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TAV, CUMALİ

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TAV

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CUMALİ

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End date: 2009 × Start date: 2005 ×

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    Linking the viscous and vacancy behavior of mixtures of high-molecular-weight hydrocarbons
    (SPRINGER/PLENUM PUBLISHERS, 2006) TAV, CUMALİ; Sahin, F.; Tav, C.; Yahsi, U.
    A zero-shear viscosity model has now been extended to mixtures of three-branch alkanes with and without cyclopentyl or cyclohexyl attachments. The model links the equilibrium theory of Simha-Somcynsky (SS) statistical thermodynamics of liquids and the Eyring significant structure (ESS) transport theory. The predicted quantity of the hole fraction as a measure of the free volume, computed from the SS equation of state, plays a primary role in the approach to combine both theories. Experimental PVT eta data from 310 to 408 K and 0.1 to 344.5 MPa have been used. The proportionality constant of the activation energy and the transmission coefficient have been calculated for each species separately, and they are in the expected trend with the fraction of mixtures. Satisfactory agreement in the prediction of viscosity from the hole fraction has been obtained. The volumetric and viscous data of physical mixtures are predicted from and compared with their chemical correspondence.
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    On the Ionic Conductivity of Polymer Electrolytes in Terms of Hole Fraction
    (JOHN WILEY & SONS INC, 2008) TAV, CUMALİ; Yahsi, Ugur; Ulutas, Kemal; Tav, Cumali; Deger, Deniz
    A theoretical model to interpret the conductivity of ions through polymer electrolytes is established in terms of the temperature and pressure-dependent hole fraction computed from Simha-Somcynsky hole theory. The model successfully linearizes the logarithm of PPG and PEG conductivity data with NaCF3SO3 in a 20:1 ratio for a broad range of temperature and pressure. The conductivity parameter and transmission coefficient with an additive hole fraction constant are discussed and compared for both species. The derivative of the logarithm of conductivity with respect to the hole fraction decreases inversely with the hole fraction and saturates at about 0.08 and 0.12 hole fractions for PPG and PEG, respectively. (C) 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2249-2254, 2008
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    A method for obtaining the pure annihilation peak of Na-22 radioisotope
    (PERGAMON-ELSEVIER SCIENCE LTD, 2005) TAV, CUMALİ; Celiktas, C; Tav, C
    By means of pulse separation technique, the annihilation gamma ray peak, which has great importance for positron annihilation lifetime spectroscopy (PALS), was discriminated from the superimposed photon spectrum generated by Compton effect, backscattering, and background in the 0.5 MeV energy region. Energy resolution of 4.5% was obtained for the discriminated annihilation peak of Na-22 positron emitter radioisotope. (c) 2004 Elsevier Ltd. All rights reserved.