Modeling of the particle size distribution in emulsion polymerization

Abstract

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.

Modelling of Butyl Acrylate Emulsion Polymerisation: A Detailed Lumped Parameter Approach

“…The other details in Models 1 and 2 were the same. Thus, in both the models i = 0.05 and the aqueous phase radical concentration [R] was given by Equation (21). Only micellar nucleation was considered.…”

“…The important ones are nucleation in monomer-swollen micelles, nucleation in the aqueous phase or homogeneous nucleation and coagulative nucleation. A review of these mechanisms can be found elsewhere [21]. Sood and Lodhi [16] considered all these three mechanisms in their work and the same treatment was considered in this work also.…”

“…Here, collisional radical entry model is used as has been done in our previous works [4,5,16,20,21].…”

“…We considered Equation (21) for radical concentration for micellar entry. For radical entry in particles, we considered both Equations (21) and (23), one by one.…”

A Lumped Model for Butyl Acrylate Emulsion Polymerization

“…The values of various parameters used in the simulation are given in Table 1 and were taken from the works of Coen et al [2] and Sood [12]. In addition to these parameters, there are expressions describing events such as radical entry into the particles.…”