- Turkey
Memet Kahraman
Marmara University, CHEMISTRY, Faculty Member
Acrylonitrile butadiene styrene ( ABS) is a hard and light polymeric material widely used in computer, electronics, automotive and construction industry. In this study, alkoxy silane terminated urethane acrylate functional oligomer was... more
Acrylonitrile butadiene styrene ( ABS) is a hard and light polymeric material widely used in computer, electronics, automotive and construction industry. In this study, alkoxy silane terminated urethane acrylate functional oligomer was synthesized from perfloro alcohol. Coronated ABS sheets were coated with the various formulations containing sol-gel mixture, acrylated resin including fluor and other reactive components. ABS sheets were cured by using UV-light. The performance of coatings was investigated by applying various physical tests on coated sheets.
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We focused on polyacrylonitrile (PAN)/huntite composites to reinforce the polymer prepared by adding different percentages (wt%) of huntite to PAN. The composites were characterized using thermogravimetric analysis, differential scanning... more
We focused on polyacrylonitrile (PAN)/huntite composites to reinforce the polymer prepared by adding different percentages (wt%) of huntite to PAN. The composites were characterized using thermogravimetric analysis, differential scanning calorimetry, fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy techniques. It was clearly seen that the composites of PAN/huntite have better thermal stability than pure PAN. The effect of the huntite adding to Polyacrylonitrile (PAN) on dc conductivity and dielectric constant was also investigated. Dc conductivity values were increased with increasing temperature. Activation energy values were calculated depending on huntite contents in PAN. Relative dielectric constant values varied in the range of 16.5–21.2 at room temperature at 100 kHz frequency depending on huntite concentrations. All the electrical measurements were performed in dark and vacuum ambient between the temperatures of 295 and 523 K. Dielectric measur...
In this study, alpha-amylase was covalently immobilized on modified polyimide materials. Polyimide (PI) was prepared with pyromellitic dianhydride (PMDA) and 4,4'-oxydianline (4,4'-ODA) in the solution of N,N-dimethylformamide... more
In this study, alpha-amylase was covalently immobilized on modified polyimide materials. Polyimide (PI) was prepared with pyromellitic dianhydride (PMDA) and 4,4'-oxydianline (4,4'-ODA) in the solution of N,N-dimethylformamide (DMF). Free amine groups on the surface of the polyimide membranes were generated by the amination reaction of polyimides with hexamethylenediamine (HMDA). Surface-aminated membranes were then subjected to enzyme immobilization. The morphology of the polymeric support was characterized by scanning electron microscopy (SEM). Chemical structure of PMDA-ODA PI membranes was characterized by FTIR. SEM and FTIR results showed that the enzyme was successfully covalently attached to the polymeric support. Immobilization efficiency and enzyme activity of alpha-amylase was examined at various pH values (3.0 - 8.0) and temperatures (15 - 80 degrees C). Immobilization yield was found to be 285.45 mg per gram for the modified polyimide films. Enzyme assays demonst...
The use of polymers is finding a significant place in development of sensors. Better selectivity and rapid measurements have been achieved by replacing classical sensor materials with functions of polymers. Several receptors have been... more
The use of polymers is finding a significant place in development of sensors. Better selectivity and rapid measurements have been achieved by replacing classical sensor materials with functions of polymers. Several receptors have been employed to detect glucose in fluorescence sensors, and these include enzymes such as glucose oxidase, glucose dehydrogenase and hexokinase/glucokinase, bacterial glucose-binding protein, and boronic acid derivatives. Boronic acid has a important role in the design of glucose sensors. The sensing membrane was prepared with p-Vinylphenylboronicacid (VPBA), Hydroxyethylmethacrylate (HEMA) and Poly(ethylene glycol) diacrylate (PEG-DA). The membran is capable of determining glucose between 0.1 ppm and 0.7 ppm. It can be completely regenerated by using distilled water. The sensor performance characteristics such as response time, dynamic working range and sensitivity were reported. The optical sensor was stable, cost effective, easy to prepare, rapid and si...
