Person: KAHRAMAN, MEMET VEZİR
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KAHRAMAN
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MEMET VEZİR
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Publication Metadata only Synthesis and characterization of polyimide/hexagonal boron nitride composite(WILEY-BLACKWELL, 2012) KAHRAMAN, MEMET VEZİR; Kizilkaya, Canan; Mulazim, Yusuf; Kahraman, Memet Vezir; Apohan, Nilhan Kayaman; Gungor, AtillaPolyimide (PI)/hexagonal boron nitride (h-BN) composites were produced via the thermal imidization procedure from solution mixtures of a polyamicacid, which is prepared from 3,3',4,4'-benzophenonetetracarboxylic dianhydride and 3,3'-diaminodiphenyl sulfone (DADPS) in N-methyl-2-pyrrolidone (NMP), and alkoxysilane functionalized h-BN. The structure, thermostability, thermal behavior, and surface properties of the resulting materials were characterized by means of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM). The thermal characteristics of PI/h-BN films were better than the pure PIs. The physical and mechanical properties of the films were evaluated by various techniques such as contact angle, chemical resistance, and tensile tests. The flame retardancy of the composite materials was also examined by the limiting oxygen index (LOI). The experiments showed that the LOI values of PIs increased from 32 to 43 for the materials containing hexagonal boron nitride. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012Publication Metadata only Properties of Thiol-ene Photocurable Highly Hydrophobic and Oleophobic Nanocomposite Coatings on ABS and HIPS Substrates(WILEY-HINDAWI, 2013) ÇAKMAKÇI, EMRAH; Mulazim, Yusuf; Cakmakci, Emrah; Kahraman, Memet V.In this study, thiolene photocurable highly hydrophobic and oleophobic coatings were prepared and characterized. Trimethylolpropane tris(3-mercaptopropionate) and triallyl 1,3,5-triazine-2,4,6(1H,3H,5H)-trione were used for the preparation of the base formulation. Highly hydrophobic and oleophobic coatings were prepared with the aid of a fluorinated acrylate (Fluowet AC 812) and hydrophobic-fumed nanosilica particles. Nanoparticles were added for increasing the surface roughness and also to increase thermal and mechanical properties of the coatings. Coatings were applied on ABS (acrylonitrilebutadienestyrene) and HIPS (high impact polystyrene) substrates. As the fluorine and nanosilica contents were increased in the formulations, flame retardancy, hydrophobicity, and the oleophobicity of the coatings increased. Coatings were found to be highly thermally stable, highly solvent, and chemically resistant. The surface roughness of the coatings increased with the addition of hydrophobic-fumed nanosilica particles. In addition, the relation between the surface energy and the contact angle of the coatings was investigated. (c) 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E416E426, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21289Publication 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 Hybrid dual-curable cyanate ester/boron phosphate composites via sequential thiol-ene photopolymerization and thermal polymerization(ELSEVIER SCIENCE SA, 2014) KAHRAMAN, MEMET VEZİR; Sen, Ferhat; Kahraman, Memet VezirThe aim of this study was to improve hybrid dual-curable cyanate ester/boron phosphate composites via sequential thiol-ene photopolymerization and thermal polymerization for high performance applications such as aerospace and electronic devices. A novel 2,2'-diallylbisphenol A dicyanate ester (DA-BADCy) which is the allyl group containing cyanate ester was synthesized and characterized. DA-BADCy, silicon containing monofunctional thiol compound, trifunctional thiol compound and boron phosphate were cured using both ultraviolet (UV) and thermal methods. Using thiol-ene system, cyanate ester formulations, which are normally prepared at high temperatures, were prepared at room temperature. This study maintains ease of application for cyanate esters. Thermal stability, flammability and thermal conductivity of the samples were evaluated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), limiting oxygen index (LOI) and laser flash method, respectively. The samples were characterized with the following analysis; gel content, water absorption capacity and stress-strain test. Hydrophobicity of the samples was determined by the contact angle measurements. Moreover, the surface morphology of the samples was investigated by a scanning electron microscopy (SEM-EDS). The obtained results prove that the composites have good thermal and mechanical properties and with the help of easier preparation techniques, they can be used in many applications such as aerospace, electronic devices, materials engineering. (C) 2014 Elsevier B.V. All