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GÜLLÜOĞLU, ARİF NİHAT

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GÜLLÜOĞLU

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ARİF NİHAT

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2008 - 20102
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    Dielectric properties of polymer composites filled with different metals
    (TAYLOR & FRANCIS INC, 2008) GÜLLÜOĞLU, ARİF NİHAT; Qureshi, Anjum; Mergen, Ayhan; Eroglu, Mehmet S.; Singh, N. L.; Gulluoglu, Arif
    Electrically conductive composite systems based on polyvinyl chloride (PVC) and polymethyl methacrylate (PMMA) filled with metal powders of Al and Cu have been studied. The composite preparation conditions allow the formation of a random distribution of metallic particles in the polymer matrix. Dependence of the dielectric and conductivity properties of the PVC and PMMA/fillers was studied over a broad range of frequency and volume fraction of metal fillers. The experimental results could be explained by means of the conductivity of fillers and the interface polarization between polymers and fillers. Percolation was also seen in this study when the volume fraction of conducting fillers was close to critical value, in which the composites undergo an insulator-conductor transition. The relation among the dielectric property and the fillers with different conductivity was proposed.
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    Radiation induced modification of dielectric and structural properties of Cu/PMMA polymer composites
    (ELSEVIER SCIENCE BV, 2010) GÜLLÜOĞLU, ARİF NİHAT; Singh, Dolly; Singh, N. L.; Qureshi, Anjum; Kulriya, P.; Tripathi, Ambuj; Avasthi, D. K.; Gulluoglu, Arif N.
    In this study, composite films consisting of an insulating polymethyl methacrylate (PMMA) polymer matrix and metal powder (Cu) additive were prepared by solution costing method. These films were irradiated with 140 MeV silver ions at the fluences of 1 x 10(11) ions/cm(2) and 1 x 10(12) ions/cm2. The radiation induced changes in dielectric, structural and surface properties of PMMA/Cu composites were studied using impedance/gain phase-analyzer, X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). It was observed that the dielectric properties and ac electrical conductivity increased significantly with the concentration of dispersed metal powder (Cu) and also with the fluence. This reveals that ion beam irradiation creates free radicals, unsaturation etc. due to emission of hydrogen and/or other volatile gases, which makes the polymer more conductive. XRD analysis of the pristine and irradiated samples shows that the crystallinity improved upon irradiation at low fluence and deteriorated on further increase of the fluence, which could be attributed to cross linking of polymer chains at low fluence and degradation at higher fluence. High energy ion beam irradiation of semicrystalline polymer composite films changes its Tg behavior as observed from DSC analysis. This result is also corroborated with the results of XRD. The average surface roughness and topography of surfaces changed with the concentration of filler and also with the ion fluence as revealed from AFM/SEM analysis. (C) 2010 Elsevier B.V. All rights reserved.