ABSTRACT Poly(vinyl alcohol)/maleic anhydride/acryloyl thioamide monomer (PVA/MA/ATM) nanofiber membranes (NFm) were synthesized by a combination of UV radiation and an electrospinning technique. The PVA/MA/ATM NFm were characterized by... more
ABSTRACT Poly(vinyl alcohol)/maleic anhydride/acryloyl thioamide monomer (PVA/MA/ATM) nanofiber membranes (NFm) were synthesized by a combination of UV radiation and an electrospinning technique. The PVA/MA/ATM NFm were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Brunauer–Emmert–Teller (BET) analysis, scanning electron microscopy (SEM), and energy dispersion spectrometry (EDS). These membranes were used for adsorption–desorption of platinum (Pt(IV)) and palladium (Pd(II)) from a fire assay (FA) leaching waste solution, and the effect of process parameters such as pH of solution, contact time, NFm dosage, temperature, and adsorption isotherms and kinetics studies on the recovery of Pt(IV) and Pd(II) from the waste solution were investigated. The adsorption equilibrium data fit better using the Langmuir model than the Freundlich model. Maximum adsorption capacities, Q max, at 45 °C were found to be 69.93 and 112.36 mg/g for Pt(IV) and Pd(II), respectively. The activation energies (E a) of Pt(IV) and Pd(II) were 27.90 and 20.29 kJ/mol, respectively. The best desorption reagent was a 1.0 M HCl–1.0 M thiourea (TU) solution for both Pd(II) and Pt(IV). Reusability studies showed that the adsorption capacity can remain up to 90 % after five times of usage. This study provides a promising NFm with an effective adsorption property for Pt(IV) and Pd(II) ions.
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ABSTRACT In this study, first, polyethyleneimine was acrylated and mixed with polyvinyl alcohol solution to prepare photo-crosslinked polyethyleneimine (PEI)-based nanofibers by utilizing ultraviolet and electrospinning technique at the... more
ABSTRACT In this study, first, polyethyleneimine was acrylated and mixed with polyvinyl alcohol solution to prepare photo-crosslinked polyethyleneimine (PEI)-based nanofibers by utilizing ultraviolet and electrospinning technique at the same time. For CO2 permeability testing, same formulations were prepared by using solvent casting technique and exposed to ultraviolet light to have polyethyleneimine-based membrane films. The chemical structures of the nanofibers were characterized by Fourier transform infrared spectroscopy. The thermal properties of nanofibers were examined by thermal gravimetric analysis and differential scanning calorimeter. The morphology of nanofibers was investigated by scanning electron microscopy. CO2 permeabilities of samples were also measured. Copyright © 2015 John Wiley & Sons, Ltd.
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ABSTRACT Recently, 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)... more
ABSTRACT Recently, 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 3,3′, 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. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers
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ABSTRACT In this study, a novel three functional chain extender (TATATRIOL) was synthesized from the reaction of 1,3,5-tri(prop-2-en-1-yl)-1,3,5-triazinane-2,4,6-trione (TATA) with 2-sulfanylethanol. Then new thermoplastic polyurethanes... more
ABSTRACT In this study, a novel three functional chain extender (TATATRIOL) was synthesized from the reaction of 1,3,5-tri(prop-2-en-1-yl)-1,3,5-triazinane-2,4,6-trione (TATA) with 2-sulfanylethanol. Then new thermoplastic polyurethanes (TPUs) were synthesized by a one-step bulk polymerization from the reaction of 1,1′-methanediylbis(4-isocyanatocyclohexane) (H12MDI), a poly(ethylene adipate) based polyester polyol and a chain extender. Butane-1,4-diol (BD) and the newly synthesized monomer, TATATRIOL, were used as chain extenders. The effects of TATATRIOL on the properties of the TPU were investigated and compared to those of the TPU prepared with BD. The TPUs which derived from the sulfur containing chain extender displayed lower modulus and high elongation at break values than the analogous TPUs derived from BD. Moreover sulfur containing TPUs exhibited higher thermal stability.
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ABSTRACT In this study, we prepared photo-crosslinked modified HAP (hydroxy apatite)/polyvinyl alcohol (PVA) composite nanofiber scaffold for cell growth applications. HAP was synthesized and then modified with 4-vinylbenzene boronic acid... more
ABSTRACT In this study, we prepared photo-crosslinked modified HAP (hydroxy apatite)/polyvinyl alcohol (PVA) composite nanofiber scaffold for cell growth applications. HAP was synthesized and then modified with 4-vinylbenzene boronic acid (VBBA) to obtain 4-VBBA-HAP. By means of the simultaneous UV electrospinning technique 4-VBBA-HAP/PVA composite was obtained. The structure and morphology of electrospun membranes were investigated by scanning electron microscopy) and Fourier transform infrared spectroscopy technique. Nanofibers were treated with collagen solution via the spraying method. For the cell culture applications ECV304 and SAOS cells were seeded on the chosen electrospun fibrous scaffolds.
