Extensive theoretical and experimental investigations and industrial product development efforts continue to advance our knowledge about the general features of emulsion polymerization mechanisms and kinetics. The process of emulsifier free emulsion polymerization is described in. The concentrations of surfactant and initiator were varied during the runs. The polymerization is usually carried out using water as the dispersion medium. The theory and experiments are in good qualitative agreement for the conversion rate prior to comple tion of particle formation. The theoretical predictions are compared to new experimental data and to those from the literature. Brownian coagulation is the predominant mechanism in emulsion polymerization. Results showed that it is possible to obtain high conversions with. Towards a consistent mechanism of emulsion polymerizationnew. Machado, in reference module in materials science and materials engineering, 2017. Shedding light on the different behavior of ionic and. Independently, yurzhenko and co workers developed similar ideas on the mechanism of emulsion polymerization. Special emphasis is placed on the particle nucleation, the chemical structure of the nucleating species, the change of latex, particle and polymer properties as well as the development of particle morphology with polymerization time.
Experimental data in support of continuous microwave. Pdf a comprehensive experimental study of surfactantfree. Pdf on jan 17, 2018, abdelaziz nasr moawed bakr elhoshoudy and. The latter are similar compounds and both behave like surfactants when they are not in solution. Surfactants prevent radicalscavenging reactions that stop the polymerization. All of the surfactants were ethoxylated to an average of 30 moles starting with nonylphenol, octylphenol, secondary, modified linear, isotridecyl, and a branched fischertropsch based. Therefore, both experimental studies and reaction simulations were performed. Possible explanations for this behaviour have been proposed and tested in this work, by measuring radicalloss rates directly with. Although this method is very similar to suspension polymerization, the two schemes differ in two important aspects. However, at present, some key points at issue such as particle nucleation and. Another step towards nonmicellar nucleation theory. In our previous reports, we carried out a series of experimental investigations about particle.
Experimental data in support of continuous microwave effect. Isothermal emulsion polymerization at 60c of styrene in a batch reactor were studied by using sodium lauryl sulfate as surfactant and potassium persulfate as initiator source. The available data confirm the theoretical prediction that particle nucleation stops after a very small amount of polymer is formed, of the order of 0. Results showed that it is possible to obtain high conversions with rather low residence times in the pspc.
Control of emulsion polymerization reactors, aiche journal. The main objective of this work is to study the kinetics of vinyl acetate va emulsion polymerization reactions performed in this pspc. Although surfactants are known to play a vital role in polymerization reactions carried out in dispersed media, many aspects of their use are poorly understood, perhaps none more so than the vastly different action of ionic and nonionic surfactants in emulsion polymerization. Adaption of the mechanism of emulsion polymerization to new experimental results. Chemical engineering 160260 polymer science and engineering. Particle nucleation and growth in butadiene emulsion polymerization.
Comprehensive experimental results are presented for surfactantfree emulsion polymerization of styrene with watersoluble, ionic initiators. Efficacy of initiation by persulfate in vinyl acetate emulsion polymerization. Tromsdorff effect or autoacceleration autoacceleration usually occurs in radical chain polymerizations and normally in bulk polymerization. However, these results are consistent with a mechanism in which the. The following four mechanisms for particle nucleation. Particle formation in ab initio raft mediated emulsion. Submissions are welcome on fundamental experimental or theoretical investigations of emulsion polymerization and related heterogeneous polymerizations including miniemulsion, microemulsion, suspension and inverse emulsion, on control of emulsion polymerization at the molecular or colloidal level, on application of emulsion polymerization for. Van dik hoff kinetics of emulsion polymerization 7 erally accepted, is based on the work done by harkins 29 and his collaborators during world war ii, published in 1947. Microemulsion and miniemulsion polymerization differ from emulsion polymerization in that the particle sizes are smaller 1030 and 30100 nm, respectively, vs. On the basis of the experiments with sls as emulsifier it is suggested that the mechanism of vinyl acetate emulsion polymerization is similar to that of vinyl chloride. Emulsion polymerization is a heterogeneous freeradical process in which the kinetic events take place simultaneously in more than one phase. Kaler center for molecular and engineering thermodynamics, department of chemical engineering, university of delaware, newark, delaware 19716. In the last years the concept of the mechanism of emulsion polymerization 4.
Inhibitors were removed from the styrene using a commercial inhibitor removal column aldrich, carbon disulfide was purified with several freezethaw cycles and. Control of emulsion polymerization reactors dimitratos, john. The following is the latex recipe used for testing various surfactants in emulsion systems. The most common type of emulsion polymerization is an oilinwater emulsion, in which droplets of monomer the oil are emulsified with surfactants in a continuous phase of water. Mechanism of emulsion polymerization rubber division, acs.
