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Öğe Adhesion and Corrosion Resistance Properties of Coatings Obtained From Modified Low-Molecular-Weight Polystyrenes(Taylor & Francis Ltd, 2006) Ahmetli, Gülnare; Kocak, A.; Sen, N.; Kurbanlı, R.In this study, as a continuation of our previous studies, chemical modification of low-molecular-weight polystyrenes (PSs) was carried out with various functional group modifiers: epichlorohydrin (ECH), maleic anhydride (MA) and acetic anhydride (AA), in a single stage using a cationic catalyst. It was determined that the amounts of the functional groups bound to the structure of the polymer depended on the molecular weight of the polymer used, and more functional groups were bound to the lower-molecular-weight PSs. It was found that the coating properties (adhesion properties and resistance to aggressive conditions) of the functional group containing PS to the metal surface depended on the structure and the amount of the functional groups bound to the aromatic ring of the polymer. In addition, it was observed that the PS modified with MA and ECH having carboxyl- and epoxy-groups in their aromatic rings had higher adhesion, as well as higher corrosion resistance properties. Various functional groups bound to the aromatic ring of the polystyrene and their amounts were determined by spectral and chemical analysis methods.Öğe Doğal atık malzemeler ve biyoçarları ile biyobozunur özellikte yeni epoksi-bazlı kompozitlerin hazırlanması ve karakterizasyonu(2018) Kocaman, Süheyla; Ahmetli, Gülnare; Soğancıoğlu, MerveBu çalışmada doğal atık malzemelerden ceviz kabuğu (CK) ve pirina bisfenol-A tipi epoksi reçine (ER) kompozitlerinin hazırlanması için dolgu maddesi olarak kullanılmıştır. Ayrıca, doğal takviye malzemeleri 700 ºC’da piroliz edilerek katı ürün atığı çarla da kompozitleri oluşturulmuştur. Epoksi reçinede dolgu oranı %10-50 aralığında değiştirilerek kompozitlerin mekanik, elektriksel, iletkenlik ve termal özelliklerine dolgu maddesi oranının etkisi araştırılmıştır. Çarların morfolojisi taramalı elektron mikroskobu (SEM) ile incelenmiştir. Ayrıca, elde edilen biyobazlı kompozit malzemeler özel olarak hazırladığımız toprağa gömülerek bozunma süreleri (biyobozunurluk testi) belirlenmiştir.Öğe Equilibrium isotherm studies for the uptake of cadmium and lead ions onto sugar beet pulp(ELSEVIER SCI LTD, 2008) Pehlivan, E.; Yanik, B. H.; Ahmetli, Gülnare; Pehlivan, M.The adsorption of Cd2+ and Pb2+ on sugar beet pulp (SBP), a low-cost material, has been studied. In the present work, the abilities of native (SBP) to remove cadmium (Cd2+) and lead (Pb2+) ions from aqueous solutions were compared. The (SBP) an industrial by product and solid waste of sugar industry were used for the removal of Cd2+ and Pb2+ ions from aqueous water. Batch adsorption studies were carried out to examine the influence of various parameters such as initial pH, adsorbent dose, initial metal ion concentration, and time on uptake. The sorption process was relatively fast and equilibrium was reached after about 70 min of contact. As much as 70-75% removal of Cd2+ and Pb2+ ions for (SBP) are possible in about 70 min, respectively, under the batch test conditions. Uptake of Cd2+ and Pb2+ ions on (SBP) showed a pH-dependent profile. The overall uptake for the (SBP) is at a maximum at pH 5.3 and gives up to 46.1 mg g(-1) for Cd2+ and at pH 5.0 and gives 43.5 mg g(-1) for Pb2+ for (SBP), which seems to be removed exclusively by ion exchange, physical sorption and chelation. A dose of 8 g L-1 was sufficient for the optimum removal of both the metal ions. The Freundlich represented the sorption data for (SBP). In the presence of 0.1 M NaNO3 the level of metal ion uptake was found to reach its maximum value very rapidly with the speed increasing both with the (SPB) concentration and with increasing initial pH of the suspension. The reversibility of the process was investigated. The desorption of Cd2+ and Pb2+ ions which were previously deposited on the (SBP) back into the deionised water was observed only in acidic pH values during one day study period and was generally rather low. The extent of adsorption for both metals increased along with an increase of the (SBP) dosage. (SBP), which is cheap and highly selective, therefore seems to be a promising substrate to entrap heavy metals in aqueous solutions. (C) 2007 Elsevier Ltd. All rights reserved.Öğe Evaluation of fatty acid waste in the synthesis of oligo(ether-ester)s(HINDAWI LTD, 2019) Kocaman, S.; Cerit, A.; Soydal, U.; Marti, M. E.; Ahmetli, GülnareIn this study, the waste of sunflower oil refinement was converted to a fatty acid glycidyl ester (FAGE). An unsaturated oligo(ether-ester) (OEE) was synthesized by ring-opening polymerization using propylene oxide (PO) and FAGE. Oligo(ether-ester) production was achieved with a high yield of 80% at 5 h and 0 degrees C when the mole ratio of PO : FAGE was 1 : 1. Synthesized OEE was characterized by FTIR and several chemical analysis methods. According to the TGA results, T-5, T-10, and T-50 values of OEE-styrene copolymers increased up to a 7 : 3 mole ratio then decreased. The weight losses of these copolymers changed in the range of 3-5%. The data of longitudinal and transversal wave velocities showed that copolymers with styrene had better elastic properties and impact resistances compared to those with pure polystyrene.