Electrostatic and steric stabilization of PVC primary particles

Kiparissides, Costas; Moustakis, I.; Hamielec, A. E.

doi:10.1002/app.1993.070490309

Cited by 17 publications

(9 citation statements)

References 26 publications

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“…K i p a r i~s i d e s~~ developed a population balance model to describe the time evolution of the primary particle-size distribution as a function of the process variables such as temperature, ionic strength of the medium, and type and amount of steric stabilizer. Later on, Kiparissides et al 35 derived detailed expressions for the calculation of the coalescence rate constant of two colloidal particles by taking into account both electrostatic and steric stabilization forces.…”

Section: Ntrodu Ctl Onmentioning

confidence: 99%

“…The stability ratio was calculated according to the approximation proposed by Reerink and Overbeek. 41 The calculation of the total interaction energy V, which is given by the sum of the van der Waals attractive, V,, and electrostatic repulsive, VR, potentials, follows the developments described in Kiparissides et al, 35 Prindle and Ray, 42 Feeney et al, 43 and O t t e~i l .~~ For a given colloidal system, the attraction forces are assumed to be constant while the electrostatic repulsion forces can vary with the ionic strength of the medium. The reciprocal of the thickness of the electrical double layer, K , appearing in the calculation of V R , expresses the effect of the electrolyte concentration o n the repulsion forces.…”

Section: Calculation Of the Coalescence Rate Constantmentioning

confidence: 99%

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Dynamic simulation of primary particle‐size distribution in vinyl chloride polymerization

Kiparissides

Achilias

Chatzi

1994

J of Applied Polymer Sci

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SYNOPSISIn the suspension polymerization of vinyl chloride, colloidally stable primary particles are formed inside the polymerizing monomer droplets. The nucleation, growth, and aggregation of these particles are responsible for the formation of the internal particle morphology and associated properties, such as pore-size distribution, specific surface area, and plasticizer uptake. In the present investigation, a population balance model is derived describing the time evolution of the primary particle-size distribution in the polymerizing monomer droplets. The resulting integrodifferential equation accounts for the coalescence rate of electrically charged colloidal primary particles through the use of the Fuchs modification of the extended Smoluckowski coagulation equation. Simulation studies were carried out to determine both the effects of the model parameters and to afford a direct comparison of model predictions with experimental measurements of the time evolution of the primary particle-size distribution. The dependence of the total number and of the mean diameter of the primary particles on several process variables (i.e., the ionic strength of the medium, total particle charge, temperature, initial initiator concentration, and agitation rate) is quantitatively analyzed. Finally, the predictive capability of the present model is demon- I NTRODU CTl ONPoly (vinyl chloride ) ( PVC ) is one of the oldest polymers and the second largest in volume thermoplastic manufactured in the world.' The enormous expansion of the PVC industry is due to the high versatility of PVC as a plastic raw material. A review of the qualitative and quantitative aspects of PVC polymerization can be found in reviews by Butters,2 B~r g e s s ,~ R a n~e ,~ and Langsam5 and more recently by Tornell, Xie et al., 7,8 and Yuan et al. ' PVC is effectively insoluble in its own monomer; thus, vinyl chloride monomer (VCM) polymerization is a heterogeneous process that involves several physical transitions during the polymerization. As a result, the final particulate product is made up of primary particles and its aggregates. The nucleation,

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Section: Ntrodu Ctl Onmentioning

confidence: 99%

Section: Calculation Of the Coalescence Rate Constantmentioning

confidence: 99%

Dynamic simulation of primary particle‐size distribution in vinyl chloride polymerization

Kiparissides

Achilias

Chatzi

1994

J of Applied Polymer Sci

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“…Ormondroyd [86] demonstrated the effect of PVA structure on the particle size, cold plasticizer absorption, and bulk density of the PVC produced. The mechanism by which such SSAs function is not entirely clear [80,[90][91][92]. Cebollada et al [81] showed how HPMC structure and concentration influenced the particle properties of PVC.…”

Section: Events At High Monomer Conversion 231mentioning

confidence: 99%

Free‐Radical Polymerization: Suspension

Brooks¹

2005

Handbook of Polymer Reaction Engineering

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“…Several papers have been published with regard to modeling sustained oscillations in steady state of continuous emulsion polymerizations [4,6,12,[18][19][20][21][22][23][24][25][26]. Four papers are known dealing with dynamic modeling of continuous emulsion polymerization of vinyl chloride.…”

Section: Modeling Of Sustained Oscillationsmentioning

confidence: 99%

Modeling sustained oscillations in continuous emulsion polymerization of vinyl chloride

Tauer

Müller

1993

Acta Polymerica

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A simple mathematical model for the continuous emulsion polymerization of vinyl chloride based on nonlinear ordinary differential equations for the variation of particle concentration, total particle volume, and water-soluble oligomeric products was developed and used to investigate which reactions influence whether or not sustained oscillations of latex properties occur at high conversion steady state. Results of the calculations are in good qualitative agreement with experimental data. Specifically, numerical analysis showed that the occurrence of sustained oscillations depends on particle coalescence as well as on the conversion dependence ofboth particle volume growth rate and particle coalescence rate. The model makes it possible to calculate the dynamic behavior of continuous emulsion polymerization reactors with regard to latex properties such as particle concentration, mean particle size, latex surface tension, solid content, and degree of coverage of latex surface with emulsifier from the start-up into a high conversion steady state.

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Electrostatic and steric stabilization of PVC primary particles

Cited by 17 publications

References 26 publications

Dynamic simulation of primary particle‐size distribution in vinyl chloride polymerization

Dynamic simulation of primary particle‐size distribution in vinyl chloride polymerization

Free‐Radical Polymerization: Suspension

Modeling sustained oscillations in continuous emulsion polymerization of vinyl chloride

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