rights reserved.Publication Metadata only Surface and proton conductivity properties of electrospun poly(vinyl butyral)/polyaniline nanofibers(WILEY, 2018) ÇAKMAKÇI, EMRAH; Basturk, Emre; Cakmakci, Emrah; Madakbas, Seyfullah; Kahraman, Memet VezirProton-conductive electrospun nanofibers are promising potential materials for several advanced technological applications such batteries, sensors, and fuel cells. In this work, we prepared poly(vinyl butyral)/polyaniline (PVB/PANI) nanofibers via electrospinning and determined their proton conductivities. Structural characterization of the nanofibers was performed by FTIR analysis. Surface morphology of the nanofibers was determined by SEM and AFM. The addition of PANI significantly affected the fiber morphology, and over 90% reduction (with respect to neat PVB nanofibers) in the average nanofiber diameters was observed. Nanofiber mats were doped with polyphosphoric acid. The proton conductivity of the 2 wt.% PANI containing blend nanofibers was found as 18 x 10(-6) S/cm at room temperature and at 100% humidity.Publication Metadata only Adsorption of Ag (I) Ions from Aqueous Solutions Using Photocured Thiol-Ene Hydrogel(TAYLOR & FRANCIS INC, 2013) KÖK YETİMOĞLU, ECE; Firlak, Melike; Kahraman, Memet Vezir; Yetimoglu, Ece Kok; Zeytuncu, BihterIn this present work, we reported the adsorption and recovery studies of a P(Penta3MP4/PEG-DA/HEMA) thiol-ene based hydrogel. Real-time infrared spectroscopy technique was used to identify the photopolymerization kinetics of thiol-ene based formulations. The chemical composition and surface morphology of hydrogels were also characterized. The influence of the adsorption conditions such as pH, hydrogel formulations, contact time, initial metal ion concentration, and foreign metal ions on the metal ion binding capacity of hydrogel, were tested. Both the Langmuir and Freundlich isotherm models were applied to the method. The reusability of the hydrogels and the usability of the hydrogels for preconcentration studies were also investigated. The analytical parameters of the method were calculated and the recovery of silver ions from waste radiographic films was also applied to the hydrogels.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 Isosorbide Diallyl Based Antibacterial Thiol-Ene Photocured Coatings Containing Polymerizable Fluorous Quaternary Phosphonium Salt(AMER CHEMICAL SOC, 2019) ÇAKMAKÇI, EMRAH; Cakmakci, Emrah; Sen, Ferhat; Kahraman, M. VezirThe preparation of multifunctional, smart, and environmentally friendly coating materials is an innovative way to answer the needs in both today's and future technologies of coatings. In this work, antibacterial and environmentally friendly photocured coatings were prepared via a thiol-ene photopolymerization technique. First, with the aim to reduce the carbon footprint of the petroleum-based monomers, a greener alternative, isosorbide diallyl ether (IDE), was synthesized. Then a polymerizable fluorinated quaternary phosphonium salt (PFQPS) was synthesized to render the coatings antibacterial. PFQPS was added in different amounts (1%, 3%, 5%, and 10%) to the IDE-based thiol-ene-based formulations, and its effect on the thermal, mechanical, and optical properties were investigated. The prepared coatings exhibited exceptional antibacterial activity against E. coli and S. aureus. When the concentration of the PFQPS was 10%, the zone inhibition diameters were found as 82 +/- 5 and 18 +/- 1.9 for E. coli and S. aureus, respectively.Publication Metadata only Preparation of photocurable silica-titania hybrid coatings by an anhydrous sol-gel process(SPRINGER, 2011) KAHRAMAN, MEMET VEZİR; Altintas, Z.; Cakmakci, E.; Kahraman, M. V.; Apohan, N. K.; Gungor, A.Photocurable silica-titania hybrid coatings were prepared through an anhydrous sol-gel process. Moreover, test samples were prepared by the addition of definite ratios of fluoro acrylate oligomers into the formulations to manage the optical properties of transmitted light. Formulations were applied to corona-treated polycarbonate substrates. Upon adding the inorganic component to the coating material, thermal, mechanical, and other properties, such as hardness, gloss, contact angle, and flame resistance were improved. The photocured hybrid films showed an increase in the refractive index with increasing the titanium tetraisopropoxide content. As expected, a decrease was observed in the refractive index of the coatings with the incorporation of fluoro acrylate resin. The surface morphology of the hybrid films was characterized by ESEM analysis. In addition the chemical composition of the surface of the coatings was identified by ESEM-EDS technique. ESEM studies indicated that inorganic particles were dispersed homogenously throughout the organic matrix.