A model capable of predicting the release of an Active Ingredient (AI) from a specific device would be very useful in the field of pesticide controlled release technology for design purposes. For the release of an AI from a microcapsule a mathematical model is briefly presented here, as an introduction to the principal objective of this work, which is the prediction of the model parameters (diffusion and partition coefficients). In particular, this paper focuses on the estimation of the partition coefficient of the AI in the polymer through activity coefficients, that are estimated with a group-contribution model for polymers (GC-Flory EoS). Therefore, this model (GC-Flory EoS) is extended in order to suit the needs of the complex pesticide molecules. The results of the extension of the GC-Flory EoS model, together with a case study dealing with the release of a pesticide from a microcapsule as well as the estimation of model parameters are presented. (c) 2004 Elsevier B.V. All rights reserved.
Fluid Phase Equilibria, 2005, Vol 228-229, Issue SI, p. 127-133