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ABSTRACT The aim of this study was to improve thermal stability, mechanical, and surface properties of bisphenol A dicyanate ester (BADCy) with the addition of bisphenol P dicyanate ester (BPDCy) and colemanite. The cyanate esters (BADCy... more
ABSTRACT The aim of this study was to improve thermal stability, mechanical, and surface properties of bisphenol A dicyanate ester (BADCy) with the addition of bisphenol P dicyanate ester (BPDCy) and colemanite. The cyanate esters (BADCy and BPDCy) were prepared from diphenol compound (bisphenol A or bisphenol P) and cyanogen bromide in the presence of triethylamine. The chemical structure of the synthesized cyanate esters was investigated by fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy (1H-NMR and 13C-NMR) techniques. The cyanate esters/colemanite composites having various ratios of BADCy, BPDCy, and colemanite were prepared. Thermal stability of the samples was evaluated by thermogravimetric analysis and differential scanning calorimetry. The samples were characterized with the following analyses: gel content, water absorption capacity, and stress-strain test. Hydrophobicity 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. Finally, the obtained results prove that the prepared composites have good thermal, mechanical, and surface properties and that they can be used in many applications such as the electronic devices, materials engineering, and other emergent.
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ABSTRACT In this study, octyltriphenylphosphonium bromide [OTPP-Br] was prepared from the reaction of triphenylphosphine and 1 -bromooctane. The modification of clay was done by ion exchange reaction using OTPP-Br in water medium.... more
ABSTRACT In this study, octyltriphenylphosphonium bromide [OTPP-Br] was prepared from the reaction of triphenylphosphine and 1 -bromooctane. The modification of clay was done by ion exchange reaction using OTPP-Br in water medium. Poly(amic acid) was prepared from the reaction of 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-Oxydianiline (ODA). Polyimide(PI)/clay hybrids were prepared by blending of poly(amic acid) and organically modified clay as a type of layered clays. The morphology of the Polyimide/ phosphonium modified clay hybrids was characterized by scanning electron microscopy (SEM). Chemical structures of polyimide and Polyimide/ phosphonium modified clay hybrids were characterized by FTIR. SEM and FTIR results showed that the Polyimide/ phosphonium modified clay hybrids were successfully prepared. Thermal properties of the Polyimide/ phosphonium modified clay hybrids were characterized by thermogravimetric analysis (TGA).
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ABSTRACT In this study, a novel route to synthesize polyimide (PI)/phosphorylated nanodiamond films with improved thermal and mechanical properties was developed. Surface phosphorylation of nano-diamond was performed in dichloromethane.... more
ABSTRACT In this study, a novel route to synthesize polyimide (PI)/phosphorylated nanodiamond films with improved thermal and mechanical properties was developed. Surface phosphorylation of nano-diamond was performed in dichloromethane. Phosphorylation dramatically enhanced the thermal stability of nano-diamond. Poly(amic acid) (PAA), which is the precursor of PI, was successfully synthesized with 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-oxydianiline (4,4'-ODA) in the solution of N,N- dimethylformamide (DMF). Pure BTDA-ODA polyimide films and phosphorylated nanodiamond containing BTDA-ODA PI films were prepared. The PAA displayed good compatibility with phosphorylated nano-diamond. The morphology of the polyimide (PI)/phosphorylated nano-diamond was characterized by scanning electron microscopy (SEM). Chemical structure of polyimide and polyimide (PI)/phosphorylated nano-diamond was characterized by FTIR. SEM and FTIR results showed that the phosphorylated nano-diamond was successfully prepared. Thermal properties of the polyimide (PI)/phosphorylated nanodiamond was characterized by thermogravimetric analysis (TGA). TGA results showed that the thermal stability of (PI)/phosphorylated nano-diamond film was increased.
