Person: ÇAKMAKÇI, EMRAH
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ÇAKMAKÇI
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EMRAH
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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 DOPO tethered Diels Alder clickable reactive silica nanoparticles for bismaleimide containing flame retardant thiol-ene nanocomposite coatings(ELSEVIER SCI LTD, 2017) OKTAY, BURCU; Oktay, Burcu; Cakmakci, EmrahThe modification of nanoparticles (NPs) with functional groups that render them much more compatible with the polymeric matrices to prepare organic-inorganic hybrid materials is an active area of research. In this work, flame retardant and reactive nanosilica particles were prepared. First, nanosilica particles were coated with aminosilane and then reacted with furfural to introduce Diels Alder clickable sites. Finally, these reactive NPs were phosphorylated by reacting them with 9,10-dihydro-9-oxy-10-phosphaphenanthrene-10-oxide (DOPO). Different amounts of DOPO tethered Diels Alder clickable nanosilica particles (DDAS) were added to a bismaleimide resin containing thiol-ene based liquid pho-tocurable mixture. Bismaleimide acted as a crosslinker between the organic matrix and DDAS NPs. The effects of DDAS on the thermal and mechanical properties and the curing kinetics of the photocured coatings were investigated. The addition of BMI increased the Tg of the coatings from 40 to 78 degrees C with respect to the base formulation. The presence of BMI improved the distribution of DDAS NPs in the organic matrix. Moreover, the thermal and the flame retardancy of the hybrid coatings were improved. While the LOI of the base formulation was found as 21.6%, with the introduction of DDAS NPs the LOI of the hybrid coatings was increased up to 24.1%. (C) 2017 Elsevier Ltd. All rights reserved.Publication Metadata only Preparation and characterization of flame retardant and proton conducting boron phosphate/polyimide composites(ELSEVIER SCI LTD, 2013) ÇAKMAKÇI, EMRAH; Cakmakci, Emrah; Gungor, AtillaIn this study novel flame retardant boron phosphate (BPO4)/polyimide composites were prepared. 4,4'-Oxydianiline (ODA) was reacted with 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) in dimethyl formamide (DMF) and mixed with BPO4 particles to obtain a series of polyamic acids, mean-while, corresponding polyimides were synthesized via the thermal imidization technique. The amount of BPO4 in the composite films was varied from 0 wt% to 10 wt%. The structure, thermal and surface properties of the polyimide films were characterized by means of ATR-FTIR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The flame retardancy of the composite materials was examined by limiting oxygen index (LOI) measurements and UL-94 VTM tests. Result showed that the LOI values of composites increased from 28 to 39. Furthermore, proton conductivity of polyimide films was measured by the four probe technique. The composite membrane containing 3 wt% of BPO4 showed a conductivity of 0.4 mS/cm at room temperature. (C) 2013 Elsevier Ltd. All rights reserved.Publication Metadata only Preparation of photo curable highly hydrophobic coatings using a modified castor oil derivative as a sol-gel component(ELSEVIER SCIENCE SA, 2011) ÇAKMAKÇI, EMRAH; Mulazim, Yusuf; Cakmakci, Emrah; Kahraman, Memet VezirModification and use of natural products have gained a lot of interest in recent years due to their environmental friendliness and their availability from different sources. In this study castor oil based photo curable highly hydrophobic coatings were prepared and characterized. Castor oil (CO) was first modified with 3-isocyanato propyl triethoxy silane and then it was hydrolyzed prior to the coating preparation. The resulting precursor was mixed with norbornyl acrylate, hexane diol diacrylate and hydrophobic coatings were prepared with the aid of fluorinated and nonfluorinated alkoxy silane coupling agents. The addition of fluorine showed a significant impact on the properties of the coatings. As the fluorine content was increased in the formulations, flame retardancy and the contact angle values of the coatings increased. The highest amount of fluorine containing coating showed a contact angle of 119 degrees. Then with the addition of nonfluorinatecl alkoxysilane compounds, a contact angle of 130 degrees was reached. Also the effect of post-cure temperature on contact angle values was investigated. (C) 2011 Elsevier B.V. All rights reserved.Publication 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 UV-Cured polypropylene mesh-reinforced composite polymer electrolyte membranes(WALTER DE GRUYTER GMBH, 2015) ÇAKMAKÇI, EMRAH; Cakmakci, Emrah; Ugur, Mustafa Hulusi; Gungor, AtillaIn this study, a polypropylene (PP) mesh was used to prepare proton- and Li+ conducting composite membranes for fuel cells and lithium