The Effect of the Thickness of a Coating Made of Oxidized Silicon Compounds on the Desorption of Dioctyl Phthalate from Poly(Ethylene Terephthalate) Films

Based on the literature data, a two-factor model has been developed for predicting the rate of the extraction of dioctyl phthalate from a poly(ethylene terephthalate) film with a silica-based protective coating of different thicknesses. Using the proposed approach to developing the model, the process of plasticizer desorption has been divided into two stages, which differs in the rates of transfer of an ingredient. The coating thickness affects both the desorption rate at the first stage and the plasticizer content, the desorption of which results in the transition to the second stage of the process. A numerical solution of the equation has been performed to obtain the dependence of the content of desorbed dioctyl phthalate on the protective coating thickness and on the extractant temperature.