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 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.Publication Metadata only Sulfathiazole-based novel UV-cured hydrogel sorbents for mercury removal from aqueous solutions(PERGAMON-ELSEVIER SCIENCE LTD, 2009) KÖK YETİMOĞLU, ECE; Yetimoglu, Ece Koek; Kahraman, Memet Vezir; Bayramoglu, Guelay; Ercan, Oezgen; Apohan, Nilhan KayamanSulfathiazole-based novel hydrogel sorbents P(Sulti/hydroxyethyl methacrylate (HEMA)/acrylic acid (AAc)) were prepared by UV irradiation and used for the removal of mercury(II) ion from aqueous media. Hydrogels have been characterized by SEM and thermogravimetric analysis (TGA) techniques. The influence of the uptake conditions was investigated; maximum Hg(II) ion adsorption capacity obtained was 13.46 +/- 1.15mg g(-1) at pH 5.0. The hydrogels were tested several times without loss of adsorption capacity. The selectivity of the hydrogel towards to Hg(II), Cd(II) and Zn(II) ions tested was Hg>Cd>Zn. (C) 2008 Elsevier Ltd. All rights reserved.Publication Metadata only In vitro ortamda çimlendirilen pamuk (gossypium hirsutum l.) bitkisinde fenolik madde değişimlerinin incelenmesi(2003-09-08) KAHRAMAN, MEMET VEZİR; ÖZYİĞİT, İBRAHİM İLKER; Özyiğit İ. İ. , Ercan Ö., Kahraman M. V.Publication Metadata only Preparation and characterization of light curable hybrid coating: Its potential application for dental restorative material(SPRINGER, 2008) KAHRAMAN, MEMET VEZİR; Guengoer, Atilla; Kayaman-Apohan, Nilhan; Mert, Ayse; Kahraman, M. VezirThe objective of this study was to synthesize a dual-functional light curable resin by the reaction between acrylated cycloaliphatic epoxy resin and 3-isocyanatopropyltrimethoxysilane and investigate the performance of this oligomer in the preparation of resin-based composite restoratives. FT-IR and (29)Si-NMR were used to characterize the structure of the hybrids. The char yields of the hybrids increased with inorganic content comes from TEOS (tetraethylorthosilicate) and synthesized SiUA oligomers. Gel content of polymeric films was found to be between 95% and 98%. Swelling was found to be between 3.1% and 3.8%. Weight loss of coated human teeth in synthetic saliva solution was found to be among 1% and 2%. There was a systematic increase in the modulus and tensile strength with the increase of inorganic content. On the other hand, elongation at break did not changed. Prepared hybrid coating materials exhibited improvement in tensile properties and hardness, when photo chemically cured.Publication Metadata only Soybean oil based resin: A new tool for improved immobilization of alpha-amylase(WILEY, 2006) OGAN, AYŞE; Kahraman, MV; Kayaman-Apohan, N; Ogan, A; Gungor, AAcrylated epoxidized soybean resin has been utilized to immobilize the alpha-amylase via UV-curing technique. Among the numerous methods that exist for enzyme immobilization, entrapment and covalent binding are the focus of this study. The properties of immobilized enzyme were investigated and compared with those of the free enzyme. Upon immobilization by the two methods, the catalytic properties of the enzyme were not considerably changed as compared with that of nonimmobilized form; enzyme. The free enzyme lost its activity completely in 20 days, where as storage and repeated usage capability experiments demonstrated higher stability for the immobilized form. Immobilized enzyme prepared by attachment method possesses relatively higher activity compared with the activity of those obtained by entrapment method. (c) 2006 Wiley Periodicals, Inc.Publication Metadata only UV curable sulfonated hybrid materials and their performance as proton exchange membranes(ELSEVIER, 2009) KAHRAMAN, MEMET VEZİR; Gurtekin, M.; Kayaman-Apohan, N.; Kahraman, M. V.; Menceloglu, Y.; Gungor, A.In this study 2-acrylamido-2-methylpropanesulfonic acid (AMPS) containing UV curable nanocomposite membranes were prepared by using the sol-gel method. Tetraethylorthosilicate (TEOS), and 3-(methacryloyloxy)propyl trimethoxysilane (MAPTMS) were used, respectively as an inorganic precursor and coupling agent. Cross linking agents such as poly(ethylene glycol diacrylate) (PEGMA) and ethylene glycol dimethacrylate (EGDMA) were used to arrange the mechanical and physical properties of the resulting hybrid membrane. The hybrid formulation polymerized under UV irradiation and the gel percentage, water uptake of the membranes were calculated. The polymerization conversion of the organic part was investigated by using photo-differential scanning calorimetry (photo-DSC). The thermal and mechanical properties of the membranes indicated good stability. The morphological structure of membranes was investigated by scanning electron microscopy (SEM). In addition proton conductivity and methanol selectivity measurements were performed. The proton conductivity of the AMPS20-SOLGEL30 nanocomposite membrane is about 0.138 S cm(-1) at 50 degrees C. Selectivity toward methanol for the same membrane is very low with a selectivity factor of alpha = 0.032, which satisfies the requirements for DMFC applications. (C) 2009 Elsevier Ltd. All rights reserved.Publication Metadata only Synthesis