Yazar "Ahmetli, Gulnare" seçeneğine göre listele
Listeleniyor 1 - 20 / 35
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Adhesion and corrosion resistance properties of modified polystyrenes(JOHN WILEY & SONS INC, 2008) Ahmetli, Gulnare; Kaya, Ayse; Ozkececi, AysewIn this study, chemical modification of different molecular weight polystyrenes (PS) was researched with various functional group modificators: epichlorohydrin, maleic, and acetic anhydrides, in one stage and in the medium of BF3O(C2H5)(2) cationic catalyst. It was determined that the amounts of the functional groups, bound to the structure of the polymer, have been changed depending on the molecular weight of the PS used and more functional groups have been bonded to the lower molecular weight PS. It is stated that the adhesion properties and corrosion resistance of the modified PS on metal surface have been changed depending on the molecular weight of PS and the amount of the functional groups bound to the aromatic ring of the polymer. Various functional groups bound to the aromatic ring of the PS and their amounts were determined by spectral and chemical analysis methods. (c) 2007 Wiley Periodicals, Inc.Öğe Adhesive and Anticorrosive Polymeric Coatings Obtained From Modified Industrial Waste Oligostyrenes(Elsevier Science Sa, 2006) Ahmetli, Gulnare; Şen, Nejdet; Pehlivan, Erol; Durak, SancaktarIn this study, as a continuation of our previous studies on the chemical modification of different molecular weight polystyrenes (PS) with polyfunctionalized modifiers by using cationic catalyst, industrial waste oligostyrenes (IWOS) were used as raw material. These oligostyrenes are formed as waste material in the rectification of styrene, used for the production of PS in industry, and they cause environmental pollution. Chemical modification of these waste oligomers (IWOS) without waste residence was carried out with polyfunctional modifiers such as maleic (MA) and acetic anhydrides (AA) by using (BF3O)-O-.(C2H5)(2) catalyst in a single stage. Upon modification, it was determined that a maximum amount of functional groups (-COOH group 130 mg KOH/g polymer and 18 mol% CH3CO-group) was bonded to the structure of the oligostyrenes. Adhesion properties, corrosion resistance and impact of the polymeric coatings on metal surface changed as a result of the amount and structure of the polyfunctional groups bound to the polymer structure. It was determined that the modified IWOS had higher adhesion properties; and it was more resistant to corrosion and impact. Therefore, more economical resistant polymeric coatings were obtained; and their application areas were located by using this waste as raw material in polymeric reactions. (c) 2005 Elsevier B.V. All rights reserved.Öğe Chemical and plasma surface modification of lignocellulose coconut waste for the preparation of advanced biobased composite materials(ELSEVIER SCI LTD, 2017) Kocaman, Suheyla; Karaman, Mustafa; Gursoy, Mehmet; Ahmetli, GulnareIn this study, surface-modified grinded coconut waste (CW) particles were used as bio-fillers to prepare polymeric composite materials with enhanced properties. Epoxy resin modified with acrylated and epoxidized soybean oil (AESO) was used as the polymer matrix. Two different strategies, namely chemical treatment and plasma enhanced chemical vapor deposition (PECVD) were utilized to modify the surface of CW particles for using them as compatible bio-fillers in composite preparation. Chemical modification involved the treatment of CW particles in a highly alkali NaOH solution, while PECVD modification involved coating of a thin film of hydrophobic poly(hexafluorobutyl acrylate) (PHFBA) around individual CW particle surfaces. Untreated and surface-modified CW particles were used in 10-50 wt% for preparation of epoxy composites. FTIR analysis was performed to study the effect of modification on the structures of particles and as-prepared composites. The composite morphologies were investigated by XRD and SE. TGA test was conducted to study the thermal behavior of the composites. Also, the effects of CW particle surface modification on the mechanical and water sorption properties of epoxy resin composites were investigated in detail. It was observed that PECVD-treated CW particles had much more positive effects on the thermal, mechanical, wettability and flammability properties of composites. (C) 2016 Elsevier Ltd. All rights reserved.