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ABSTRACT In this study, fluorine-doped photocurable hybrid coatings were prepared by combining UV-curing technology with an anhydrous sol–gel method. First, methacryloxymethyl triethoxysilane (MEMO) was hydrolyzed via an anhydrous sol–gel... more
ABSTRACT In this study, fluorine-doped photocurable hybrid coatings were prepared by combining UV-curing technology with an anhydrous sol–gel method. First, methacryloxymethyl triethoxysilane (MEMO) was hydrolyzed via an anhydrous sol–gel process. Then MEMO was mixed with acrylic oligomers and predetermined amounts of fluoroacrylate resin. UV curable hybrid coatings were applied on corona-treated plexiglass substrates. 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. It was found that the optical transmittance of the coatings was higher than 95%. The surface morphology of the hybrid films was characterized by scanning electron microscopy (SEM). The chemical composition of the surface of the coatings was identified by energy dispersion spectrum (SEM–EDS) technique. SEM studies indicated that inorganic particles were dispersed homogenously throughout the organic matrix. J. VINYL ADDIT. TECHNOL., 2014. © 2014 Society of Plastics Engineers
ABSTRACT Modification 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... more
ABSTRACT Modification 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 was first modified with 3‐isocyanatopropyltriethoxysilane and then hydrolyzed prior to the coating preparation. The resulting precursor was mixed with norbornyl acrylate and hexanediol diacrylate, and highly roughened hydrophobic coatings were prepared with the aid of fluorinated/nonfluorinated alkoxysilane coupling agents and hydrophobic fumed nanosilica particles. The coatings were applied on borofloat glass. The addition of fluorine and nanosilica showed a significant impact on the properties of the coatings. As the fluorine and nanosilica contents were increased in the formulations, flame retardancy and the contact angle values of the coatings increased. The surface roughness of the coatings increased with the addition of hydrophobic fumed nanosilica particles. Also, the relation between the surface energy and the contact angle values of the coatings was investigated. J. VINYL ADDIT. TECHNOL., 19:31–38, 2013. © 2013 Society of Plastics Engineers
ABSTRACT This work describes the preparation and characterization of a new thiol-ene hydrogel by photoinitiated polymerization of pentaerythritoltetrakis(3-mercaptopropionate) (Penta3MP4), acrylic acid (AAc) and poly(ethylene glycol)... more
ABSTRACT This work describes the preparation and characterization of a new thiol-ene hydrogel by photoinitiated polymerization of pentaerythritoltetrakis(3-mercaptopropionate) (Penta3MP4), acrylic acid (AAc) and poly(ethylene glycol) dimethacrylate (PEGDA) as monomers and photo initiator(2,2-dimethoxy-2-phenylacetophenon) for its use as adsorbent. The thiol-ene hydrogel was characterized by using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Real-Time Fourier Transform Infrared Spectroscopy (RT-FTIR), Scanning Electron Microscopy (SEM), Thermal Gravimetric Analyze (TGA) techniques; the swelling behavior and gelation ratio of hydrogel were also investigated. The adsorption capability of the hydrogel against Au(III) ions was investigated. The effects of pH, agitation time, initial metal ion concentration and different metal ions on adsorption capacity were examined. Equilibrium studies have been carried out to determine the capacity of the hydrogel for adsorption of Au(III) ions, Langmuir and Freundlich adsorption models were applied to describe the experimental isotherms and isotherms constants. Equilibrium data were found to fit very well with Langmuir model. The reusability of the hydrogel was also investigated and the preconcentration factor of the hydrogel was determined. The proposed method was applied to Dikili Geothermal Water and computer circuit board scrap. The analytical performance of the method was also determined.
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ABSTRACT The sensing membrane was prepared by photopolymerization of 4-vinylphenylboronicacid (VPBA), hydroxyethylmethacrylate (HEMA) and poly(ethylene glycol) diacrylate (PEG-DA). The membran is capable of determining glucose between... more
ABSTRACT The sensing membrane was prepared by photopolymerization of 4-vinylphenylboronicacid (VPBA), hydroxyethylmethacrylate (HEMA) and poly(ethylene glycol) diacrylate (PEG-DA). The membran is capable of determining glucose between 2.78 × 10−4 mM and 5.56 × 10−3 mM with a limit of detection of 0.89 × 10−5 mM, and limit of quantification 3.17 × 10−3 mM (n = 7). It can be completely regenerated by using distilled water. The sensor performance characteristics such as response time, dynamic working range and sensitivity were reported. The proposed sensor was then applied successfully for the determination of glucose in blood samples.The optical sensor was stable, cost effective, easy to prepare, rapid and simple for the determination of glucose.
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ABSTRACT α-amylase was covalently immobilized on functionalized polyimide (PI) membranes via glutaraldehyde (GA) activation. 3,3′,4,4′-Benzophenonetetracarboxylic acid dianhydride (BTDA) and 4,4′-oxydianline (4,4′-ODA) based polyimide... more
ABSTRACT α-amylase was covalently immobilized on functionalized polyimide (PI) membranes via glutaraldehyde (GA) activation. 3,3′,4,4′-Benzophenonetetracarboxylic acid dianhydride (BTDA) and 4,4′-oxydianline (4,4′-ODA) based polyimide membranes were obtained via thermal imidization. Free amine groups on the surface of the polyimide membranes were generated by the amination reaction of polyimides with hexamethylenediamine (HMDA). Surface-aminated membranes were subjected to enzyme immobilization after GA activation. Immobilization efficiency and enzyme activity of α-amylase was examined at various pH (3.0–8.0) and temperature (15–80°C). The storage stability and reusability of immobilized α-amylase were investigated. Immobilization yield was found as 359.53 mg per gram of modified polyimide films. Enzyme assays demonstrated that the immobilized enzyme exhibited better thermo stability than the free one. The storage stability and reusability improved by the immobilization on this enzyme support. Free enzyme lost its activity completely within 15 days. On the other hand, the immobilized enzyme retained 79.98% of its activity after 30 days. These results confirmed that α-amylase was successfully immobilized and gained more stable character compared to the free enzyme.
