Person: MADAKBAŞ, SEYFULLAH
Loading...
Email Address
Birth Date
Research Projects
Organizational Units
Job Title
Last Name
MADAKBAŞ
First Name
SEYFULLAH
Name
21 results
Search Results
Now showing 1 - 10 of 21
Publication Metadata only Preparation and Thermal Properties of Polyethylene Terephthalate/Huntite-Hydromagnesite Composites(WILEY, 2016) KAHRAMAN, MEMET VEZİR; Basturk, Emre; Madakbas, Seyfullah; Karadogan, Betul; Kahraman, Memet VezirIn this report, it was aimed to the improve thermal stability of polyethylene terephthalate (PET) by adding huntite/hydromagnesite minerale. PET/huntite/hydromagnesite composites were prepared by adding various proportions of huntite/hydromagnesite to PET. The chemical structures of the composites were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. Thermal properties of the composites were determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Glass-transition temperatures and char yields increased with the increase of the huntite/hydromagnesite content in the composites. The surface morphologies of the composites were investigated by a scanning electron microscopy. The obtained results proved that the composite system is more thermally stable than the pure PET itself. (C) 2015 Society of Plastics EngineersPublication 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 Structural and dielectric properties of POSS reinforced polyimide nanocomposites(TAYLOR & FRANCIS INC, 2019) BİRTANE, HATİCE; Birtane, Hatice; Esmer, Kadir; Madakbas, Seyfullah; Kahraman, Memet VezirIn this study, a series of [3-(2-aminoethyl)amino]propyl-heptaisobutyl substituted polyhedral oligomeric silsesquioxane (AHIP) containing polyimide (PI) nanocomposites were successfully prepared. Structural, thermal and electrical properties of the polyimide nanocomposites were studied. The properties of AHIP containing polyimides were compared with those of the neat polyimide films. The surface morphology of the prepared AHIP containing polyimides were determined by using Scanning Electron Microscopy (SEM). The hydrophilic/hydrophobic nature of AHIP/polyimide composites were analyzed by measuring their water contact angles. It was found that the addition of AHIP into the polyimide slightly increased the contact angle values. The incorporation of 5% AHIP to the PI matrix decreased the dielectric constant value of pure PI from 8.6 to 11.7, respectively. Furthermore he dielectric permittivity was changed from 8.6 (neat polyimide) to 5.5 (PI3).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 Polyurethane graphene nanocomposites with self-healing properties by azide-alkyne click reaction(ELSEVIER SCIENCE SA, 2020) OKTAY, BURCU; Akhan, Seda; Oktay, Burcu; Ozdemir, Oguz Kaan; Madakbas, Seyfullah; Apohan, Nilhan KayamanNanocomposites stand out as promising materials in many fields due to their properties such as strength, hardness, thermal stability, and lightness. Introducing self-healing ability to polymer nanocomposites provides new guidelines for strong, sustainable, and durable materials. Microcapsule-based self-healing materials work independently of an external stimulus such as pH, heat, light and solvent. In this paper, we developed autonomously self-healing UV-cured polyurethane graphene oxide nanocomposite coatings by means of efficient and useful copper-catalyzed azide-alkyne (CuAAC) click chemistry. Low molecular weight tetra-arm azide was successfully capsulated within poly(vinyl formal) capsules. Alkyne functional graphene-oxide reinforced nanocomposites containing azide microcapsules were prepared through photo-polymerization. The self-healing ability and anti-corrosion properties of the nanocomposites were studied after the damage occurred. The self-healing experiments show that the microcapsules provided a self-healing efficiency of around 70% after 24 h. Chemical, morphologic, mechanical, and thermal properties of the films were investigated. Furthermore, the electro-chemical analysis of films showed that the microcapsule containing films has a higher polarization resistance and a lower corrosion current.Publication Metadata only Structural and Dielectric Properties of Two Different BaTiO3/Polyaniline Nanocomposites(SPRINGER, 2013) ESMER, KADİR; Sipahioglu, S.; Madakbas, S.; Arda, L.; Esmer, K.Barium titanium oxide/polyaniline (BaTiO3/PANI) nano-composites were obtained in two different processes by the use of PANI and BaTiO3 nano-particles synthesized by the sol-gel technique. FT-IR, XRD, SEM and TGA measurements were taken for structural properties of all samples. The molecular interaction between BaTiO3 nanoparticles and PANI was between the H atoms in the N-H bond and the OH molecules in the solution environment. The said interaction was coordinated with BaTiO3 molecules over O atoms. XRD results confirmed that the synthesized BaTiO3 had a characteristic cubic perovskite structure and that its structure had not changed. TGA results revealed that the composites became more stable as the BaTiO3 amount increased. The dielectric measurement results are consistent with the structural results at higher frequencies. Dielectricity increased as BaTiO3 ratio increased in the environment. The change in the real part of the dielectric permittivity by frequency was stable at high frequencies. According to these results, it is concluded that the composite samples could have very high electromagnetic wave absorption values at higher frequencies (GHz).Publication Metadata only Thermal and Morphological Properties of Organo Modified Nanoclay/Polyethylene Terephthalate Composites(SPRINGER, 2017) KAHRAMAN, MEMET VEZİR; Madakbas, Seyfullah; Turk, Zeynep; Sen, Ferhat; Kahraman, Memet VezirThe purpose of this study is polyethylene terephthalate (PET) and modified organo-nanoclay with different masses and to contribute to the different areas of use and literature by examining these nanocomposites physical, chemical and thermal features. In this study, nanocomposite films, which work in PET that is a type of polymeric material, and work into modified organo-nanoclays with different percentages, obtained with the method called as in situ polymerization. The chemical structures of nanocomposites prepared were investigated by fourier transform infrared spectroscopy. The surface morphologies of this nanocomposites were examined by scanning electron microscope. Their thermal properties were analyzed by differential scanning calorimetry and thermogravimetric analysis. According to the results obtained, the thermal stabilities of modified nanoclay composites got better than PET. Besides, while the percent of clay in the doped PET was rising, its fragility increased. At the same time, high mass of clay formed when the percent of contribution developed. Thus, the surface interaction of polymer-clay decreased, because the composed aggregations prevented the polymer matrix from going into the layer of clay.Publication Metadata only Xylanase immobilization on functionalized polyaniline support by covalent attachment(WILEY-V C H VERLAG GMBH, 2013) KAHRAMAN, MEMET VEZİR; Madakbas, Seyfullah; Danis, Ozkan; Demir, Serap; Kahraman, Memet VezirChemically synthesized polyaniline (PANI) was used as polymeric support for xylanase immobilization. The polymer was first activated with glutaraldehyde and then xylanase was successfully immobilized. Xylanase bound polymer was characterized using FTIR. The optimum pH of the immobilized enzyme was at pH 5, which was shifted 1.0?pH unit to the acidic region when compared to the free enzyme. Thermal stability of the xylanase was improved with the immobilization. The characteristic properties of the immobilized and native enzyme, such as kinetic activity, reusability and storage stability were also studied at optimum pH and temperature. Immobilized enzyme exhibited better reusability and storage stability than the free one. Vmax values for the free and immobilized enzymes were calculated as 1.44 and 0.44?mg/mL/min, respectively. The Km values for the immobilized xylanase were found to be lower.Publication Metadata only İbuprofen ve parasetamolün çeşitli polimerik malzemelerden kontrollü salınımı(2019-12-20) MADAKBAŞ, SEYFULLAH; DEMİR, SERAP; Madakbaş S., Demir S., İmece B.
- «
- 1 (current)
- 2
- 3
- »