Browsing by Author "Ugur, Saziye"

Filter results by typing the first few letters
Now showing 1 - 5 of 5
  • Thumbnail Image
    Article
    Citation Count: 4
    Diffusion energies of oxygen diffusing into polystyrene (PS)/poly (N-isopropylacrylamide) composites
    (Wiley-Blackwell, 2012) Yargı, Önder; Ugur, Saziye; Pekcan, Önder
    Diffusion coefficient of oxygen penetrating into polystyrene (PS) latex/poly (N-isopropylacrylamide) (PNIPAM) microgel composite films were measured using Fluorescence technique. Three different (5 15 and 40wt%) PS content films were prepared from PS/PNIPAM mixtures. Diffusivity of PS/PNIPAM composite films were studied by diffusion measurements which were performed over the temperature range of 24-70 degrees C. Pyrene was used as the fluorescent probe. The diffusion coefficients (D) of oxygen were determined using the SternVolmer fluorescence quenching method combined with Fickian transport and were computed as a function of temperature for each PS content film. The results showed that D values were strongly dependent on both temperature and PS content in the film. Diffusion energies were measured and found to be dependent on the composition of the composite films. Copyright (C) 2011 John Wiley & Sons Ltd.
  • Thumbnail Image
    Article
    Citation Count: 3
    The effect of film thickness and TiO2 content on film formation from PS/TiO2 nanocomposites prepared by dip-coating method
    (Hindawi Publishing Corporation, 2012) Sunay, M. Selin; Pekcan, Önder; Ugur, Saziye
    Steady-state fluorescence (SSF) technique in conjunction with UV-visible (UVV) technique and atomic force microscope (AFM) was used for studying film formation from TiO2 covered nanosized polystyrene (PS) latex particles (320 nm). The effects of film thickness and TiO2 content on the film formation and structure properties of PS/TiO2 composites were studied. For this purpose two different sets of PS films with thicknesses of 5 and 20 mu m were prepared from pyrene-(P-) labeled PS particles and covered with various layers of TiO2 using dip-coating method. These films were then annealed at elevated temperatures above glass transition temperature (T-g) of PS in the range of 100-280 degrees C. Fluorescence emission intensity I-p from P and transmitted light intensity I-tr were measured after each annealing step to monitor the stages of film formation. The results showed that film formation from PS latexes occurs on the top surface of PS/TiO2 composites and thus developed independent of TiO2 content for both film sets. But the surface morphology of the films was found to vary with both TiO2 content and film thickness. After removal of PS thin films provide a quite ordered porous structure while thick films showed nonporous structure.
  • Thumbnail Image
    Article
    Citation Count: 0
    Fluorescence Study of Film Formation from PS Latex-TiO2 Composites: Effects of TiO2 Content Film Thickness and Particle Size
    (Amer Scientific Publishers, 2015) Ugur, Saziye; Sunay, M. Selin; Pekcan, Önder
    Steady-state fluorescence (SSF) technique in conjunction with UV-visible (UVV) technique atomic force microscope (AFM) and scanning electron microscope (SEM) is used for studying film formation from TiO2 covered polystyrene (PS) latex particles. The effects of TiO2 content film thickness and PS particle size on film formation and structure properties of PS/TiO2 composites are studied. For this purpose in the first part two different sets of PS films with thicknesses of 5 and 20 mu m were prepared from pyrene-(P-) labeled PS particles (320 nm) and covered with various layers of TiO2 with the use of dip-coating method. These films were then annealed at elevated temperatures above glass transition temperature (T-g) of PS in the range of 100-280 degrees C. Fluorescence emission intensity I-p from P and transmitted light intensity I-tr were measured after each annealing step to monitor the stages of film formation. The results show that film formation from PS latexes occurs on the top surface of PS/TiO2 composites and thus develop independent from TiO2 content for both film sets. However the surface morphology of the films was found to vary with both TiO2 content and film thickness. After removal of PS thin films provide a quite ordered porous structure while thick films show nonporous structure. In the second Part two film series were prepared from PS particles with diameters of 203 nm (SmPS) and 382 nm (LgPS) covered with different layers of TiO2 and annealed at elevated temperatures. Results reveal that SmPS/TiO2 films undergo complete film formation independent of the TiO2 content. However no film formation occurs above a certain TiO2 content in LgPS/TiO2 films. SEM images demonstrate that SmPS/TiO2 films have highly well-ordered microporous structures with increasing TiO2 content after extraction of PS polymer whereas LgPS/TiO2 composites show no porous structure for high TiO2 content. Our experiments also show that porous TiO2 films with different sizes could successfully be prepared with this technique.
  • Thumbnail Image
    Article
    Citation Count: 6
    Oxygen Diffusion into Multiwalled Carbon Nanotube Doped Polystrene Latex Films Using Fluorescence Technique
    (Springer/Plenum Publishers, 2013) Yargı, Önder; Ugur, Saziye; Pekcan, Önder
    This study examines the oxygen diffusion into polystyrene (PS) latex/multiwalled carbon nanotube (MWNT) nanocomposite films (PS/MWNT) consisting of various amounts of MWNT via steady state fluorescence technique (SSF). PS/MWNT films were prepared from the mixture of MWNT and pyrene (P)-labeled PS latexes at various compositions at room temperature. These films were then annealed at 170 A degrees C above glass transition (T-g) temperature of PS. Fluorescence quenching measurements were performed for each film separately to evaluate the effect of MWNT content on oxygen diffusion. The Stern-Volmer equation for fluorescence quenching is combined with Fick's law for diffusion to derive the mathematical expressions. Diffusion coefficients (D) were produced and found to be increased from 1.1 x 10(-12) to 41 x 10(-12) cm(2)s(-1) with increasing MWNT content. This increase was explained via the existence of large amounts of pores in composite films which facilitate oxygen penetration into the structure.
  • Thumbnail Image
    Article
    Citation Count: 4
    Spectroscopic study of film formation from polystyrene latex/TiO2 nanocomposites prepared by dip-coating method
    (Wiley-Blackwell, 2014) Sunay, M. Selin; Pekcan, Önder; Rahman, Md. Mahbubor; Elaissari, Abdelhamid; Ugur, Saziye
    In this study we investigated the influence of TiO2 content and thickness of polystyrene (PS) template on film-formation behavior of PS/TiO2 composites using fluorescence and ultraviolet-visible techniques in conjunction with scanning electron microscopy. Films were prepared by coating PS templates with various layers of TiO2 using dip-coating method. The results showed that PS latexes present complete film formation on top surface of composites. After extraction of PS a well-defined interconnected porosity were obtained for thin films when TiO2 content was increased whereas thick samples did not present any interconnected porous structures above a certain TiO2 layer. POLYM. ENG. SCI. 54:288-302 2014. (c) 2013 Society of Plastics Engineers