Accurate prediction of shape and size of polyvinyl alcohol beads produced by extrusion dripping

WEIBEL, MARIO IGNACIO; MENGATTO, LUCIANO NICOLÁS; LUNA, JULIO ALBERTO; RINTOUL, IGNACIO

IRANIAN POLYMER JOURNAL

POLYMER RESEARCH CENTER IRAN

Año: 2018 vol. 27 p. 161 - 170

1026-1265

Beads are one of the particulate delivery systems used to achieve protection and/or controlled delivery of different activeingredients or microorganisms. Polyvinyl alcohol is a non-toxic and biodegradable polymer and possesses extensive applicationsas a biomaterial. In the present work, two different strategies were applied for the prediction of shape and size ofpolyvinyl alcohol beads. These beads were obtained by extrusion dripping of a boric acid?polyvinyl alcohol aqueous solutioninto a basic aqueous gelling bath. The shapes and sizes of immature, mature and dry beads were determined using opticalmicroscopy. Two different strategies included statistical and fluid dynamical (mechanistic) models to fit the experimentaldata. The shape of immature and mature beads was found to be dependent on the viscosity of the dripping solution for theformer and the maturation time for the latter. The shape of dry beads was found to be mainly dependent on the particle contractionin the drying process. The size of mature and dried beads was correctly predicted from the operating conditions bymeans of a statistically developed model and from the dripping solution properties by means of a fluid dynamical approach.The optimal conditions for minimal dried bead size were calculated. The obtained mathematical models allow reduction inthe amount of resources and time taken in the initial stages of the development of a novel encapsulated formulation. Themechanistic model may be applied to other polymeric systems once the corresponding parameters have been determinedduring proof-of-concept experiments.