Person: KAHRAMAN, MEMET VEZİR
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KAHRAMAN
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MEMET VEZİR
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Publication Metadata only Encapsulation of trichloroacetic acid and trifluoroacetic acid for autonomous self healing coatings(TAYLOR & FRANCIS INC, 2020) KAHRAMAN, MEMET VEZİR; Tezel, Ozge; Beyler Cigil, Asli; Kahraman, Memet VezirMicrocapsules with TFA or TCA healing agents with an outer poly(melamine-urea-formaldehyde) (PMUF) were successfully synthesized for the first time, according to a review of published literature. The average sizes of the microcapsules obtained were measured to be 1.7 and 2 mu m for TFA/PMUF and TCA/PMUF, respectively. Both microcapsules were separately added to an epoxy-based coating formulation. To examine the self-healing properties, scanning electron microscopy images were examined at the moment that damage occurred and seven days later. A self-healing experiment showed that the more reactive PMUF/TFA microcapsules were more efficient than the PMUF/TCA microcapsules in repairing scratch damage in the coatings.Publication Metadata only Allyl Phosphonium Salt-Modified Clay for Photocured Coatings: Influence on the Properties of Polyester Acrylate-Based Coatings(WILEY, 2015) ÇAKMAKÇI, EMRAH; Zeytuncu, Bihter; Cakmakci, Emrah; Kahraman, Memet VezirIn this study, bentonite clay was modified with a phosphonium salt and this modified clay was used to prepare polyester acrylate based coatings to improve their flame retardancy and mechanical properties. Photocured composites were prepared with 1, 2, and 3 wt% phosphonium salt modified clay and for comparison 1 wt% nonmodified clay containing composites were also prepared. Modified clay displayed good dispersion properties due to its increased basal spacing. Composites were characterized by FT-IR and XRD measurements. According to XRD results, it was found that the modified clay was exfoliated in the composites. Furthermore, we investigated the effect of allyl phosphonium salt modified clay on the thermal, mechanical, and flame retardant properties of polyester acrylate based composites coatings. When compared with neat clay containing coatings, modified clay containing photocured coatings exhibited increased modulus and enhanced thermal properties due to increased crosslinking density. Moreover, the presence of the phosphonium salt enhanced the flame retardancy of the polyester based coatings. POLYM. COMPOS., 36:946-954, 2015. (c) 2014 Society of Plastics EngineersPublication Metadata only Quaternary imidazolium-functionalized reactive silica nanoparticles-containing thiol-ene photocured antibacterial hybrid coatings(Elsevier B.V., 2022) ÇAKMAKÇI, EMRAH; Şen F., Kocatürk E., Çakmakçı E., Kahraman M.V.The need for antibacterial coatings is increasing day by day. In this study, coating materials that do not contain antibacterial agents but have antibacterial properties have been developed. First, two different quaternary imidazole compounds were synthesized. Then, silica nanoparticles were modified with these quaternary agents. By using 1%, 3% and 5% modified silica nanoparticles, UV cured coating materials were obtained according to the thiol-ene reaction mechanism. Mechanical, thermal, surface, structural, optical and antibacterial analyzes of the obtained coatings were performed. The analyzes revealed that UV cured antibacterial coating materials have been successfully synthesized and can be used as a new and unique coating material for the coating industry. © 2021 Elsevier B.V.Publication Metadata only Phosphorus Ester Containing Mesoporous Silica as Novel High-Effective Flame Retardant in Polyurethane and Polyester Coatings(WILEY-V C H VERLAG GMBH, 2021) KAHRAMAN, MEMET VEZİR; Aytan, Emre; Aytan, Tugce Akbal; Kahraman, Memet VezirIn this study mesoporous silica spheres (MPSs) and polyphosphoric acid based organophosphate ester flame retardant (FR material) material were synthesized and flame retardancy performance in acrylate-based polyurethanes (PUR) and polyester (PET) resins investigated. For this, both MPSs and FR material were synthesized according to literature and FR material was loaded into MPSs which takes the role of carrier. Loaded MPSs were put into UV curable PUR and PET resins and polymerized under UV radiation. Their characteristics were investigated by FT-IR, TGA, LOI, SEM and TEM. The results showed that FR material had excellent flame-retardant abilities for both PUR and PET series. The TGA curves suggested that synthesized FR material shows lower thermal stability at low temperatures than original materials however it showed good ability of char formation at higher temperatures, therefore improving the flame retardant property of samples. Moreover the LOI analysis showed that flame retardancy properties were improved significantly. The additive increased the LOI value from 20,5 and 21 to 26,5 and 27.Publication Metadata only Preparation and drug release properties of lignin-starch biodegradable films(WILEY-V C H VERLAG GMBH, 2012) OGAN, AYŞE; Calgeris, Ilker; Cakmakci, Emrah; Ogan, Ayse; Kahraman, M. Vezir; Kayaman-Apohan, NilhanStarch is one of the most commonly available natural polymers which are obtained from agro-sources. It is renewable and abundant in nature. Unfortunately due to its poor mechanical properties and hygroscopic nature, there are some strong limitations to the development of starch-based products. Usually blends of starch are prepared and plasticized with glycerol to