Öğe Fe(II/III) adsorption onto styrene/divinyl benzene based polymers(JOHN WILEY & SONS INC, 2007) Ahmetli, Gülnare; Tarlan, E.The effectiveness of two styrene/divinyl benzene (SDB) compounds was studied for the removal of Fe(II) and Fe(III) from aqueous solutions. The first one was styrene/divinyl benzene sulfonate (SDB-S), which was commercially supplied and used as an ion-exchange resin. The second one was a terpolymer, styrene/divinyl benzene/allyl methacrylate (SDBAM), which was synthesized from the monomers and used as an adsorbent. Fe(II/III) removal experiments were conducted in columns and in batch reactors. The results indicated that both SDB compounds were effective for both Fe(II) and Fe(III) removal. The ion-exchange capacity of SDB-S was calculated to be 907 mequiv/100 g for Fe(II) and 1100 mequiv/100 g for Fe(III) (which are good quantities). The adsorptive capacity of SDBAM, determined from isotherm calculations, was 79 mequiv/100 g for Fe(II) and 70 mequiv/100 g for Fe(III). This was less than the adsorptive capacity of SDB-S but acceptable in comparison with common adsorbents. The SDB compounds were more selective for Fe(II). (c) 2007 Wiley Periodicals, Inc.Öğe Investigation of Pb(II) Adsorption Onto Natural and Synthetic Polymers(Wiley, 2012) Ahmetli, Gülnare; Yel, E.; Deveci, H.; Bravo, Z.; Bravo, Y.Adsorption of toxic metal ion Pb(II) onto two different insoluble humic acids (IHAs) obtained from Beysehir (BIHA) and Ermenek (EIHA) low grade lignites and two synthesized terpolymers: styrene-divinylbenzene-methacrylic acid (SDBM) and styrene-divinylbenzene allylmethacrylate (SDBAM) were investigated and compared with commercial activated carbon (AC). The synthesized polymers were characterized by FTIR. Effects of pH (in neutral and acidic range), time, and initial metal concentration on the effectiveness of IHAs and terpolymers were determined. All synthesized adsorbents could adsorb Pb(II) with much higher capacity at half of the retention of AC in acidic medium. The adsorption capacities varied in the range of 5176 mg g-1. The affinity order of polymers in acidic medium for Pb(II) ions was observed as: SDBAM>SDBM>BIHAEIHA>AC. IHAs fit Freundlich model while SDB polymers were fitting Langmuir isotherm. The maximum adsorption capacities in neutral medium were 48 mg g-1 for SDBM and 15 mg g-1 for BIHA. Desorption studies for the polymer of highest performance indicated that about 90% desorption was achieved at 5 h by using EDTA regenerant solution. The polymer can be used repeatedly in Pb(II) adsorption with close capacities to initial use. The higher selectivity of SDBAM to Pb(II) ions in multimetal solution was also indicated in the study.Öğe Mechanical And Thermal Studies On Epoxy Toluene Oligomer-Modified Epoxy Resin/Marble Waste Composites(WILEY, 2012) Ahmetli, Gülnare; Koçak, Nuriye; Dağ, Mustafa; Kurbanlı, RefikaIn this research, marble dust waste was recycled as raw material for the preparation of composite materials. Epoxy toluene oligomer (ETO) was synthesized from toluene and epichlorohydrin, which was used as a comatrix in 50 wt% with commercial epoxy resin (ER). Its chemical structure was characterized with Fourier transform infrared spectroscopy and chemical analyses. The rigid filler used in epoxy polymer matrix was the marble processing waste obtained from wastewater using different coagulants, such as sepiolite, zeolite, or pumice. The thermal and mechanical properties of the composites were evaluated with thermogravimetric and mechanical analyses. The results showed that the marble wastes with all coagulants can significantly improve the thermal stability of an ERETO matrix at temperatures above 350 degrees C. Composites exhibited a higher thermal degradation temperature with a much higher char yield. Surface hardness and tensile strength of the composites were higher than those of pure epoxy polymer matrix, as well. Scanning electron microscopy was used for the characterization of surface and cross-sections of the composites to verify the results. POLYM. COMPOS., 2012. (c) 2012 Society of Plastics EngineersÖğe Modified Polystyrenes: Corrosion, Physicomechanical and Thermal Properties Evaluation(Elsevier Science Sa, 2012) Deveci, Hüseyin; Ahmetli, Gülnare; Ersöz, Mustafa; Kurbanh, RefikaCoating metal surfaces with polymers is a protective method against corrosion. It is known that the introduction of anionic