rechargeable batteries, respectively. For the preparation of Li+ conducting membrane, polypropylene mesh was first immersed in an electrolyte solution, which was composed of LiBF4 and ethylene carbonate. Then the swollen membrane was immersed in an acetone solution of polyethylene glycol diacrylate (PEGDA), polyvinylidenefluoride-co-hexafluoro-propylene and photoinitiator. Finally, PP fabric was taken out from the solution and exposed to UV irradiation. Furthermore, proton conducting membranes were prepared by immersing the PP mesh into a mixture of vinyl phosphonic acid, PEGDA and photoinitiator. Afterwards, samples were cured under UV light. PP-reinforced membranes designed for fuel cell applications exhibited a room temperature conductivity of 3.3x10(-3) mS/cm, while UV-cured electrolyte for Li batteries showed ionic conductivities in the range of 1.61x10(-3)-5.4x10(-3) S/cm with respect to temperature. In addition, for lithium-doped composite polymer electrolyte (CPE), the electrochemical stability window was negligible below 4.75 V vs. Li/Li+. It is concluded that lithium-doped CPE has suitable electrochemical stability to allow the use of high-voltage electrode couples.Publication Metadata only Thermal Properties of Phosphorylated Nanodiamond Reinforced Polyimides(WILEY, 2016) ÇAKMAKÇI, EMRAH; Beyler-Cigil, Asli; Cakmakci, Emrah; Kahraman, Memet VezirRecently, the preparation of nanodiamond-polymer composites has attracted the attention of materials scientists due to the unique properties of nanodiamonds. In this study, novel polyimide (PI)/phosphorylated nanodiamonds (PNDs) composites were prepared. PNDs were achieved from the reaction of methylphosphonic dichloride with nanodiamonds in dichloromethane. Precursor of polyimide, which is the poly(amic acid) (PAA), was successfully synthesized with 3,30, 4,4'-benzophenonetetracarboxylic dianhydride and 4,4'-oxydianiline in the solution of N,N-dimethylformamide. Different ratios of phosphorylated nanodiamond particles were added into PAA solution and four different nanocomposite films were prepared. The amount of PNDs in the composite films was varied from 0 wt% to 3 wt%. The structure, thermal and surface properties of polyimide films were characterized by scanning electron microscopy (SEM), ATR-FTIR, thermogravimetric analysis (TGA), ultraviolet visible spectroscopy, and contact angle. SEM and FTIR results showed that the phosphorylated nanodiamond and PI/PNDs films were successfully prepared. Phosphorylated nanodiamonds were homogeneously dispersed in the polymer matrix and they displayed good compatibility. TGA results showed that the thermo-oxidative stability of PI/PNDs films was increased with the increasing amount of phosphorylated nanodiamond. (C) 2015 Society of Plastics EngineersPublication Metadata only Nonhydrolytic sol-gel synthesized oligosiloxane resin reinforced thiol-ene photocured coatings for the immobilization of acetylcholinesterase(SPRINGER, 2019) ÇAKMAKÇI, EMRAH; Cakmakci, Emrah; Demir, SerapAcetylcholinesterase (AChE), which is responsible for the hydrolysis of neurotransmitter acetylcholine, is a critical enzyme for the nervous system and also a biomarker for organophosphorous pesticide detection. The immobilization of AChE is an active area of research and recently the use of sol-gel-derived materials for enzyme immobilization has gained a lot of attraction. In this work, AChE was covalently immobilized onto a photocured substrate which was reinforced with an oligosiloxane resin. The oligosiloxane resin was designed to have both vinyl and epoxide groups and prepared via nonhydrolytic sol-gel technique. The strategy employed in this study offered a platform that has good mechanical and thermal properties and also suitable for modification. Thus, AChE was also immobilized onto these substrates after amine modification of the epoxy groups and followed by glutaraldehyde activation. Over 80% enzyme immobilization yield was achieved. At certain pH values (5.5 and 8.5) and under relatively higher temperatures (above 40 degrees C) the immobilized enzymes were found to have higher catalytic activity than the free enzyme. Furthermore, by immobilization the reuse and the storage stability of the enzyme was improved and the stability of the immobilized enzyme against the inhibitory effects of certain metal cations was enhanced [GRAPHICS] . Nonhydrolytic sol-gel synthesized oligosiloxane resin reinforced thiol-ene photocured coatings for the immobilization of acetylcholinesterase. Emrah CAKMAKCI, Serap DEMIR. HighlightsAn oligosiloxane resin was prepared via nonhydrolytic sol-gel technique.The oligosiloxane resin was used to reinforce thiol-ene photocured coatings.Acetylcholinesterase was immobilized onto the photocured coatings.By immobilization, storage stability, reuse and metal ion resistance were improved.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. Vezir