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 Preparation and electrical properties of polypyrrole containing photocured thiol-ene based composites(ELSEVIER SCIENCE SA, 2015) DUMLUDAĞ, FATİH; Madakbas, Seyfullah; Dumludag, Fatih; Eminoglu, Elif Merve; Sen, Ferhat; Kahraman, Memet VezirIn this study, UV curable polypyrrole containing thiol ene based composite films were prepared by the reaction between Propoxylated (2) neopentyl glycol diacrylate (SR 9003), Trimethylolpropane tris(3-mercaptopropionate), (3-mercaptopropyl)trimethoxysilane, 1-vinyl-2-pyrrolidinone and polypyrrole. FT-IR was used to confirm the formation of the composites. Thermal stability of the samples was evaluated by thermogravimetric analysis (TGA). The samples were characterized with the following analysis; gel content, water absorption capacity. Hydrophobicity of the samples was determined by the contact angle measurements. Direct current (dc) conductivity measurements of samples were performed depending on polypyrrole content in the composites at room temperature. Capacitance measurements (40 Hz-100 kHz) of the samples were performed in the temperature range of 295-378 K. Dc conductivity and capacitance values of the samples were measured in vacuum in dark. Dc conductivity measurements revealed that dc conductivity values increased with increasing polypyrrole content. Dielectric measurements revealed that dielectric constant of the samples increased with increasing temperature and decreased with increasing frequency. It is also observed that dielectric constant of the samples decreased with increasing polypyrrole content. (C) 2014 Elsevier B.V. All rights reserved.Publication Metadata only Preparation, characterization and electrical properties of polyacrylonitrile/huntite composites(SPRINGER, 2014) DUMLUDAĞ, FATİH; Madakbas, Seyfullah; Celik, Zeynep; Dumludag, Fatih; Kahraman, Memet VezirWe focused on polyacrylonitrile (PAN)/huntite composites to reinforce the polymer prepared by adding different percentages (wt%) of huntite to PAN. The composites were characterized using thermogravimetric analysis, differential scanning calorimetry, fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy techniques. It was clearly seen that the composites of PAN/huntite have better thermal stability than pure PAN. The effect of the huntite adding to Polyacrylonitrile (PAN) on dc conductivity and dielectric constant was also investigated. Dc conductivity values were increased with increasing temperature. Activation energy values were calculated depending on huntite contents in PAN. Relative dielectric constant values varied in the range of 16.5-21.2 at room temperature at 100 kHz frequency depending on huntite concentrations. All the electrical measurements were performed in dark and vacuum ambient between the temperatures of 295 and 523 K. Dielectric measurements were performed in the frequency range of 40 Hz-100 kHz.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%).