Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

Browse

Filters

Settings

Publication Index: search.filters.publicationIndex.ScopusSubject: search.filters.subject.Dispersions

Search Results

Now showing 1 - 4 of 4
  • Article
    Citation - Scopus: 1
    Production and Dispersion of Plasma Functionalized Carbon Nanotubes in Pan Fiber Spinning Solution With Different Surfactants
    (MMOB Tekstil Mühendisleri Odası, 2022) Kutlu, Bengi; Akşit, Aysun; Özyüzer, Lütfi; Yağmurcukardeş, Nesli; Selamet, Yusuf
    In this study, the distribution of plasma-functionalized multi-walled carbon nanotubes in polyacrylonitrile nanocomposite fibers produced by wet spinning method using different surfactants (Triton-X and sodium dodecyl sulfate) was investigated. Firstly, we produced CNTs by chemical vapor deposition (CVD) technique. Secondly, low-pressure plasma functionalization of CNTs was realized. Finally, nanocomposite polyacrylonitrile fibers doped by CNTs were obtained using wet spinning technique. Properties of produced carbon nanotubes, functionalized carbon nanotubes and nanocomposite polyacrylonitrile fibers were examined by the analyses of chemical composition, surface structure, structural and mechanical properties.
  • Article
    Citation - WoS: 20
    Citation - Scopus: 20
    Effect of Pore To Throat Size Ratio on Thermal Dispersion in Porous Media
    (Elsevier Ltd., 2016) Özgümüş, Türküler; Mobedi, Moghtada
    In this study, the effects of pore to throat size ratio on thermal dispersion of periodic porous media consisting of inline array of rectangular rods are investigated, numerically. The continuity, momentum and energy equations are solved for representative elementary volumes (REVs) of the porous media to obtain microscopic velocities in the voids between the rods and temperature distribution for entire of the REVs. Volume averaging method is employed to compute the macroscopic velocity and temperature values. There are velocity and temperature deviations between the macroscopic and microscopic values. These deviations are computed numerically and thermal dispersion coefficients of the porous media are determined. The aim of this study is to analyze the effects of pore to throat size ratio on the longitudinal and transverse thermal dispersion in the porous media. The study is performed for pore to throat size ratios between 1.63 and 7.46, porosities from 0.7 to 0.9, and pore level Reynolds numbers between 1 and 100. It is found that in addition to the porosity and Reynolds number, the parameter of pore to throat size ratio plays an important role on thermal dispersion in a porous medium. It is found that there is an optimum value of pore to throat size ratio for maximum longitudinal thermal dispersion coefficient; however, the transverse thermal dispersion increases with the increasing of values of pore to throat size ratio.
  • Conference Object
    Effect of Peo/Ppo Type Triblock Copolymers on Dispersion Behaviour of Aqueous Alumina Suspensions
    (Trans Tech Publications, 2001) Şakar, Aylin M.; Polat, Hürriyet; Çiftçioğlu, Muhsin
    The aim of this study was to investigate the stability and dispersion behaviour of aqueous alumina suspensions in the presence of polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO/PPO/PEO) type block copolymers. The influence of water soluble triblock copolymers with molecular weight ranging from 2900 to 12600 g/mole were tested at Φ = 0.125, 1, 10, 20 vol % solid loading alumina suspensions by rheological, turbidity, sedimentation and surface tension measurements. The results indicate that an alternative dispersant for alumina suspensions is the PEO/PPO triblock copolymers. Their stabilisation mechanism was attributed to the depletion stabilisation. Rheological measurements indicated that these block copolymers (at high EO percentages) coupled with ultrasonic treatment have a positive effect on the dispersion of the agglomerated alumina suspensions. It was not possible to create stable dispersions in the absence of ultrasonic bath treatment. Turbidity measurements at Φ = 0.025, 0.125 vol % showed that, alumina suspensions with PEO/PPO added were stable and have higher turbidity values than block copolymer free suspensions.
  • Article
    Citation - WoS: 21
    Citation - Scopus: 24
    Kinetics of Oil Dispersion in the Absence and Presence of Block Copolymers
    (John Wiley and Sons Inc., 1999) Polat, Hürriyet; Polat, Mehmet; Chander, Subhash
    A phenomenological model proposed describes droplet breakup in the turbitlently agitated lean oil-in-water dispersions and provides a correlation between the median droplet size in an agitated vessel of standard geometry and the time of dispersion. It was assumed that the droplet breakup takes place in the dispersion-only region and coalescence is negligible. Vie model described the data from this study and the literature quite satisfactorily under these conditions. The effect of adding triblock PEO/PPO/PEO copofymeric surfactants on the dispersion kinetics of oil was also investigated. Addition of surfactant reduced the median oil droplet size significanfty, and the extent of this reduction was a strong function of surfactant concentration. Application of the model on these data demonstrated that the change in the median droplet size could be divided into two distinct regions. The breakage rate was high initially, most probably due to continuous adsorption of surfactant molecules at the oil/water interface. A lower breakage rate was attained at longer tunes, as the surfactant molecules were depleted from the solution. The time of transition bet\veen the t\vo was affected strongly by the concentration of the surfactant added. Furthermore, the time of addition of the surfactant did not affect the final droplet-size distribution in the system.