improve some of its properties. In this study, lignin was extracted from hazelnut shells and investigated as a potential additive for starch biofilms. The structural characterization of hazelnut lignin was performed by employing UV spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Lignin was blended with corn starch in different ratios to obtain biofilms. Mechanical and thermal properties of the biofilms were enhanced as the lignin amount was increased in the formulations. Water absorption tests were performed at pH 2.0, 4.0, and 6.0. The percent swelling values of the starch/lignin films increased as pH increased. Also, the biofilm exhibiting the best properties was chosen for the drug release studies. Biofilms showed a fast ciprofloxacin (CPF) release within an hour and then the drug release rate decreased. A pH dependent drug release mechanism was also observed according to KoshnerPeppas model. The drug release increased with a decrease in pH.Publication Metadata only Photocurable cyanate ester containing hybrid coatings by an anhydrous sol-gel technique(ELSEVIER SCIENCE SA, 2012) KAHRAMAN, MEMET VEZİR; Bayramoglu, Gulay; Ahbab, Ibrahim; Kahraman, M. Vezir; Gungor, AtillaThis work reports the synthesis and characterization of hybrid coatings obtained by UV curable anhydrous sol-gel process. Chemical structure of the products was confirmed using spectroscopic methods such as infrared and nuclear magnetic resonance spectroscopy. The properties of the hybrid coatings such as thermal and mechanical properties were investigated in detail by scanning electron microscope, thermogravimetric analysis, and mechanical measurement. Cure kinetics of the coating formulations was investigated by differential scanning photo-calorimetry (Photo-DSC). Cross cut adhesion, pendulum hardness, gloss, pencil hardness. MEK rub test were also performed to measure the coating performance of the hybrid coatings. The results indicate that the addition of the appropriate amount of CPM and sol-gel can effectively improve the thermal and mechanical properties. (C) 2012 Elsevier B.V. All rights reserved.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 Covalently bonded nanosilver-hydroxyethyl cellulose/polyacrylic acid/sorbitol hybrid matrix: thermal, morphological and antibacterial properties(SPRINGER, 2022) BİRTANE, HATİCE; Cigil, Asli Beyler; Sen, Ferhat; Birtane, Hatice; Kahraman, Memet VezirIn this study, an antibacterial, biodegradable, biocompatible, and environmentally friendly coating was prepared with an easy technique. Accordingly, Ag nanoparticles were synthesized to provide antibacterial properties to the coating, and its surface was modified with (3-Glycidyloxypropyl)trimethoxysilane (GPTMS) in order not to clump in the coating, to ensure homogeneous distribution on the surface, and to covalently bond to the coating. While preparing the coating formulation, polyacrylic acid (PAA), which are natural polymers, and hydroxyethyl cellulose (HEC), a derivative of cellulose, were preferred to reduce the consumption of petroleum derivatives. Then, sorbitol was used as a plasticizer. Synthesized Ag nanoparticles were included in the coating formulation containing PAA/HEC and sorbitol and thermally crosslinked at a high temperature. The size of Ag nanoparticles was analyzed by DLS while chemical composition after modification was analyzed by FTIR. Then, the chemical structure, thermal properties, surface properties, and antibacterial properties of the environmentally-friendly film were examined. It was observed that Ag nanoparticles, the surface of which were modified with GPTMS containing silicon groups, increased the thermal stability of the film, and the presence of Si and Ag on the surface was detected in SEM-EDAX measurements, and this showed that the aimed coating was obtained. It was observed that silver nanoparticles, of which their surface was modified, incorporated into the coating obtained from PAA and HEC, which are known to have no antibacterial properties, showed antibacterial activity against E. coli and S. aureus. The zone of inhibition was measured as 11 mm for both E. coli and S. aureus.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 Synthesis and characterization of UV-curable dual hybrid oligomers based on epoxy acrylate containing pendant alkoxysilane groups(ELSEVIER SCIENCE SA, 2006) KAHRAMAN, MEMET VEZİR; Bayramoglu, Gulay; Kahraman, M. Vezir; Kayaman-Apohan, Nilhan; Gungor, AtillaThis work involves the synthesis of novel hybrid oligomers based on a UV-curable epoxy acrylate resin (EA). The EA resin was modified with various amount of 3-isocyanatopropyl trimethoxysilane (IPTMS) coupling agent. The modification percentage of the hybrid oligomer was varied from 0 to 50 wt.%. UV-curable, hard and transparent organic-inorganic hybrid coatings were prepared on Plexiglas substrates and their characterization was performed by the analyses of various properties such as hardness, gloss, tape adhesion test and stress-strain test. Results from the mechanical measurements show that the properties of hybrid coatings improve with the increase in modification ratio. The thermal behavior of coatings was also evaluated. It is observed that the thermal stability of epoxy acrylate coatings is enhanced with incorporation of siloxane. Gas chromatography/mass spectrometry analyses showed that the initial weight loss obtained in thermogravimetric analysis is due to the degradation products of the photoinitator and the acrylic acid moiety of acrylic monomers. (c) 2006 Elsevier B.V. All rights reserved.