Öğe Coating, mechanical and thermal properties of epoxy toluene oligomer modified epoxy resin/sepiolite composites(ELSEVIER SCIENCE SA, 2012) Ahmetli, Gulnare; Deveci, Huseyin; Soydal, Ulku; Seker, Asli; Kurbanli, RefikaIn this research, epoxy toluene oligomer (ETO) was synthesised from toluene and epichlorhydrin, which was used as co-matrix in 50 wt.% with commercial epoxy resin (ER). Its chemical structure was characterised with FTIR spectroscopy and chemical analyses. ETO was found as an effective flame retardant for ER. Modification of ER with ETO in 50 wt.% increased percentage elongation at break of neat ER about 67 times. The rigid filler used in epoxy polymer matrix was the modified and unmodified sepiolite. The appropriate sepiolite amount in all cases was determined to be 5 wt.%. Scanning electron microscopy (SEM) was used for characterisation of surface and cross sections of the composites to verify the results. Modification of sepiolite increases the T-5, T-10, and T-50 of neat ETO-ER by 10, 7, and 5 degrees C, respectively. Surface hardness and tensile strength of all composites were higher than those of neat ETO-ER polymer matrix. ETO-ER/modified sepiolite coating showed the best adhesion results and exhibited perfect resistance to 3% NaCl and 10% NaOH solutions. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.Öğe A Comparative Study on Waste Plastics Pyrolysis Liquid Products Quantity and Energy Recovery Potential(ELSEVIER SCIENCE BV, 2017) Sogancioglu, Merve; Ahmetli, Gulnare; Yel, EsraPlastics thermal processing is an important application for both energy recovery and feedstock recycling. In this study effects of type of plastic (HDPE, LDPE, PET, PP, PS), pyrolysis process temperature and plastic waste prewashing on pyrolysis liquid product (oil) fraction, its hydrocarbon (HC) contents and heat values were investigated. Caustic washing and batch-pyrolysis were applied by keeping pyrolysis heating rate and other conditions constant. Oil yields, C10-C40 HCs, heat values were measured and compared. HDPE type plastic wastes produced the highest oil yield while PET and PP produced the lowest yields. C10-C40 HC contents of pyrolysis oils were strongly affected from the pyrolysis temperatures and pre-washing process under identical pyrolysis conditions. The highest C10-C40 HCs were produced by HDPE pyrolysis. Statistical analysis indicated that the effect of pre-washing process on the pyrolysis oil heat value is significant for HDPE and PP type plastics. Pyrolysis temperature had almost no effects on oil heat values for washed PET and unwashed PS wastes, whereas for other plastic samples, as pyrolysis temperature increased oil heat values increased. HDPE, LDPE, PP and PS pyrolysis oils have higher calorific values than wood and some coal types. These refer to energy recovery from those types of plastics. (C) 2017 The Authors. Published by Elsevier LtdÖğe Corrosion and thermal characterization of styrene based copolymers(ELSEVIER SCIENCE SA, 2011) Ahmetli, Gulnare; Deveci, Huseyin; Altun, Ahmet; Kurbanli, RefikaFilms from copolymers with resistance to wear, corrosion and thermal degradation as well as other important functions have been applied in many fields. It is known that the introduction of anionic hydrophilic groups in the polymer enhances its adhesion to substrates and protective function. In the present work, copolymers of styrene with acrylic, methacrylic and itaconic acids were prepared by polymerization in toluene with benzoyl peroxide initiation (BPO) and have been tested as anticorrosive films. The copolymers were analyzed by FTIR and TGA methods. Polarizing microscope images were employed to characterize the anticorrosive properties of the formed films. All copolymers produced in this work show strong adhesion to the substrate. (C) 2010 Elsevier B.V. All rights reserved.Öğe Determining the Elastic Properties of Modified Polystyrenes by Sound Velocity Measurements(WILEY, 2011) Oral, Imran; Guzel, Hatice; Ahmetli, Gulnare; Gur, C. HakanThe effect of the binding of various polyfunctional groups to polystyrene's (PS's) aromatic ring on the elastic properties of the PS were investigated by an ultrasonic method. Various sets of samples were prepared by chemical modification of pure PSs having different molecular weights with SA, maleic anhydride, and phthalic anhydride. The ultrasonic wave velocities of modified PSs were measured with the pulse-echo method at room temperature by a computer-controlled analyzer and a digital oscilloscope. The values of the acoustic impedance, Poisson's ratio, and elasticity constants of the samples were calculated by the measured values of the densities and sound velocities. The longitudinal and shear wave velocities and the values of all elastic constants increased with chemical modification of the pure PS. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 3425-3432, 2011Öğe Determining the mechanical properties of epoxy resin (DGEBA) composites by ultrasonic velocity measurement(WILEY, 2013) Oral, Imran; Guzel, Hatice; Ahmetli, GulnareIn this study, the composites of diglycidyl ether of bisphenol A (DGEBA) epoxy resin that have been formed by mixing epoxy resin with allyl glycidyl ether (AGE) and 2,3-epoxypropyl methacrylate [glycidyl methacrylate (GMA)] were prepared in weight % ratios of 90 : 10, 80 : 20, and 70 : 30. A computer controlled analyzer with 35 MHz and a digital oscilloscope with 60 MHz were used for measuring the velocities of ultrasonic wave. The measurement of ultrasonic velocity carried out by pulse echo method at frequencies of 2.25 and 3.5 MHz at room temperature. The values of acoustic impedance (Z), Poisson ratio (mu), and coefficients of elasticity (L, G, K, E) of composites were calculated by values of densities and velocities that obtained. Thus, the effect of modificating epoxy resin (DGEBA) by AGE and GMA on mechanical properties of DGEBA was investigated using the ultrasonic method. Atomic force microscopy has been used for determining the microstructure of composites. By the results obtained from the investigation, it have been established that the longitudinal and shear ultrasonic wave velocities, and the values of all the elasticity constants of DGEBA were increased by modification with AGE and GMA. Also the most suitable combination ratio for the compound of DGEBA : AGE and DGEBA : GMA has been found as 80 : 20. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 127: 1667-1675, 2013Öğe Effect of Modification with Various Epoxide Compounds on Mechanical, Thermal, and Coating Properties of Epoxy Resin(HINDAWI LTD, 2016) Cerit, Alaaddin; Marti, Mustafa Esen; Soydal, Ulku; Kocaman, Suheyla; Ahmetli, GulnareEpoxy resin (ER) was modified with four different epoxide compounds, 4,5-epoxy-4-methyl-pentane-2-on (EMP), 3-phenyl-1,2-epoxypropane (PhEP), 1-chloro-2,3-epoxy-5-(chloromethyl)-5-hexene (CEH), and a fatty acid glycidyl ester (FAGE), to improve its chemical and physical properties. The effects of the addition and amount of these modifiers on mechanical, thermal, and coating properties were investigated. Atomic force microscopy was used to observe the changes obtained with the modification. The influence of the modifying agents on the curing process was monitored through FTIR spectroscopy. The curing degrees of ER and modified ERs (M-ERs) were found to be over 91%. The results showed that tensile strength of ER improved till 30% (wt.) with addition of the modifier content. Modification with EMP and PhEP remarkably enhanced the thermal stability of ER to be highly resistant to the corrosive media.Öğe Effect of Unsaturated Keto-Groups on Physico-Mechanical and Thermal Properties of Modified Polystyrene(WILEY-BLACKWELL, 2011) Cerit, Alaaddin; Ahmetli, Gulnare; Kurbanli, RefikaPolystyrene (PS), after polyolefins, is the most widespread polymer both in industry and daily life, successfully replacing some natural raw materials. In this study, as a serial of our previous study, modified polystyrene containing acetyl group (CH3CO-) was used as a raw material and condensation reaction was performed in basic medium with aliphatic saturated and unsaturated aldehydes. The structures of modified polystyrenes with unsaturated keto-groups were investigated by chemical and spectral (FTIR vs. H-1 NMR) analyses. The effect of the functional groups bound to the structure of the polymer on physicomechanical and thermal properties of modified polystyrene was investigated. As a result, condensation products of modified polystyrenes with crotonaldehyde and cinnamaldehyde had higher physicomechanical properties and were more stable against the thermal destruction at high temperatures. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 1193-1202, 2011Öğe Effects of functional groups on the thermal properties of modified polystyrene(JOHN WILEY & SONS INC, 2007) Ahmetli, Gulnare; Cerit, AlaaddinPolystyrene is, after polyolefins, the most widespread polymer in both industry and everyday life, successfully replacing some raw natural materials. In this study, the chemical modification of polystyrenes of different molecular weights was performed with various functional group modifiers (epichlorohydrin, maleic anhydride, and acetic anhydride) in one stage and in the medium of the cationic catalyst BF3.O(C2H5)(2) according to previous studies. The concentration of the functional groups bonded to the aromatic ring of the polymer as a result of the chemical modification of polystyrenes of different molecular weights depended on the molecular weight of the polymer, and more functional groups were bonded to lower molecular weight polystyrene. The effects of the functional groups bonded to the structure of the polymer on the thermal properties of modified polystyrene were investigated. The polystyrene that was modified by maleic anhydride was more stable against thermal destruction at high temperatures. (c) 2007 Wiley Periodicals, Inc.Öğe Epoxy composites based on inexpensive char filler obtained from plastic waste and natural resources(WILEY, 2013) Ahmetli, Gulnare; Kocaman, Suheyla; Ozaytekin, Ilkay; Bozkurt, PinarIn this study, plastic [polyethylene terephthalate (PET)] waste was recycled as raw material for the preparation of diglycidyl ether of bisphenol A-type epoxy composite materials. The other inexpensive fillers used to prepare the composites were wood shavings char and pine cone char (PCC), obtained from natural resources. The thermogravimetric analysis showed that plastic waste char (PWC) and PCC can significantly improve the thermal stability of neat epoxy resin at temperatures above 300 degrees C. The best thermal and electrical conductivity results were obtained with PWC. The residual weight of the composite with 30 wt% PWC was 69%. Surface hardness, Young's modulus, and tensile strength of the composites were higher than those with a pure epoxy polymer matrix. The composite morphology was characterized by X-ray diffraction and scanning electron microscopy. POLYM. COMPOS., 2013. (c) 2013 Society of Plastics EngineersÖğe Epoxy Composites based on Inexpensive Tire Waste Filler(AMER INST PHYSICS, 2014) Ahmetli, Gulnare; Gungor, Ahmet; Kocaman, SuheylaTire waste (TW) was recycled as raw material for the preparation of DGEBA-type epoxy composite materials. The effects of filler amount and epoxy type on the mechanical properties of the composites were investigated. Tensile strength and Young's modulus of the composites with NPEL were generally higher than composites with NPEF. The appropriate mass level for TW in both type composites was found to be 20 wt%. The equilibrium water sorption of NPEL/TW and NPEF/TW composites for 14-day immersion was determined as 0.10 % and 0.21 %, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used for characterization of the composites.Öğe Epoxy resin/polymer blends: Improvement of thermal and mechanical properties(WILEY-BLACKWELL, 2012) Ahmetli, Gulnare; Deveci, Huseyin; Soydal, Ulku; Gurler, Sevgi Pistil; Altun, AhmetFatty acid waste was recycled as raw material and utilized to synthesize epoxy (HP) or unsaturated ester group (OEE) containing polymers. The radicalic polymerization between the styrene and itaconic acid was carried out, too. Glycidyl ester of styrene-itaconic acid copolymer was obtained by esterification reaction with epichlorohydrin. The polymers were characterized by means of Fourier transform infrared spectroscopy and chemical analysis. The polymers were incorporated into diglycidyl ether of bisphenol A type commercial epoxy resin to prepare composites. The effects of polymer structure and amount on the physico-mechanical and thermal properties of epoxy were investigated. Surface hardness, tensile strength, percentage elongation and stress at maximum load of the composites were obtained higher than pure epoxy resin. The composites reinforced with bio-based polymers showed about 74.55243% increase in elastic modulus over the pure epoxy matrix. Obtained Young's modulus values were higher for composites with styrene-based polymers. