Person: KAHRAMAN, MEMET VEZİR
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KAHRAMAN
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MEMET VEZİR
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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 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 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 Thermal and neutron shielding properties of (B2O3)-B-10/polyimide hybrid materials(SPRINGER, 2011) KAHRAMAN, MEMET VEZİR; Mulazim, Yusuf; Kizilkaya, Canan; Kahraman, Memet VezirIn this study, (B2O3)-B-10/polyimide (PI) hybrid materials were synthesized with the aim to improve their thermal stability and neutron shielding properties. 3,3'-Diaminodiphenyl sulfone (DADPS) reacted with 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) in N-methyl-2-pyrrolidone (NMP) and mixed with amine functionalized (B2O3)-B-10 to prepare a series of poly (amic acid), meanwhile, corresponding PIs were obtained via the thermal imidization procedures. The morphologies and structures of the prepared hybrid materials were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The thermooxidative and flame retardancy properties of the PI films were examined by thermogravimetric analysis (TGA) and limiting oxygen A +/- ndex (LOI). The experimental results showed that as the amount of functionalized (B2O3)-B-10 was increased, flame retardant properties of the hybrid films were increased. Hybrid materials were also irradiated with thermal neutrons. The neutron shielding properties increasing depends on the amount and the distribution of the B-10 isotope.Publication Metadata only Preparation and characterization of UV-curable polymeric support for covalent immobilization of xylanase enzyme(ELSEVIER, 2011) KAHRAMAN, MEMET VEZİR; Akdemir, Zumrut Seden; Demir, Serap; Kahraman, M. Vezir; Apohan, Nilhan KayamanThe hydroxyl group of poly(ethylene glycol) monoacrylate (PEGMA) was activated by 1 1'-carbonyldiimidazole (CDI) and then a xylanase enzyme was immobilized to amine active PEGMA UV-curable polymeric support formulation was prepared by mixing the xylanase bonded PEGMA aliphatic polyester 2-hydroxyethyl methacrylate (HEMA) poly(ethylene glycol) diacrylate (PEGDA) and photoinitiator After UV irradiation the enzymatic activity of the polymeric matrix was evaluated and compared with the corresponding free enzyme By immobilization the temperature resistance of the enzyme was improved and showed maximum activity at 60 C pH dependent activities of the free and immobilized enzymes were also investigated and it was found that the pH of maximum activity for the free enzyme was 60 while for the optimal pH of the immobilized enzyme was 65 The immobilized enzyme retained 75% of its activity after 33 runs The morphology of the polymeric support was characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) coupled with SEM was used to explore the chemical composition The results have confirmed the evidence of enzyme in the structure of the polymeric material (c) 2010 Elsevier B V All rights reservedPublication Metadata only Removal of Ag(I) from Aqueous Solutions by Thiol-ene-Based Hydrogel and Its Application to Radiographic Films(SPRINGER, 2014) KÖK YETİMOĞLU, ECE; Firlak, Melike; Kahraman, Memet Vezir; Yetimoglu, Ece KokThe thiol-ene-based P(Penta3MP4/PEGDA/AAc) hydrogels were prepared by UV curing technique, then characterized and used as adsorbents for the investigation of the effect of process parameters such as pH of solution, contact time, and initial concentration of solution, on the removal of Ag(I) from aqueous solution. The results indicate that the adsorption of Ag(I) ions from aqueous solutions is strongly dependent on pH under experimental conditions. Both Langmuir and Freundlich isotherm models were applied to experimental data, and the results show that the adsorption process is well fitted to the Langmuir isotherm model. Selectivity, reusability, and applicability of hydrogels to radiographic film waste were investigated.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 Fabrication of photo-cross-linked polyethyleneimine-based barriers for CO2 capture(WILEY-BLACKWELL, 2015) KAHRAMAN, MEMET VEZİR; Eminoglu, Elif Merve; Beypinar, Feriha; Kahraman, Memet Vezir; Durmus, AliIn this study, first, polyethyleneimine was acrylated and mixed with polyvinyl alcohol solution to prepare photo-crosslinked polyethyleneimine (PEI)-based nanofibers by utilizing ultraviolet and electrospinning technique at the same time. For CO2 permeability testing, same formulations were prepared by using solvent casting technique and exposed to ultraviolet light to have polyethyleneimine-based membrane films. The chemical structures of the nanofibers were characterized by Fourier transform infrared spectroscopy. The thermal properties of nanofibers were examined by thermal gravimetric analysis and differential scanning calorimeter. The morphology of nanofibers was investigated by scanning electron microscopy. CO2 permeabilities of samples were also measured. Copyright (C) 2015 John Wiley & Sons, Ltd.