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ABSTRACT In this study, UV curable polypyrrole containing thiol–ene based composite films were prepared by the reaction between Propoxylated (2) neopentyl glycol diacrylate (SR 9003), Trimethylolpropane tris(3-mercaptopropionate),... more
ABSTRACT In this study, UV curable polypyrrole containing thiol–ene based composite films were prepared by the reaction between Propoxylated (2) neopentyl glycol diacrylate (SR 9003), Trimethylolpropane tris(3-mercaptopropionate), (3-mercaptopropyl)trimethoxysilane, 1-vinyl-2-pyrrolidinone and polypyrrole. FT-IR was used to confirm the formation of the composites. Thermal stability of the samples was evaluated by thermogravimetric analysis (TGA). The samples were characterized with the following analysis; gel content, water absorption capacity. Hydrophobicity of the samples was determined by the contact angle measurements. Direct current (dc) conductivity measurements of samples were performed depending on polypyrrole content in the composites at room temperature. Capacitance measurements (40 Hz–100 kHz) of the samples were performed in the temperature range of 295–378 K. Dc conductivity and capacitance values of the samples were measured in vacuum in dark. Dc conductivity measurements revealed that dc conductivity values increased with increasing polypyrrole content. Dielectric measurements revealed that dielectric constant of the samples increased with increasing temperature and decreased with increasing frequency. It is also observed that dielectric constant of the samples decreased with increasing polypyrrole content.Graphical abstractKeywordsUV curingThiol–enePolypyrroleThermal propertiesDielectric properties
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ABSTRACT The aim of this study was to improve thermal conductivity, thermal stability, and mechanical properties of bisphenol A dicyanate ester with the addition of nanodiamond. Cyanate ester/nanodiamond composites containing various... more
ABSTRACT The aim of this study was to improve thermal conductivity, thermal stability, and mechanical properties of bisphenol A dicyanate ester with the addition of nanodiamond. Cyanate ester/nanodiamond composites containing various ratios of nanodiamond were prepared. Thermal stability and thermal conductivity of the samples were evaluated by thermogravimetric analysis, differential scanning calorimetry, and laser flash method, respectively. The samples were characterized with the analysis such as gel content, water absorption capacity, and stress–strain test. Hydrophobicity of the samples was determined by contact angle measurements. Moreover, the surface morphology of the samples was investigated by a scanning electron microscopy. The obtained results prove that the cyanate ester/nanodiamond composites have good thermal and mechanical properties and can be used in many applications such as the electronic devices, materials engineering, and other emergent. Copyright © 2014 John Wiley & Sons, Ltd.
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ABSTRACT The aim of this study was to improve thermal stability and dielectric properties of polypyrrole (PPy) by adding hexagonal boron nitride (h-BN). PPy was synthesized, and PPy/h-BN nanocomposites were prepared by adding various... more
ABSTRACT The aim of this study was to improve thermal stability and dielectric properties of polypyrrole (PPy) by adding hexagonal boron nitride (h-BN). PPy was synthesized, and PPy/h-BN nanocomposites were prepared by adding various proportions of h-BN to PPy. The chemical structures of the samples were investigated by Fourier transform infrared spectroscopy. Thermal properties of the nanocomposites were determined by thermogravimetric analysis and differential scanning calorimetry. X-ray diffraction analysis of the samples was carried out. The surface morphologies of the samples were investigated by a scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The obtained results prove that the nanocomposite system is more thermally stable than the pure PPy. Dielectric measurements revealed that the dielectric constant of the pellets increased with increasing temperature and decreased with increasing frequency. It is also observed that the dielectric constant of the pellets decreased with increasing nano-hBN content (between 1 and 4 wt%).