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012Öğe Evaluation of sugar mill lime waste in biobased epoxy composites(WILEY, 2018) Soydal, Ulku; Marti, Mustafa Esen; Kocaman, Suheyla; Ahmetli, GulnareIn this study, precipitated calcium carbonate-lime waste (LW) from sugar beet production was recycled as a raw material for the preparation of composite materials. Epoxidized soybean oil (ESO) was used as a co-matrix in 50 wt% with bisphenol A-type epoxy resin (ER). The composites were prepared with LW in varied per cent values (10-50 wt%) using the casting technique. The morphology of the composites was characterized by X-ray diffraction and scanning electron microscopy. Effects of ESO and LW amounts on the mechanical and thermal properties of the composites were investigated. Modification with ESO remarkably enhanced the plasticity of the material, but decreased the curing degree about 2%. The modified ER shows about 13% increase in elongation at break over the pure epoxy matrix. Density and hardness of neat epoxy matrices were observed to increase with the LW content in the composite. Tensile strengths of all composites are higher than that obtained with neat epoxy. The thermogravimetric analyses show that ESO and LW significantly improve the thermal stability of neat ER at the temperatures above 300 degrees C. The best thermal results were obtained with the composites containing 40- and 50 wt% LW. The residual weights of the composites are higher than that of neat ER and ER-ESO, and increases with the increasing LW amount. The T-5,T- T-10 and T-50 data of the composites are higher than those of neat ER and ER-ESO. The water sorption values of the ER-ESO matrix composites are in the range of 1.0-2.9 wt%. POLYM. COMPOS., 39:924-935, 2018. (c) 2016 Society of Plastics EngineersÖğe Fe(II) adsorption onto natural polymers derived from low-grade lignites(WILEY-BLACKWELL, 2007) Tarlan, Esra; Ahmetli, GulnareIn comparison with conventional chemical treatment methods for Fe(II) ions, adsorption and ion exchange are considered more easily applicable and economical, depending on the material used. Polymeric rnaterials are the examples used in these commonly applied removal processes. In this study, the adsorption of Fe(II) ions from aqueous solutions onto two different natural polymers, insoluble humic acids (IHAs) extracted from low-grade lignites from Beysehir and Ermenek (in the central Anatolia region, Konya, Turkey), was investigated. The IHAs were synthesized through a series of acid-base reactions, and the obtained precipitates were chemically stable and had about 40% humic matter together with functional carboxyl and hydroxyl groups. The effects of the time and initial metal concentration on the effectiveness of the IHAs for Fe(II) adsorption were determined through batch experiments; the adsorption isotherms and capacities were calculated. The IHAs were effective, with capacities of 59 mg/g for the Beysehir IHA and 57 mg/g for the Ermenek IHA, for Fe removal under neutral pH conditions. The adsorption followed mainly a Freundlich isotherm for both IHAs, and the calculated adsorption rates were 0.86 for the Beysehir IHA and 0.81 for the Ermenek IHA. This indicated that the effectiveness of the Beysehir IHA was slightly higher than that of the Ermenek IHA. The results confirmed the real possibility of the practical application of IHAs for the separation of Fe(II) in aqueous systems. (C) 2007 Wiley Periodicals, Inc.Öğe The Influence of Semiconductive Binary Sb2S3-Yb3S4 System on Electrical Conductivity Property of Epoxy Composites(AMER INST PHYSICS, 2014) Soydal, Ulku; Ahmetli, Gulnare; Kocaman, SuheylaThe purpose of this study is to develop the semiconductive composites. Semiconducting glass (SG) binary system Sb2S3-Yb3S4 in mole ratio 1:1 was synthesized and was doped with I-2. Next, electrically conductive DGEBA-type epoxy resin (ER)/SG-filled composites and epoxy toluene oligomer (ETO) modified epoxy resin-SG filled composites were developed with 3-10 wt. % of fillers and characterized. As a result, the effects of the modifier and amount of semiconductive filler on the electrical properties of commercial epoxy resin were examined. Percolation concentration was 7 wt. % for all composites. For the SG-reinforced composites, the dispersion of the fillers is investigated by X-ray diffraction (XRD) and by scanning electron microscopy (SEM).