Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 26Citation - Scopus: 27Understanding the Effect of Skin Formation on the Removal of Solvents From Semicrystalline Polymers(John Wiley and Sons Inc., 2005) Wong, Sim-Siong; Alsoy Altınkaya, Sacide; Mallapragada, Surya K.The effect of glassy skin formation on the drying of semicrystalline polymers was investigated with a comprehensive mathematical model developed for multicomponent systems. Polymers with high glass-transition temperatures can become rubbery at room temperature under the influence of solvents. As the solvents are removed from the polymer, a glassy skin can form and continue to develop. The model takes into account the effects of diffusion-induced polymer crystallization as well as glassy-rubbery transitions on the overall solvent content and polymer crystallinity. A Vrentas-Duda free-volume-based diffusion scheme and crystallization kinetics were used in our model. The polymer-solvent system chosen was a poly(vinyl alcohol) (PVA)-water-methanol system. The drying kinetics of PVA films were obtained by gravimetric methods with swollen films with known water/methanol concentrations. The overall drying behaviors of the polymer system determined by our model and experimental methods were compared and found to match well.Article Citation - WoS: 46Citation - Scopus: 48Drying of Semicrystalline Polymers: Mathematical Modeling and Experimental Characterization of Poly(vinyl Alcohol) Films(Elsevier Ltd., 2004) Wong, Sim-Siong; Alsoy Altınkaya, Sacide; Mallapragada, Surya K.A mathematical model was developed to predict the drying mechanism of semicrystalline polymers involving multiple solvents. Since drying of semicrystalline polymers can be accompanied by changes in polymer degree of crystallinity, the model integrates crystallization kinetics and the Vrentas-Duda diffusion model to provide a better understanding of the mechanism. The model considers the effect of external conditions such as temperature, film shrinkage and diffusion and evaporation of multiple solvents during drying. Poly(vinyl alcohol) (PVA)/water/methanol was chosen as a test system. The drying kinetics of PVA films swollen in water and methanol were investigated using gravimetric techniques. The model predicts that higher temperatures, lower film thicknesses and lower methanol to water ratios increase the drying rate. The model predictions were compared with experimental data and showed good agreement.