hydrophylic groups enhances the adhesive property and protective functionality of polymers. In the present work, polystyrene (PS) was chemically modified with siiccinic (SAH) and phthalic (PhAH) anhydrides in the presence of BF3 center dot O(C2H5)(2) cationic catalyst. The modified polystyrenes (MPSs) were characterized by FTIR and H-1 NMR spectroscopy. The effect of various carboxylic groups bound to the PS's aromatic ring on the adhesion, corrosion, elastic properties and thermal behavior was studied in comparison with pure PS. All MPSs syntesized in this work, show strong adhesion to the substrate. The modifications enhanced the adhesion on metal surface of PS from 2% to 97-98%. Moreover, chemical modifications also enhanced the physico-mechanical properties of PS like surface hardness. tensile strength, percentage elongation and stress at maximum load. The best results were obtained for MPS with PhAH. (C) 2011 Elsevier B.V. All rights reserved.Öğe Optical Properties of Modified Epoxy Resin with Various Oxime Derivatives in the UV-ViS Spectral Region(WILEY, 2011) Durmuş, Haziret; Şafak, Haluk; Akbaş, Hatice Zehra; Ahmetli, GülnareOptical absorbance measurements have been performed on the epoxy resin and the composites prepared by its modification with two different oxime derivatives (benzaldoxime and 2-furaldoxime) in the wavelength interval of 190-680 nm by unpolarized light. Using the experimental absorbance data, dielectric constant and refractive index dispersion have been determined by means of standard oscillator fit procedure. Moreover, based on the dispersion analysis, direct and indirect band gap energies of the samples have been calculated. It is found that direct band energy for epoxy is nearly 3.49 eV, while its value for the oxime derivatives has been increased up to the 4.15 eV. Another important result to be pointed out is that the absorbance for the 2-furaldoxime doped resin has been greatly increased in a respectively, narrow interval (similar to 30 nm wide) in the UV region, while in the case for the benzaldoxime doped sample, a decreasing has been observed in the absorbance at the same region. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 1490-1495, 2011Öğe Synthesis and Metal Ions Sorption Properties of Styrene-Based Polymers(WILEY, 2009) Deveci, Hüseyin; Ahmetli, Gülnare; Ersöz, Mustafa; Kurbanlı, RefikaAtactic polystyrene (PS) was chemically modified with maleic (MAH), succinic (SAH), and phtalic (PhAH) anhydrides. Styrene was copolymerized with acrylic (AA) and methacrylic acids (MA). Amount of carboxyl groups (%) bound to polymers was determined in the range of 6.9-25.9. Different modified polystyrenes (MPS) and styrene copolymers were used in the experiments to study Cu(II) and Zn(II) ions adsorption probability and their comparison. Sorption capacity of the polymers for the metal ions were investigated in aqueous media containing different amounts of these ions (540 mg/L) and at different pH values (2.0-6.0). Adsorption behavior of heavy metal ions could be modeled using both the Langmuir and Freundlich isotherms. It was found that the adsorption capacity is highest at pH value of 6, whereas it decreases as the pH value decreases at temperature 25 degrees C +/- 1 degrees C for 240 min. The results obtained from the adsorption capacity experiments for Cu(II) and Zn(II) ions were 3.47-5.45 and 5.42-6.85 mg/g, respectively. The affinity order of polymers for both metal ions was observed as follows: SMAC > SAAC > MPS with MAH > MPS with SAH > MPS with PhAH. The maximum adsorption capacities of SMAC were 6.85mg/g for Zn(II) and 5.45 mg/g for Cu(II). (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 1192-1198, 2009Öğe Ultrasonic Properties of Polystyrene-Based Composites(WILEY, 2012) Oral, İmran; Güzel, Hatice; Ahmetli, GülnareIn this study, first the pure polystyrenes (PS) with different molecular weights (350 x 103 and 500 x 103) have been modified by the chemical modification with succinic anhydride (SA), maleic anhydride (MA), and phthalic anhydride (PhA) and then the polystyrene based composites (CPS) prepared by addition of modified polystyrenes (MPS) into pure PS (with the molecular weight of 230 x 103) in weight % ratios of 90 : 10, 80 : 20, and 70 : 30. Ultrasonic measurements were performed on PS/MPS blends of different weight percent of MPSs by use of pulse echo method with 5-MHz frequency at room temperature. Elastic properties namely; longitudinal modulus (L), Young's modulus (E), bulk modulus (K) and shear modulus (G), Poisson's ratio (mu), and acoustic impedance (Z) were calculated from the ultrasonic velocities values measured and densities values obtained experimentally. Atomic force microscopy (AFM) has been used for determining the microstructure of composites. The variations of these parameters with increasing MPSs weight percentage content in PS/MPS from 10 to 30 have been discussed.