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ABSTRACT In 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... more
ABSTRACT In 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., 2014. © 2014 Society of Plastics Engineers
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ABSTRACT A series of UV-curable B/F/Si-containing hybrid coatings was prepared by the anhydrous sol-gel technique. The chemical structure of the coatings was characterized by FTIR, RTIR, and 1HNMR techniques. The UV-curable coatings were... more
ABSTRACT A series of UV-curable B/F/Si-containing hybrid coatings was prepared by the anhydrous sol-gel technique. The chemical structure of the coatings was characterized by FTIR, RTIR, and 1HNMR techniques. The UV-curable coatings were applied to polycarbonate substrates. The physical and mechanical properties of the UV-cured coatings, such as pendulum hardness, pencil hardness, contact angle, gel content, MEK rubbing test values, tensile strength, abrasion resistance, and gloss, were examined. Thermal gravimetric analysis (TGA) was done. The relative flammability of the hybrid coatings was tested by the limiting oxygen index (LOI) method. Results of all analyses conducted on the free films and coatings are discussed. J. VINYL ADDIT. TECHNOL., 19:39–46, 2013. © 2013 Society of Plastics Engineers
ABSTRACT The aim of this study was to improve thermal stability and surface properties of bisphenol A dicyanate ester (BADCy) by adding bisphenol S dicyanate ester (BSDCy) and Ba(BO2)2. Bisphenol S and bisphenol A cyanate ester/barium... more
ABSTRACT The aim of this study was to improve thermal stability and surface properties of bisphenol A dicyanate ester (BADCy) by adding bisphenol S dicyanate ester (BSDCy) and Ba(BO2)2. Bisphenol S and bisphenol A cyanate ester/barium metaborate composites having various ratios of BADCy, BSDCy, and Ba(BO2)2 were prepared. Thermal stability of the samples was evaluated by thermogravimetric analysis and differential scanning calorimetry. Hydrophobicity of the samples was determined by the contact angle measurements. The samples were characterized with the following analysis; gel content, water absorption capacity. Moreover, the surface morphology of the samples was investigated by a scanning electron microscopy. The obtained results prove that the cyanate ester containing sulfonyl/Ba(BO2)2 composites have good thermal and surface properties and they can be used in many applications such as electronic devices, materials engineering, and other emergent. POLYM. COMPOS., 2014. © 2014 Society of Plastics Engineers
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ABSTRACT A polyacrylonitrile (PAN)-based carbon fiber-silicon carbide core-shell hybrid (SiC/PAN-CF) was prepared by carbothermal reduction of SiO2/PAN-CF, which was obtained by dip coating a SiO2 sol on the surface of PAN-CF. The surface... more
ABSTRACT A polyacrylonitrile (PAN)-based carbon fiber-silicon carbide core-shell hybrid (SiC/PAN-CF) was prepared by carbothermal reduction of SiO2/PAN-CF, which was obtained by dip coating a SiO2 sol on the surface of PAN-CF. The surface of the PAN-CF was uniformly covered with the SiC, and the decomposition temperature of SiC/PAN-CF was higher than that of the uncoated PAN-CF. In addition, the thermal conductivity of epoxy composites consisting of PAN-CF or SiC/PAN-CF was measured using a laser flash method. At a 80 wt% filler loading, the thermal conductivity of SiC/PAN-CF-epoxy composite was found to be 0.750 W/mK, which is 2 times higher than that of the PAN-CF-epoxy composite and approximately 3.5 times greater than that of unmodified epoxy resin. Furthermore, the thermal conductivity of SiC/PAN-CF-epoxy composite increased with increasing carbothermal reduction time. This increased thermal conductivity is due to improving the specific surface area and wettability with epoxy matrix, thus resulting in an improved the interfacial adhesion with epoxy matrix.
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ABSTRACT In this study, photo cross-linked thiophene based nanofibers were prepared by utilizing UV and electrospinning technique at the same time. For this purpose 3-(ethyl acrylate) thiophene (AC-TP) and 3-( ethyl maleate) thiophene... more
ABSTRACT In this study, photo cross-linked thiophene based nanofibers were prepared by utilizing UV and electrospinning technique at the same time. For this purpose 3-(ethyl acrylate) thiophene (AC-TP) and 3-( ethyl maleate) thiophene (MA-TP) were synthesized and polymerized to have Poly[3-(ethyl acrylate) thiophene] (P(AC-TP)) and Poly[3-(ethyl maleate) thiophene] (P(MA-TP)). The chemical structures of the synthesized monomers and polymers were characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (NMR) techniques. P(AC-TP) and P(MA-TP) polymers were mixed with PVA solutions. By utilizing UV and electrospinning technique at the same time, photo cross-linked thiophene based nanofibers were prepared. The thermal properties of nanofibers and polymers were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology of nanofibers was investigated by scanning electron microscopy (SEM). The results showed that as the amount of conducting polymer increased in the formulations, the average diameter of prepared nanofibers decreased.
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Page 1. RESEARCH ARTICLE Desizing of untreated cotton fabric with the conventional and ultrasonic bath procedures by immobilized and native a-amylase Burcu Yılmaz S¸ahinbaskan1 and Memet Vezir Kahraman2 1 Faculty ...
