Person: KAHRAMAN, MEMET VEZİR
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KAHRAMAN
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MEMET VEZİR
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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 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 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 Designing Coconut Oil Encapsulated Poly(stearyl methacrylate-co-hydroxylethyl metacrylate) Based Microcapsule for Phase Change Materials(WILEY-V C H VERLAG GMBH, 2019) OKTAY, BURCU; Oktay, Burcu; Basturk, Emre; Kahraman, Memet Vezir; Apohan, Nilhan KayamanPhase change material (PCM) is an effective energy storage application, which has a relatively low cost. In this study, bio-based PCMs were prepared by using two techniques: encapsulation and UV-curing. Encapsulated-PCM was synthesized by suspension polymerization with stearyl methacrylate (SMA) and hydroxyethyl methacrylate (HEMA). In encapsulation process, the microcapsules were prepared from poly(stearyl methacrylate-co-hydroxyethyl methacrylate) shell and coconut oil (CO) core. UV-cured form stable PCM was also prepared by radical addition polymerization of stearyl methacrylate, hydroxyethyl methacrylate and coconut oil. In UV-curing process as in the second process, coconut oil was trapped within the polymeric network without covalent bonding. Thermal storage feature of encapsulated-PCM and UV-cured form stable PCM was investigated. The melting enthalpy of encapsulated-PCM is 119J/g, which is higher than both the melting enthalpy of pure coconut oil (106J/g) and UV-cured form stable PCM (47J/g). Moreover, thermal degradation results of PCMs show that the maximum thermal decomposition temperature of encapsulated-PCM increased compared with UV-cured from stable PCM.Publication Metadata only Preparation and Characterization of Thermally Conductive Thermoplastic Polyurethane/h-BN Nanocomposites(WILEY, 2014) ÇAKMAKÇI, EMRAH; Cakmakci, Emrah; Kocyigit, Ciler; Cakir, Selma; Durmus, Ali; Kahraman, M. VezirPublication Metadata only Preparation of thiol-ene based photo-crosslinked polymer as a potential phase change material(ELSEVIER SCIENCE SA, 2016) KAHRAMAN, MEMET VEZİR; Basturk, Emre; Deniz, Duygu Yuksel; Kahraman, Memet VezirA series of novel photo-crosslinked thiol-ene based shape-stabilized phase change materials (PCMs) have been prepared for the use of thermal energy storage applications. Four types of formulations were prepared with different fatty alcohols by adding di(trimethylolpropane) tetraacrylate (TMPTA), polyethylene (glycol) diacrylate (PEGDA) and pentaerythritoltetrakis(3-mercaptopropionate) (4-SH) in which we investigated their properties as shape-stabilized PCMs. Fatty alcohols, 1-Octadecanol, 1-Eicosanol and 1-Docosanol, were added to the formulations, respectively. The characterization tests were performed by ATR-FTIR spectroscopy. Phase change behaviors and thermal performances were investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis system (TGA).The heating cycle phase change enthalpy is measured between 27 and 43 J/g, and the freezing cycle phase change enthalpy is found between 20 and 39 J/g. The decomposition of UV-cured PCMs started at 413 degrees C.The results indicate that the photo-crosslinked thiol-ene based PCMs possess good phase change properties and have an applicable temperature range. With the obtained results these materials promise a great potential in thermal energy storage applications. (C) 2016 Elsevier B.V. All rights reserved.Publication Metadata only Synthesis of B/P/N Containing Flame-Retardant Additives and UV Curable Hybrid Coating Applications(WILEY, 2017) KAHRAMAN, MEMET VEZİR; Ocakoglu, Melike; Sen, Ferhat; Kahraman, Memet VezirThe aim of this study is to synthesize flame-retardant additive by using B/P/N and to investigate this additive's performance in the ultraviolet (UV) curable system. Therefore, in the first stage, borate ester (triethanolamine borate, TEAB) was synthesized by the reaction of boric acid and triethanolamine. In the second stage, phosphate salt of borate ester (triethanolamine borate polyphosphoric acid, TEAB-PPA) was synthesized by the reaction of borate ester (TEAB), which synthesized in the first stage and PPA. Thermal stability and flammability of the samples were evaluated by thermal gravimetric analysis, differential scanning calorimetry, and limiting oxygen index. The samples were characterized with the following analyses: Fourier transform infrared, nuclear magnetic resonance, UV transmittance, gel content, water absorption capacity, and stress-strain test. Hydrophilicity of the samples was determined by the contact angle measurements. Moreover, the surface morphology of the samples was investigated by a scanning electron microscopy-energy dispersive spectrometer mapping. The obtained results prove that boron, nitrogen, and phosphorus increased the flame retardancy property of the synthesized additive and suggest desired flame retardancy using various resins and different ratio of additives.Publication Metadata only Thermally Stable Phosphonium Organoclay-Reinforced Polyimide Nanocomposites(TAYLOR & FRANCIS INC, 2017) ÇAKMAKÇI, EMRAH; Birtane, Hatice; Beyler-Cigil, Asli; Cakmakci, Emrah; Kahraman, Memet VezirTo prepare clay containing high-temperature processable polymer nanocomposites, new cation exchangeable agents with high thermal stability are required. In this work, we investigated the effect of a thermally stable phosphonium-modified organoclay on the properties of polyimides prepared from the reaction of 4,4-oxydianiline with 3,3,4,4-benzophenonetetracarboxylic dianhydride. The organoclay was prepared from the reaction of pristine clay with octyltriphenylphosphonium bromide. Phosphonium-modified clay displayed a negligible weight loss (<5%) below 300 degrees C. The thermal stability of the composites enhanced with the increasing amount of phosphonium-modified clay.