WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Conference Object Predicting Drying in Solvent-Coated Polymeric Films(American Chemical Society, 2000) Alsoy Altınkaya, Sacide; Duda, John Larry[No abstract available]Article Citation - WoS: 153Citation - Scopus: 192Development of Cellulose Acetate Based Antimicrobial Food Packaging Materials for Controlled Release of Lysozyme(Elsevier Ltd., 2009) Gemili, Seyhun; Yemenicioğlu, Ahmet; Alsoy Altınkaya, SacideAntimicrobial packaging materials were obtained by incorporation of lysozyme into cellulose acetate (CA) films. In order to achieve controlled release of lysozyme, the structure of the films was changed from highly asymmetric and porous to dense by modulating the composition of the initial casting solution. The highest release rate, soluble lysozyme activity and antimicrobial activity were obtained with the film prepared from 5% CA solution including 1.5% lysozyme. Increasing CA content in the casting solution decreased the porosity of the films, hence, reduced the release rate, maximum released lysozyme activities and the antimicrobial activities of the films. In contrast, immobilized lysozyme activities and the tensile strength of the films increased. The incorporation of lysozyme did not cause significant reductions in tensile strength and elongation at break values except in films prepared with 15% CA. This study showed the good potential of asymmetric CA films to achieve controlled release in antimicrobial packaging.Article Citation - WoS: 9Citation - Scopus: 8Measurement of Ternary Polymer/Solvent Equilibrium Data by Vapor-Phase Infrared Spectroscopy(Elsevier Ltd., 2009) Yürekli, Yılmaz; Alsoy Altınkaya, SacideVapor-liquid equilibrium (VLE) data for binary toluene/PVAC, methanol/PVAC and ternary toluene/methanol/PVAC systems have been measured at 100 °C by using vapor-phase infrared spectroscopy. Binary data have been compared with literature data measured by different experimental techniques and agreement between our measurements and others was found to be good. The ternary VLE data indicate that the solubility of methanol in PVAC is not influenced by the presence of toluene, while the solubility of toluene is lowered due to presence of methanol. To predict ternary VLE data, the Entropic free volume and Kannan free volume models and the Flory-Huggins theory were used. The predictive abilities of Flory-Huggins theory and the Kannan free volume model are similar and better than that of the Entropic free volume model.Article Citation - WoS: 11Citation - Scopus: 13Sorption and Diffusion of Water Vapour on Edible Films(Springer Verlag, 2008) Berkün, Didem; Balköse, Devrim; Tıhmınlıoğlu, Funda; Alsoy Altınkaya, SacideTwo types of films consisting of sodium salt of carboxymethyl cellulose (NaCMC) and hydroxypropyl cellulose (HPC) as film forming materials and glycerin as plasticizer were prepared, characterized and their water vapour sorption properties were determined. The water sorption isotherms of the films were measured using a magnetic suspension balance. Results show that diffusion of water vapour in NaCMC based film is faster than that in HPC based films, due to the heterogeneous structure and larger pore dimensions of the NaCMC films.Article Citation - WoS: 8Citation - Scopus: 8The Effects of Urease Immobilization on the Transport Characteristics and Protein Adsorption Capacity of Cellulose Acetate Based Hemodialysis Membranes(Springer Verlag, 2009) Yaşar Mahlıçlı, Filiz; Alsoy Altınkaya, SacideIn this study, cellulose acetate (CA) based hemodialysis membranes were prepared by a dry phase inversion method and the influences of urease immobilization on the clearing performance and protein adsorption capacity of the membranes were investigated. Permeation experiments have shown that modification of CA membranes with urease immobilization not only enhanced the transport rate of urea but also increased the permeation coefficients of uric acid and creatinine by changing the structure of the membrane. Furthermore, the protein adsorption capacity of the CA membranes decreased. On the other hand, the mechanical strength of the modified CA membrane did not change significantly compared with that of the unmodified one. A mathematical model was derived to determine the rate of mass transfer of urea through modified CA membranes. Model predictions along with the experimental data suggest that urease immobilization can be used as an alternative method in preparing CA based hemodialysis membranes with improved transport characteristics and biocompatibility through reduced protein adsorption capacities.Article Citation - WoS: 18Citation - Scopus: 21Predicting Emission Characteristics of Volatile Organic Compounds From Wet Surface Coatings(Elsevier Ltd., 2009) Alsoy Altınkaya, SacideA mathematical model is developed to describe the emission characteristics of VOCs from homogeneous wet coating materials deposited on impermeable substrates. The model considers mass transfer in the material and in air, boundary layer resistance and the change in the coating thickness with time due to emission of VOC. Key features of the model are incorporation of concentration dependent VOC diffusion coefficients predicted from a physical model and nonlinear equilibrium isotherm at the coating/air interface. The model is applied to predict emission characteristics of MMA from acrylic based surface coatings. In an attempt to investigate the influences of equilibrium isotherm type and diffusion formalism on the predictions, simulations are performed with either constant or concentration dependent diffusivities and linear or nonlinear equilibrium isotherms. The lowest MMA concentration in air is predicted by incorporating the concentration dependent diffusivity and nonlinear equilibrium isotherm. The results suggest that assuming the diffusivity of MMA constant or equilibrium isotherm linear may lead to wrong conclusions