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ABSTRACT In this present work, we reported the adsorption and recovery studies of a P(Penta3MP4/PEG-DA/HEMA) thiol-ene based hydrogel. Real-time infrared spectroscopy technique was used to identify the photopolymerization kinetics of... more
ABSTRACT In this present work, we reported the adsorption and recovery studies of a P(Penta3MP4/PEG-DA/HEMA) thiol-ene based hydrogel. Real-time infrared spectroscopy technique was used to identify the photopolymerization kinetics of thiol-ene based formulations. The chemical composition and surface morphology of hydrogels were also characterized. The influence of the adsorption conditions such as pH, hydrogel formulations, contact time, initial metal ion concentration, and foreign metal ions on the metal ion binding capacity of hydrogel, were tested. Both the Langmuir and Freundlich isotherm models were applied to the method. The reusability of the hydrogels and the usability of the hydrogels for preconcentration studies were also investigated. The analytical parameters of the method were calculated and the recovery of silver ions from waste radiographic films was also applied to the hydrogels.
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ABSTRACT The aim of this study was to improve hybrid dual-curable cyanate ester/boron phosphate composites via sequential thiol-ene photopolymerization and thermal polymerization for high performance applications such as aerospace and... more
ABSTRACT The aim of this study was to improve hybrid dual-curable cyanate ester/boron phosphate composites via sequential thiol-ene photopolymerization and thermal polymerization for high performance applications such as aerospace and electronic devices. A novel 2,2'-diallylbisphenol A dicyanate ester (DA-BADCy) which is the allyl group containing cyanate ester was synthesized and characterized. DA-BADCy, silicon containing monofunctional thiol compound, trifunctional thiol compound and boron phosphate were cured using both ultraviolet (UV) and thermal methods. Using thiol-ene system, cyanate ester formulations, which are normally prepared at high temperatures, were prepared at room temperature. This study maintains ease of application for cyanate esters. Thermal stability, flammability and thermal conductivity of the samples were evaluated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), limiting oxygen index (LOI) and laser flash method, respectively. The samples were characterized with the following analysis; gel content, water absorption capacity and stress-strain test. Hydrophobicity of the samples was determined by the contact angle measurements. Moreover, the surface morphology of the samples was investigated by a scanning electron microscopy (SEM-EDS). The obtained results prove that the composites have good thermal and mechanical properties and with the help of easier preparation techniques, they can be used in many applications such as aerospace, electronic devices, materials engineering.
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ABSTRACT Alkyd resins are produced with reaction of oil or fatty oil, polyol and polyacid. Alkyd resins are commonly used in coating and paint industry due to ease of application in changing environmental conditions. Linseed oil based... more
ABSTRACT Alkyd resins are produced with reaction of oil or fatty oil, polyol and polyacid. Alkyd resins are commonly used in coating and paint industry due to ease of application in changing environmental conditions. Linseed oil based paints executed all requirements of technical properties, drying time, storage properties, simplicity in maintenance, appearance, economy, etc. In this study, linseed oil based alkyd resins having different oil contents were synthesized Paint formulations were prepared by mixing alkyd resin and various additives such as huntite, Aerosil R972, talc, titanium dioxide, dryer, wetting agent and anti-skinning agent. All formulations were applied on paper test plates and were dried at 30 °C. The obtained coatings were characterized by pencil hardness test, pendulum hardness test, chemical resistance test, cross-cut test, contact angle and gloss measurement. Also thermal and morphological properties were investigated by thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM) respectively. The thermal stability of the paint materials are improved with by increasing the amount of huntite and Aerosil R972 in the paint compositions.
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ABSTRACT The aim of this study was to improve thermal conductivity, thermal stability, and mechanical properties of bisphenol A dicyanate ester (BADCy) by adding bisphenol A dicyanate ester containing fluorine (F-BADCy) and nano diamond.... more
ABSTRACT The aim of this study was to improve thermal conductivity, thermal stability, and mechanical properties of bisphenol A dicyanate ester (BADCy) by adding bisphenol A dicyanate ester containing fluorine (F-BADCy) and nano diamond. The cyanate esters containing fluorine/nano diamond composites having various ratios of BADCy, F-BADCy, and nano diamond were prepared. Thermal stability and thermal conductivity of the samples were evaluated by thermogravimetric analysis, differential scanning calorimetry and laser flash method, respectively. The samples were characterized with the following analysis; gel content, water absorption capacity, and stress-strain test. Hydrophobicity of the samples was determined by the contact angle measurements. Moreover, the surface morphology of the samples was investigated by a scanning electron microscopy (SEM). The obtained results prove that the cyanate ester containing fluorine/nano diamond composites have good thermal and mechanical properties and they can be used in many applications such as electronic devices, materials engineering, and other emergent. POLYM. COMPOS., 34:1977–1985, 2013. © 2013 Society of Plastics Engineers
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ABSTRACT The present study investigated the possibility of preparing polyvinyl alcoholic (PVA) organic-inorganic hybrid nanofiber membranes by electrospinning with UV irradiation. To this end, PVA, PVA/SiO2 organic-inorganic hybrid... more
ABSTRACT The present study investigated the possibility of preparing polyvinyl alcoholic (PVA) organic-inorganic hybrid nanofiber membranes by electrospinning with UV irradiation. To this end, PVA, PVA/SiO2 organic-inorganic hybrid obtained with Geniosil (R) XL 33 as a SiO2 source, and imidazole-functionalized mesoporous PVA/SiO2/N=N nanofiber membranes were synthesized. These membranes were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric-differential thermal analysis, and Brunauer-Emmett-Teller analysis. According to results, fine polymeric nanofibers were obtained in the size range of 100-200 nm for pure PVA nanofibers and 150-250 nm for PVA/SiO2 hybrid nanofibers, while imidazole-functionalized PVA/SiO2 nanofibers were less than 100 nm. The membranes produced are suitable for use in various applications, including filtration and adsorption, in the biomedical and textile industries, among others.