of a novel bifunctional photoinitiator: Hybrid coatings on polycarbonate(WILEY-V C H VERLAG GMBH, 2007) KAHRAMAN, MEMET VEZİR; Kahraman, Memet Vezir; Kayaman-Apohan, Nilhan; Akdemir, Zumrut Seden; Boztoprak, Yalcin; Guengoer, AtillaThe objective of this study was to synthesize a new bifunctional photoinitiator by the reaction between 1-hydroxy-cyclohexyl-phenyl-ketone and 3-isocyanato propyl trimethoxysilane (ICPTMS) and examine its capability in the photoinitiation process comparing it with the unmodified photoinitiator. This new photoinitiator also acts as a coupling agent for inorganic and organic phases. Therefore, its effect on the physical and mechanical properties of UV-curable transparent organic-inorganic hybrid coatings was investigated. The presence of the new bifunctional photoinitiator and TEOS, increased the abrasion resistance and also improved the hardness of the polymeric films.Publication Metadata only Nonisocyanate based polyurethane/silica nanocomposites and their coating performance(SPRINGER, 2008) KAHRAMAN, MEMET VEZİR; Tueruenc, Oguz; Kayaman-Apohan, Nilhan; Kahraman, M. Vezir; Menceloglu, Yusuf; Guengoer, AtillaA series of silica nano-particles with different size were prepared by sol-gel technique, then surface modification by using cyclic carbonate functional organoalkoxysilane (CPS) was performed. Various amounts of carbonated silica particles directly added into carbonated soybean oil (CSBO) and carbonated polypropylene glycol (CPPG) resin mixture to prepare polyurethane-silica nanocomposite coating compositions by nonisocyanate route using an aliphatic diamine as a curing agent. Cupping, gloss, impact, and taber abrasion tests were performed on aluminum panels coated with those nano-composite formulations and tensile tests, thermogravimetric and SEM analyses were conducted on the free films prepared from the same coating formulations. An increase in abrasion resistance of CSBO-CPPG resin combination with the addition of silica was observed. In addition, the maximum weight loss of CSBO-CPPG resin combination was shifted to higher temperatures with incorporation of silica nano-particles The positive effect of modified silica particles on thermal stability of CSBO-CPPG system could be explained in such a way that PPG chains are able to disperse particles in the medium throughout the interactions between ether linkages and silanol groups.Publication Metadata only Covalent Immobilization of alpha-Amylase onto UV-Curable Coating(WILEY, 2009) KAHRAMAN, MEMET VEZİR; Yarar, Uemran; Kahraman, Memet VezirA UV-curable N-(4-sodiumsulfophenyl)maleimide monomer was synthesized, and its potential for enzyme binding was investigated. The bromine, which is used to activate the synthesized monomer for covalent attachments, has the advantage of giving reaction with the surface groups of enzyme under very mild conditions (0 degrees C, 30 min). In this procedure, sulfonyl bromide pendant monomer reacted with amino groups of the protein to form sulfonamide bonds. Polymeric support was prepaped by UV-curing technique. The water adsorption value was found to be less than 1%. The enzyme-bounding yield was found to be 68.18 +/- 4.20 mg/g monomer. The maximum activity was observed at pH 6.5. Immobilization did not change the pH-dependency of the enzyme activity. It was found that the optimum temperature for the free enzyme was similar to 30 degrees C, whereas it shifted to nearly 50 degrees C for the immobilized enzyme. Free enzyme lost its activity completely within 15 days. Immobilized enzyme lost only 30% of its activity in 30 days. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 3716-3722, 2009Publication Metadata only The novel use of organo alkoxy silane for the synthesis of organic-inorganic hybrid coatings(ELSEVIER, 2006) KAHRAMAN, MEMET VEZİR; Kahraman, M. Vezir; Kugu, Murat; Menceloglu, Yusuf; Kayaman-Apohan, Nilhan; Gungor, AtillaUV-curable, organic-morganic hybrid coatings based on a UV-curable epoxyacrylate resin (EA) and methacryloxypropyl trimethoxysilane were prepared by the sol-gel method. 2,2'-Bis(4-beta-hydroxy ethoxy) phenyl propane was modified by a coupling agent, 3-isocyanato propyl triethoxy silane, to improve the compatibility of the organic and inorganic phases. The formulations were applied onto Aluminum panels and cured by UV light to obtain a hard and clear coating with a good adhesion. The structural characterization of cured hybrid materials was performed using solid state Si-29 NMR spectroscopy. The real time infrared technique was used to follow the degree of double bond conversion and photopolymerization rate. The thermal properties of the coatings are improved depends on the 'component A' composition in hybrid mixture which was composed of methacryloxy propyl trimethoxysilane (MAPTMS) and trimethoxysilane terminated HEPA urethane (TMSHU). The char yield of pure epoxy acrylate resin was 0.7 wt% and that of 30 wt% of component A containing hybrid coating was 4.6 wt% at 900 degrees C in air atmosphere. The morphology of the hybrid materials was examined by scanning electron microscopy. The hybrids were nanocomposites. (c) 2006 Elsevier B.V. All rights reserved.