Diffusion phenomenon of solvent molecules within the polymeric coatings has a great influence on their properties. To study this phenomenon, a new semi-empirical model was developed using the combination of a theoretical model proposed based on the Fick’s second law of diffusion with the empirical technique of coating capacitance measurement. The proposed model has both a simple form and high ability to deal with the diffusion behavior over the whole of immersion time. Additionally, the parameters of the diffusion coefficient and the type (Fickian or non-Fickian) were precisely calculated by fitting of the proposed model to the literature experimental data. According to this modeling approach, the diffusion coefficient has no constant value and reduces over the immersion time.

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