Person: MADAKBAŞ, SEYFULLAH
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MADAKBAŞ
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SEYFULLAH
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Publication Metadata only Effects of boron nitrite in thermoplastic polyurethane on thermal, electrical and free volume properties(SPRINGER, 2019) TAV, CUMALİ; Dumludag, Fatih; Yener, Murat Y.; Basturk, Emre; Madakbas, Seyfullah; Kahraman, Vezir; Umer, Muhammad A.; Yahsi, Ugur; Tav, CumaliThe effects of various filler amounts of boron nitride (BN) on surface morphology, DC and AC conductivity and free volume properties of thermoplastic polyurethane (TPU) were investigated using FTIR, TGA, DSC, SEM, PALS and conductivity (DC and AC) measurements. The free volume properties, electrical measurements and surface morphology of TPU/BN were found to be dependent on temperature and weight percentages of BN content. When one weight percentage of BN was added in TPU, the glass transition temperature jumped to 69.42 degrees C from -1 degrees C. Increasing BN weight percentages caused the glass transition temperature of the TPU/BN composites to decrease slightly. Morphological measurements indicated that agglomerations occurring throughout the TPU/BN composites did not cause remarkable effects on their thermal stabilities. Orthopositronium lifetime (or free volume) and intensity increased significantly as a function of temperature, but with respect to BN weight percentages in TPU, they showed a peak with a highest value at about 2% BN content. Similarly, DC and AC conductivity measurements were carried out on TPU with and without BN content at temperatures ranging from 23 to 105 degrees C in dark under vacuum and in the frequency range of 40Hz-100kHz. The DC and AC conductivity values with increasing BN weight percentages showed the similar behavior as free volume fraction that had a peak at about 2% BN content.Publication Metadata only Thermal and dielectric properties of flexible polyimide nanocomposites with functionalized nanodiamond and silver nanoparticles(2023-05-01) BİRTANE, HATİCE; MADAKBAŞ, SEYFULLAH; ESMER, KADİR; KAHRAMAN, MEMET VEZİR; Birtane H., Cigil A. B., Madakbaş S., Esmer K., Kahraman M. V.In the present study, amine groups were first modified to diamond and silver nanoparticles using APTMS to improve their homogeneous dispersion and compatibility in polyamic acid. Flexible polyimide nanocomposite films were successfully prepared by adding modified nanodiamond and silver nanoparticles to 4,4 \"-(1,3-phenylenedioxy) dianiline and benzophenone-3,3 \",4,4 \"-tetracarboxylic dianhydrides with different proportions. The effects of added amine-modified nanoparticles on dielectric constant and thermal stability were investigated. With SEM analysis, nanoparticles were homogeneously distributed on the polyimide surface and the presence of Si atom resulting from APTMS modification is clearly seen with the SEM-EDAX results. Considering the thermal resistance, the maximum decomposition temperature of the nano particle-free PI film was found to be 501 degrees C, while the thermal decomposition temperatures of the PI nanocomposite film that contains 1% m-Ag and the PI film that contains 5% m-ND, 502 degrees C and 505 degrees C, respectively. Also, it was seen that the dielectric constants of the prepared nanocomposite films that contain m-Ag NP decrease with increasing m-Ag NP ratio, and the dielectric constants of the films that contain m-ND increase with increasing m-ND ratio.Publication Metadata only Preparation, characterisation, and dielectric properties of polypyrrole-clay composites(SPRINGER INTERNATIONAL PUBLISHING AG, 2013) ÇAKMAKÇI, EMRAH; Madakbas, Seyfullah; Cakmakci, Emrah; Kahraman, Memet Vezir; Esmer, KadirIn this study, polypyrrole-clay (PPy-clay) composites were prepared by the in situ chemical oxidative polymerisation of pyrrole in the presence of clay. The chemical structures of the composites were characterised by FTIR and XRD analysis. The thermal properties of these novel composites were analysed by TGA and DSC measurements. Glass-transition temperatures and char yields increased with the increase in clay content in the nanocomposites. The interactions between PPy and clay were mainly between polypyrrole and the layers of clay. It was observed that, as the amount of clay in the composites increased, the dielectric permittivity decreased while the dielectric conductivity of the composite materials increased.Publication Metadata only Preparation, Characterization, Thermal, and Dielectric Properties of Polypyrrole/h-BN Nanocomposites(WILEY-HINDAWI, 2014) DUMLUDAĞ, FATİH; Madakbas, Seyfullah; Sen, Ferhat; Kahraman, Memet Vezir; Dumludag, FatihThe aim of this study was to improve thermal stability and dielectric properties of polypyrrole (PPy) by adding hexagonal boron nitride (h-BN). PPy was synthesized, and PPy/h-BN nanocomposites were prepared by adding various proportions of h-BN to PPy. The chemical structures of the samples were investigated by Fourier transform infrared spectroscopy. Thermal properties of the nanocomposites were determined by thermogravimetric analysis and differential scanning calorimetry. X-ray diffraction analysis of the samples was carried out. The surface morphologies of the samples were investigated by a scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The obtained results prove that the nanocomposite system is more thermally stable than the pure PPy. Dielectric measurements revealed that the dielectric constant of the pellets increased with increasing temperature and decreased with increasing frequency. It is also observed that the dielectric constant of the pellets decreased with increasing nano-hBN content (between 1 and 4 wt%).