Kinetics of Polycondensation in a Spray of Aqueous and Aqueous-Alcoholic Solutions of Lactic Acid

An advantage of spray technologies in polycondensation processes is the efficient removal of low-molecular-weight products and heat. These advantages are based on dimensional effects which may lead a substantial shift of chemical equilibrium in reversible reactions. In this work, within the framework of formal chemical kinetics, the authors have modeled the dependence of the polycondensation rate on the droplet size, the composition of the reactive mixture, and the gas medium. This dependence was reproduced experimentally using the polycondensation of lactic acid as an example. Based on the results of microscopic observation of the behavior of an ensemble of sessile droplets of aqueous and aqueous-alcoholic solutions of lactic acid, the authors have constructed kinetic curves of contraction of droplets of varying size. The contraction is a result of the set of interrelated external and intradiffusion and intrakinetic processes and phase transformations whose limiting stage is the polymerization rate. The described regularities are thermodynamic in nature and must be manifested in polymerization and polycondensation with the participation of volatile monomers and solvents.