Chemistry / Kimya

Permanent URI for this collectionhttps://hdl.handle.net/11147/4072

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2010 - 20112

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  • Article
    Citation - WoS: 36
    Citation - Scopus: 38
    Investigation on Glassy Skin Formation of Porous Polystyrene Fibers Electrospun From Dmf
    (BME-PT, 2010) Demir, Mustafa Muammer
    Micrometer and submicrometer diameter of polystyrene (PS) fibers were electrospun from various dimethyl formamide (DMF) solutions at different weight fractions under 35% relative humidity. Increasing polymer fraction in the solution results in a gradual morphological transition from beads-with-incipient to bead-free fibers and also increases the diameter. The formation of uniform glassy skin presumably due to radial capillary flow within the liquid jet was confirmed by scanning electron microscope. The thickness of the skin varies with the weight fraction of PS; therefore, it was normalized with respect to average fiber diameter (AFD). The skin gets thinner as the weight fraction of PS increases. In addition, the fibers exhibit highly porous internal structure and smooth surface along with slight porosity. The development of porosity is attributed to liquid-liquid phase separation of water molecules in atmospheric moisture and DMF.
  • Article
    Citation - WoS: 74
    Humidity Sensing Properties of Zno-Based Fibers by Electrospinning
    (Elsevier Ltd., 2011) Horzum Polat, Nesrin; Taşçıoğlu, Didem; Okur, Salih; Demir, Mustafa Muammer
    Zinc oxide (ZnO) based fibers with a diameter of 80-100 nm were prepared by electrospinning. Polyvinyl alcohol (PVA) and zinc acetate dihydrate were dissolved in water and the polymer/salt solution was electrospun at 2.5 kV cm-1. The resulting electrospun fibers were subjected to calcination at 500 °C for 2 h to obtain ZnO-based fibers. Humidity sensing properties of the fiber mats were investigated by quartz crystal microbalance (QCM) method and electrical measurements. The adsorption kinetics under constant relative humidity (RH) between 10% and 90% were explained using Langmuir adsorption model. Results of the measurements showed that ZnO-based fibers were found to be promising candidate for humidity sensing applications at room temperature.