Styrene Emulsion Polymerization above the CMC: New Evidence on Particle Nucleation by means of AFFFF

Carro, Shirley; Herrera‐Ordóñez, Jorge

doi:10.1002/marc.200500707

Cited by 15 publications

(13 citation statements)

References 30 publications

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“…Emulsion polymerization with the least amount of water‐soluble monomers (e.g., carboxylic acids) prevents unwanted polymerization in the continuous phase and undesirable particle morphologies at the end of process and, hence, is most favorable 18. In addition, an excess amount of emulsifier, much higher than the critical micelle concentration, causes compact micellar structures and results in unbalanced dynamic transportation of monomers 19. Hence, we were not able to carry out experimental design item 6.…”

Section: Methodsmentioning

confidence: 99%

Latex dispersability index

Khorassani¹,

Afshar‐Taromi²,

Pourmahdian³

2010

J of Applied Polymer Sci

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The pigment loading capacity (PLC) of dispersion binders is an important factor in the formulation of a latex paint. However, there has been no reliable method for the quantitative evaluation of this property; this has led to difficulty in comparing latex binders in this regard. In this article, a new parameter, the latex dispersability index (LDI), is proposed as a quantitative measure of PLC of latex binders. In this test method, the capability of latex to disperse pigments (or extenders) is quantified on the basis of the idea of the minimum viscosity method for dispersants. The face-centered cube experimental design was used to synthesize 26 binders. On the basis of this design, the synthesized latexes had a maximum diversity of properties, especially with regard to PLC. The binders were formulated with three mineral powders (i.e., TiO 2 , CaCO 3 , and talc). The curves of viscosity versus mass of the resin for all of the samples were prepared. The general trend of the curves was universal and only depended on the nature of the powders. The geometry of the curves and PLC had quantitative correlations. To make a quantitative correlation between the curves and PLC, LDI was defined as a function of the area under the curve, the height of the curve, and the length of the end point. Four ranges of LDI were assigned to the conventional quantitative phrases for PLC. The usefulness of this parameter was then verified by some well-known commercial binders with different PLCs. The results were in a good agreement with the expected behaviors.

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Section: Methodsmentioning

confidence: 99%

Latex dispersability index

Khorassani¹,

Afshar‐Taromi²,

Pourmahdian³

2010

J of Applied Polymer Sci

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“…They further reported that the maximum seen in the rate of nucleation profile by Varela de la Rosa et al could be attributed to the increase in the average number of radicals in the particles with particle size. Furthermore, the experimental results of Carro and Herrera‐Ordonez61 allowed it to be demonstrated that the number of particles is constant during interval II. The same was reported earlier by Harada et al75…”

Section: Relative Importance Of Different Nucleation Mechanismsmentioning

confidence: 95%

“…Coagulation is also not included in this model. Carro and Herrera‐Ordonez's61 work on a styrene emulsion polymerization above cmc by means of AF 4 suggested that coagulation of the primary particles was not as extensive as would be expected according to the coagulative mechanism. My own theoretical work21 based on DLVO theory to calculate the minimum surfactant coverage required for stability against coagulation showed it to be 4.6% for two species having a hypergeometric diameter of 5 nm, which corresponds to the micellar dimensions.…”

Section: Relative Importance Of Different Nucleation Mechanismsmentioning

confidence: 97%

“…Carro and Herrera‐Ordonez61 studied the number and size distribution of particles of a styrene emulsion polymerization above cmc by means of asymmetric flow‐field flow fractionation (AF 4 ). Bimodal PSDs were obtained, which suggested that coagulation of the primary particles was not as extensive as would be expected, according to the coagulative mechanism.…”

Section: Mechanisms Of Particle Nucleationmentioning

confidence: 99%

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Modeling of the particle size distribution in emulsion polymerization

Sood

2008

J of Applied Polymer Sci

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A mathematical model to predict the evolution of the latex particle size distribution in an emulsion polymerization reactor was developed. The mathematical framework is based on the population balance approach. It is general in framework, readily expandable to incorporate the physiochemical phenomena of interest to the reacting system of interest. The model includes such mechanistic details as (1) particle generation from radicals entering micelles; (2) particle size dependence of the radical entry mechanism; (3) coupling of the radical concentration in the aqueous phase and the particle phase; (4) determination of the particle phase radical concentration by radical entry into, exit from, and termination inside the particle; and (5) thermodynamic equilibrium between the monomer concentration in the aqueous phase and the particle phase. The model was solved efficiently with orthogonal collocation. Dynamic simulations were compared with experimental data taken from the literature for the emulsion polymerization of styrene (monomer), potassium persulfate (initiator), and sodium dodecyl sulfate (emulsifier). The variables considered were the total number of particles formed, duration of the nucleation period, conversion at the end of the nucleation period, variation of the monomer volume fraction in the particles with time, and conversion-time curves for different monomer, initiator, and emulsifier concentrations. Close agreement was found between the simulations and the experimental data.

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“…The FFF separation mechanism does not rely on adsorption or partitioning making this technique less likely to suffer sample loss. In the 40 years since its inception, FFF has been used in numerous applications including the separation of nanotubes [10,11], stem and cancer cells [12,13], pathogenic microorganisms [14][15][16][17], parasites [18][19][20], inorganic and polymeric particles [21,22] and the study of processes such as cell apoptosis [23], surface adsorption [24][25][26], and hydrodynamic forces [27]. Two textbooks have been dedicated to FFF [28,29] and review articles continue to be published addressing polymers [30,31], proteins [32,33], biotechnology [34], and particles (to be published, Encyclopedia of Particle Technology http:// nanoparticles.org/encyclopedia/).…”

Section: Introductionmentioning

confidence: 99%

Field‐flow fractionation of proteins, polysaccharides, synthetic polymers, and supramolecular assemblies

Williams¹,

Lee

2006

J of Separation Science

124

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This review summarizes developments and applications of flow and thermal field-flow fractionation (FFF) in the areas of macromolecules and supramolecular assemblies. In the past 10 years, the use of these FFF techniques has extended beyond determining diffusion coefficients, hydrodynamic diameters, and molecular weights of standards. Complex samples as diverse as polysaccharides, prion particles, and block copolymers have been characterized and processes such as aggregation, stability, and infectivity have been monitored. The open channel design used in FFF makes it a gentle separation technique for high- and ultrahigh-molecular weight macromolecules, aggregates, and self-assembled complexes. Coupling FFF with other techniques such as multiangle light scattering and MS provides additional invaluable information about conformation, branching, and identity.

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Styrene Emulsion Polymerization above the CMC: New Evidence on Particle Nucleation by means of AFFFF

Cited by 15 publications

References 30 publications

Latex dispersability index

Latex dispersability index

Modeling of the particle size distribution in emulsion polymerization

Field‐flow fractionation of proteins, polysaccharides, synthetic polymers, and supramolecular assemblies

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