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MADAKBAŞ, SEYFULLAH

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MADAKBAŞ

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2014 - 20192
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Author: DUMLUDAĞ, FATİH × Subject: CONDUCTIVITY ×

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    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, Cumali
    The 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.
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    Preparation, Characterization, Thermal, and Dielectric Properties of Polypyrrole/h-BN Nanocomposites
    (WILEY-HINDAWI, 2014) DUMLUDAĞ, FATİH; Madakbas, Seyfullah; Sen, Ferhat; Kahraman, Memet Vezir; Dumludag, Fatih
    The 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%).