Non-Fickian Drying of Polymeric Coatings

Concentration profiles in two binary polymeric coatings - poly (styrene)- p-xylene and poly (methyl methacrylate) - ethylbenzene, have been measured using confocal laser Raman spectroscopy. Measured profiles are very different from as shown earlier for rubbery coatings. Sigmoidal profiles are observed in these polymeric coatings during the course of drying because they went through the glass transition temperature. Fick's law of diffusion is inadequate to explain such type of diffusion.