Öğe The influence of semiconductive binary systems on electrical conductivity, mechanical, and thermal properties of epoxy composites(WILEY, 2018) Soydal, Ulku; Ahmetli, GulnareThe purpose of this study is to develop epoxy composites with improved mechanical, thermal, and electrical properties. Semiconducting glass (SG) binary systems such as As2S3-TlS and As2Se3-TlS were synthesized in various mole ratios (1:1 and 1:3). Electrically conductive DGEBA-type epoxy-SG-filled composites were developed containing 1-15 wt% of fillers and characterized by X-ray diffraction and scanning electron microscopy techniques. As a result, the effects of the type and amount of semiconductive filler on the mechanical, thermal, and electrical properties of commercial epoxy resins (ERs) were examined. It was found that I-2 doping of the filler significantly increased the electrical conductivity of the composites up to 10(-3) S cm(-1). Percolation concentrations were found to be 7 wt% for all composites studied. The maximum tensile strength changed in the range of 86-114 MPa was obtained with 5-10 wt% of SG particles. In addition, the thermal behavior and stability of the epoxy composites were studied using thermogravimetric analysis. The incorporation of SG particles increased the 10% decomposition temperature of neat epoxy by 5 degrees C-35 degrees C. ER/SG coatings showed the best adhesion results and perfect resistance to 3% NaCl, 3% HCl, and 5% NaOH solutions. POLYM. COMPOS., 39:681-690, 2018. (c) 2016 Society of Plastics EngineersÖğe Investigation of synthesis of copolymers from the waste products of industrial oil refinement having adhesion properties and strength to the thermal destruction(SPRINGER/PLENUM PUBLISHERS, 2006) Yazicigil, Zafer; Ahmetli, Gulnare; Kara, Huseyin; Kocak, AhmetIn this study, the waste products of industrial vegetable oil refinement were transformed into the glycidyl ester for preventing the effects of them to the environment, the ways for evaluating them in polymer chemistry were investigated, copolymers having high adhesion property and strength to the thermal destruction were synthesized and the area of their usage was determined. For this reason, the waste product of sunflower oil refination as a vegetable oil in the industry; soap stock (SS) was converted to the unsaturated glycidyl esters by the interaction with epichlorohidrine in the alkaline medium. After that the copolymerization of synthesized unsaturated glycidyl esters and the other waste product of oil refinement fatty acid (FA) with styrene in the radicalic initiator medium were investigated and copolymers that have high strength to the thermal destruction and adhesion property were synthesized. From the results of TGA and DTA analysis, it was determined that synthesized copolymers have low loss of weight at high temperature. The structures of copolymers were fixed by spectral and chemical analysis methods.Öğe Investigation of the Effect of Polystyrene (PS) Waste Washing Process and Pyrolysis Temperature on (PS) Pyrolysis Product Quality(ELSEVIER SCIENCE BV, 2017) Sogancioglu, Merve; Yel, Esra; Ahmetli, GulnarePyrolysis has been proposed as a viable processing route for recovering the organic compounds from polystyrene (PS) plastic wastes as fuels and chemical feedstock. In this study, PS plastic wastes were collected; some portion of them was washed in field-simulated laboratory scale system. Both washed and unwashed PS plastic waste samples were pyrolyzed at fixed bed reactor pyrolysis equipment. The pyrolysis process has been applied at 300, 400, 500, 600 and 700 degrees C with 5 degrees C/min heating rate. The effect of pyrolysis temperature and plastic washing process on the pyrolysis yields and solid, oil and gas products quality were investigated. The solid products (char) were characterized by FTIR and SEM. Oil and gas products were analyzed by gas chromatography coupled with a mass spectrometry (GC-MS). The heat values were determined using an automatic calorimetric bomb. Pyrolysis oil products composed of heavy hydrocarbons (C10-C40). Heating values were found between 4300-4800 kCal. Pyrolysis gases of both wased and unwashed PS mainly contain gas samples contain pentene, pentane, hexane, benzene, heptane, toluene, octane, ethylbenzene and styrene. Each of these components has potential for use as fuel or as raw materials for various industrial processes after proper separation process. (C) 2017 The Authors. Published by Elsevier Ltd
