better product quality control by the reduction of the batch-to-batch variations. In addition, periodical self-sustained oscillations in monomer conversion and in particle size that are usually observed in CSTR can be minimized in tubular reactors presenting good radial mixing. Such conditions can be achieved in tubular reactors by using adequate static mixing devices combined with pulsed (oscillatory) flow. The aim of this work is to report the development of a continuous emulsion copolymerization of vinyl acetate and butyl acrylate performed in a pulsed sieve plate column (PSPC). In order to improve its operational flexibility, the column is composed of five sections, each one presenting independent lateral feed and temperature controls. Depending on the monomer feeding strategy, a composition drift can be noticed during the emulsion copolymerization process of vinyl acetate and butyl acrylate, due to the large differences in reactivity ratios and aqueous phase solubility between these monomers. In this case, the PSPC provides different operational feeding possibilities which allow controlling the copolymer composition by feeding the more reactive monomer along the column. For this reason, in this study the effect of the number of lateral feed streams on the polymer properties was evaluated. Different numbers of lateral monomer feed streams were employed in the experimental runs. Differences in the uniformity of the copolymer composition can be noticed along the reactor depending on the number of lateral feed streams applied in each test. In order to allow temperature variations, during each reaction only the inlet temperature of the cooling jackets was fixed. A developed mathematical model based on the axially dispersed plug-flow model was used to simulate the reactions. In the present study the energy balance was included in the mathematical model so that the influence of different temperature profiles could be taken into account. The effect of lateral monomer feed streams over the copolymer properties could be predicted with sufficient accuracy by model simulations which were also validated by the experimental results. Based on mathematical simulations, an optimal feeding profile could be calculated and experimentally applied in the PSPC allowing the production of a more homogeneous copolymer. The results also permitted the validation of the mathematical model as a reliable tool in the prediction of experimental runs. Furthermore, the advantages of the PSPC could be verified by its adequate performance as a tubular reactor for continuous emulsion copolymerization processes. Finally, the results indicate the possibility of further improvements in other polymer properties by employing different temperature and feeding profiles of other reagents along the column.
Los estilos APA, Harvard, Vancouver, ISO, etc.
50

Liu, Chenwei. "Synthesis of hyperbranched polymethacrylates by a bromoinimer approach". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1516719917076675.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
También puede estar interesado en las bibliografías sobre el tema "Vinyl polymerization" para otros tipos de fuentes:
Artículos de revistas Libros
Ofrecemos descuentos en todos los planes premium para autores cuyas obras están incluidas en selecciones literarias temáticas. ¡Contáctenos para obtener un código promocional único!

Pasar a la bibliografía