The most important result is the discovery of spontaneous emulsification leading to monomer droplets even in the quiescent styrene in water. This is a true copy of the dissertation, including any required final revisions, as accep. This study provided experimental results that show, rather conclusively, that emulsion formation is a result of surfactantlike behaviour of the polar and asphaltene compounds. Mechanism of coreshell emulsion polymerisation request pdf. Although emulsion polymerization has been studied and used for several decades, progress has been slow. Independently, yurzhenko and co workers developed similar ideas on the mechanism of emulsion polymerization reactions 67, 70. Polymer particle size distributions in continous emulsion. Advantages thermal and viscosity problems are minimized due to the high heat capacity and ease of stirring of the continuous aqueous phase. The present form of the theory does not apply to all monomers, initiators, surfactants and reaction conditions commonly used in the practice of emulsion polymerization although its predictions are in good accord with experimental results obtained with model systems complying with the assumed conditions. Pdf a comprehensive experimental study of surfactant. The polymerization evolution was followed as samples were taken at regular intervals. Introduction it has been emphasized in the authors previous paper1 that the kinetics of the continuous emulsion polymerization of styrene is by no meanssilimar to that of the batch operation.
In the work described in this thesis batch emulsion polymerization has been investigated from an engineering point of view with the objective to improve the operation of current processes and to allow for improvements in the development of novel emulsion polymerization processes. This in turn lowers the effective termination rate k. The dynamics of batch and continuous emulsion polymerization. A comprehensive experimental study of surfactantfree emulsion polymerization of styrene. Initiator systems effect on particle coagulation and particle. The focus here is on emulsion homopolymerization, and we. Therefore, in a plp experiment the chains that suffer back. The application of atypical experimental methods such as conductivity measurements, optical microscopy, and nonstirred polymerizations to investigations of the classical batch ab initio emulsion polymerization of styrene revealed astonishing facts. I experimental program with different monomer and emulsifier systems has been combined with the development of a comprehensive dynamic model which is, in principle, applicable for emulsion polymerization in any reactor system. A kinetic study of the emulsion polymerization of vinyl. Emulsion polymerization description of process utility.
The control of emulsion polymerization is a challenging problem due to major limitations encountered in its modeling and on. Dec 03, 2007 the application of atypical experimental methods such as conductivity measurements, optical microscopy, and nonstirred polymerizations to investigations of the classical batch ab initio emulsion polymerization of styrene revealed astonishing. In this study, a series of experiments were performed to. Pdf kinetics of vinyl acetate emulsion polymerization in. Experimental results using a pulsed tubular reactor are presented. Towards a consistent mechanism of emulsion polymerization new experimental details article pdf available in colloid and polymer science 2865. This makes emulsion polymerization less detrimental to the environment than other. One of the most widely used methods of manufacturing vinyl polymers, emulsion polymerization involves formation of a stable emulsion often referred to as a latex of monomer in water using a soap or detergent as the emulsifying agent. A comprehensive experimental study of surfactantfree.
Pdf kinetics of vinyl acetate emulsion polymerization in a. The polymerization is initiated by free radicals arising from the addition of an initiator. Emulsion polymerization is a polymerization process with different applications on the industrial and academic scale. Emulsion polymerization in practice is a very simple process, consisting of a reaction system in which the monomers are stabilized via the use of surfactants and are dispersed in an aqueous phase. Emulsion polymerization of butyl acrylate chemical papers.
Short course advances in emulsion polymerization and latex technology a oneweek short course held at the hotel belvedere in the davos resort area of switzerland august 1721, 2020 course directors dr. Publishers pdf, also known as version of record includes final. View the article pdf and any associated supplements and figures for a period of 48 hours. The use of a pulsation source eliminates the reactor fouling and plugging issue that has occurred in previous investigations. Towards a consistent mechanism of emulsion polymerization. It involves application of emulsifier to emulsify hydrophobic polymers through aqueous phase by amphipathic emulsifier, then generation of free radicals with.
Emulsion polymerization is a type of radical polymerization that usually starts with an emulsion incorporating water, monomer, and surfactant. Now predominant process for vac, cr, sbr, acrylates,etc. Batch emulsion polymerization pure eindhoven university. Introduction to emulsion polymerization springerlink. Chapter 3 successful use of raft in emulsion polymerization 41 3. Sund the norwegian institute of technology, 7034 trondheim nth, norway abstract bulk and emulsion polymerization have as a common featufe that there are. Miniemulsion polymerization of acrylated methyl oleate for pressure. Emulsion polymerization of vinylidene fluoride 9 has been carried out by a heterogeneous reaction in the presence of a surfactant, the most suitable of which is a fluorinecontaining acid salt of a fluoroalkanoic. Abstract emulsion polymers are products by process whose main properties are. Control of emulsion polymerization reactors dimitratos. This article contains original experimental data, figures and methods to the study of microwaveassisted emulsion polymerization of styrene under the frame of enhanced microwave synthesis ems, has been examined to investigate the advantages of microwave mw power use in emulsion polymerization ergan et al. Emulsion polymerization an overview sciencedirect topics. Emulsion polymerization is an industrially important process for the production of polymers used as synthetic rubber, adhesives, paints, inks, coatings, etc. All monomer is in solution or in the particle phase.
With the polymer emulsion shown in the experiment the effect has been driven to. Tromsdorff effect or autoacceleration mit opencourseware. Emulsion polymerization, like suspension polymerization, is a two phase reaction consisting of a dispersion medium and a dispersed phase which is the monomer. Pdf emulsion polymerization mechanism researchgate.
1176 822 1345 1428 518 1211 1190 1437 779 1225 1517 1296 1160 1272 1487 656 8 1203 161 750 817 690 814 669 48 230 619 997 255