about the emission rates from wet coatings. The model is general, fully predictive and can be used to predict emission rates of different VOCs from different coating materials if diffusion and thermodynamic parameters are available.Article Citation - WoS: 17Citation - Scopus: 18Crystallization of Poly(vinyl Alcohol) During Solvent Removal: Infrared Characterization and Mathematical Modeling(John Wiley and Sons Inc., 2007) Wong, Sim-Siong; Alsoy Altınkaya, Sacide; Mallapragada, Surya K.Crystallization of semicrystalline polymer films during drying has a significant effect on the rate of solvent removal. Understanding and controlling the crystallization kinetics is important in controlling residual solvent levels and drying kinetics. The degree of crystallinity of the poly(vinyl alcohol) films during multicomponent drying was investigated using Fourier transform infrared spectroscopy (FTIR). The 1141 cm-1 band is sensitive to the degree of crystallinity of the polymer and the growth of intensity of this band was monitored as drying progressed. The results from the FTIR studies were comparable to the results obtained from differential scanning calorimetry. Studies were conducted to test the effect of initial solvent composition (water-methanol mixture), drying temperature, and polymer molecular weight on the rate of crystallization and the final crystallinity of the films. An increase in initial methanol composition increased the crystallization rate but did not affect the final degree of crystallinity. An increase in drying temperature and decrease in polymer molecular weight increased the rate of crystallization as well as the final degree of crystallinity. Based on the experimental data, rate constants for crystallization kinetics were extracted from our previously developed model based on free volume theory. The experimental data and the simulation results showed good agreement. The ability of the free volume theory to illustrate the crystallization behavior validated the model and improved its capability.Article Citation - WoS: 23Citation - Scopus: 27In Vitro Drug Release Rates From Asymmetric-Membrane Tablet Coatings: Prediction of Phase-Inversion Dynamics(Elsevier Ltd., 2006) Alsoy Altınkaya, Sacide; Yenal, HacerMost of the controlled-release systems developed for drug delivery applications depend on membrane technology. The dense structure of some membranes used in controlled-release systems can excessively prolong the release of drug due to the low permeability of the coating to drug. To increase the drug release rate, asymmetric-membrane tablet coatings were prepared by a phase-inversion technique using cellulose acetate/acetone/water solution. The roles of the composition of the membrane solution and the evaporation condition on the release rate of drug were determined using in vitro dissolution and morphological studies and predicted phase diagrams. Results show that drug release from asymmetric-membrane based tablet coatings is primarily governed by the dynamics of the phase-inversion process with zero-order or near-zero-order release easily achievable. In an attempt to derive an empirical expression for the release rate of drug as a function of composition of the coating solution, a statistical experimental design was used. Good fit of the experimental data by the empirical expression was obtained. In addition, the predictive capability of the model equation was also found to be satisfactory. Analysis of the significance of each term in the expression indicates that the cellulose acetate:acetone ratio has the most significant influence on the release rate of theophylline.Article Citation - WoS: 51Citation - Scopus: 57Characterization of Waterborne Acrylic Based Paint Films and Measurement of Their Water Vapor Permeabilities(Elsevier, 2006) Topçuoğlu, Özge; Alsoy Altınkaya, Sacide; Balköse, DevrimRecently, production of waterborne coatings has increased significantly as a consequence of strict pollution regulations. Waterborne coatings are sensitive to humidity, thus, their barrier properties with respect to permeation of moisture needs to be determined. Among various coating constituents, binder represents the matrix structure and its amount relative to the amounts of pigments and fillers can significantly affect the structure, hence the barrier property of the coating. In this study, waterborne acrylic based paints applied as protective coating on interior and exterior wall of the buildings are studied. The paint samples formulated with four different binder contents by a commercial paint company are used in the experiments. We first determine unknown ingredients of the paint samples using different characterization tools and then investigate the effect of the binder content on the structure of the paint films. In addition, water vapor permeability of the paint films is measured using a permeation cell. Results show that the barrier property of the waterborne acrylic based paint films against humidity decreases with decreased binder content due to uneven distribution of the pigments, consequently, porous structure formation in the films.Article Citation - WoS: 5Citation - Scopus: 5Solvent Sorption in a Polymer-Solvent System - Importance of Swelling and Heat Effects(Elsevier Ltd., 2006) Alsoy Altınkaya, Sacide; Ramesh, Narayan; Duda, John LarrySorption experiments are often conducted in gravimetric sorption columns where several deviations from ideal conditions could potentially occur. For example, heat effects due to solvent sorption, errors introduced due to concentration dependent diffusion coefficients and swelling are unavoidable. In this study, we develop a model to study the importance of the combination of these effects in obtaining diffusion coefficients from sorption experiments. The model is used to explore a wide range of operating conditions and physical parameters.
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