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ABSTRACT The recognition and sensing of the biologically and environmentally important metal ions has emerged as a significant goal in the field of chemical sensors in recent years. Among the various analytical methods, fluorescence has... more
ABSTRACT The recognition and sensing of the biologically and environmentally important metal ions has emerged as a significant goal in the field of chemical sensors in recent years. Among the various analytical methods, fluorescence has been a powerful tool due to its simplicity, high detection limit and application to bio imaging.In this study, UV cured polymeric optical sensor for Au (III) ion based on a fluorescence membrane has been developed. The response characteristics of the sensor including dynamic range, pH effect and response time were systematically investigated. The influences of the conditions such as pH, response time on the metal ion binding capacity of membrane were also tested.
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Thiol-ene polymerization is a versatile tool for several applications. Here we report the preparation of epoxide groups containing thiol-ene photocurable polymeric support and the covalent immobilization of alpha-amylase onto these... more
Thiol-ene polymerization is a versatile tool for several applications. Here we report the preparation of epoxide groups containing thiol-ene photocurable polymeric support and the covalent immobilization of alpha-amylase onto these polymeric materials. The morphology of the polymeric support was characterized by scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) coupled with SEM was used to explore the chemical composition. The polymeric support and the immobilization of the enzyme were characterized by FTIR analysis. SEM-EDS and FTIR results showed that the enzyme was successfully covalently attached to the polymeric support. The immobilization efficiency and enzyme activity of alpha-amylase were examined at various pH (5.0-8.0) and temperature (30-80 degrees C) values. The storage stability and reusability of immobilized alpha-amylase were investigated. The immobilization yield was 276 +/- 1.6 mg per gram of polymeric support. Enzyme assays demonstrated that the immobilized enzyme exhibited better thermostability than the free one. The storage stability and reusability were improved by the immobilization on this enzyme support. Free enzyme lost its activity completely within 15 days. On the other hand, the immobilized enzyme retained 86.7% of its activity after 30 days. These results confirm that alpha-amylase was successfully immobilized and gained a more stable character compared with the free one.
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The aim of this study was to develop biodegradable, photo-polymerizable in situ gel-forming systems prepared from a fumaric acid monoethyl ester (FAME) modified poly(lactide-co-glycolide) (PLGA) co-polymer. By reacting lactide and... more
The aim of this study was to develop biodegradable, photo-polymerizable in situ gel-forming systems prepared from a fumaric acid monoethyl ester (FAME) modified poly(lactide-co-glycolide) (PLGA) co-polymer. By reacting lactide and glycolide in the presence of stannous octoate as a catalyst and 2-ethyl,2-hydroxymethyl 1,3-propanediol as an initiator, hydroxyl terminated branched PLGA was synthesized. Afterwards, at room temperature hydroxyl terminated branched PLGA was reacted with fumaric acid monoethyl ester (FAME). N,N'-dicyclohexylcarbodiimide and triethylamine were used as a coupling agent and catalyst, respectively. The gel percentage, equilibrium mass swelling, degradation profile and polymerization kinetics of the hydrogels were investigated. All of the results were influenced by the amount of FAME modified PLGA co-polymer. Biocompatibility of the hydrogels was examined by using MTT cytotoxicity assay. According to the results, hydrogels are biocompatible and cell viability percentage depends on the amount of PLGA co-polymer. While the amount was 15% in hydrogel composition, cell viability was 100%, but after increasing the PLGA co-polymer amount to 30% the viability reduced to 78%.