Modelling prediction of the microcapsule size of polyelectrolyte complexes produced by atomization

In order to have a better understanding of the atomization process for microencapsulation applications the disintegration of polymer liquid jets (sodium alginate) injected into high-velocity gas streams was studied and a mathematical model to predict the microparticle size has been developed. Air-blast atomization of viscous non-Newtonian fluid (alginate solution) was carried out in order to produce microbeads (1-50 mu m) based on polyelectrolyte complexes with particle size control and a particle size distribution with a relative span factor, (D-0.9 - D-0.1)/D-0.5, less than 1.4. The accuracy of the wave-mechanisms-based models in predicting droplet size after breakup of alginate solution has been demonstrated. The atomized microparticle size were expressed in terms of three dimensionless groups, the liquid/air mass ratio, the Weber number and the Ohnesorge number in simple forms whose exponents and coefficients were determined by least-squares fit to the experimental data. With these data two semi-empirical models have been proposed to predict the particle size obtained from the microencapsulation. Both models allow the prediction of particle size of the microcapsules obtained by atomization processes. (c) 2006 Elsevier B.V All rights reserved.