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Öğe Characterizations and properties of oligoazomethines (including CH3 and NO2 groups) char composites(ELSEVIER SCIENCE INC, 2013) Ozaytekin, IlkayIn this research, the oligomers were synthesized by the polycondensation of diamins (1,4-diamino-2-nitrobenzene and 2,5-diaminotoluene sulfate) with dialdehydes (terephtaldehyde 4,4'-diformylbiphenyl, bis(4-formylphenyl) ether and p-phenylene diacrolein). In this study, the oligoazomethines (OAMs) were studied using IR and UV-visible spectra and X-ray diffraction. The initial degradation temperatures (IDT) determined from TGA of OAMs were in the range of 225-270 degrees C indicating their good thermal stability. The conductivity measurements of OAMs were carried out with an electrometer using four-point probe technique. The highest conductivity increase among all the oligoazomethine/char composites was observed for the OAMs composites formed with 30% char ratio. (c) 2013 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.Öğe The Effect of Carboxylic Acid Group on Conductivity of the Aromatic Polyazomethines and Char Composites(WILEY, 2014) Ozaytekin, IlkayOne of the properties gained by COOH groups of polymer, exists in aromatic polyazomethine (PAM) in the main chain, is the increase in the conductivity. In this study, the PAMs including carboxylic acid in subgroups as condensation polymerization products were obtained. The electrical conductivity of the polymers was enhanced by many orders of magnitude by PAM. The carboxylic acid group increase the electrical conductivity in two ways are: (i) increasing chain flexibility and (ii) allowing movement of the charge carrier more easily along the chain. Additionally, in this study, the polymer composites were obtained using the carbon material (char) derived from the 400 degrees C pyrolysis of waste polyethylene terephthalates. It was observed that conductivity also increased due to char in the composites formed by the PAMs with char. The lowest E-g value of 0.55 eV was determined in poly-2-carboxyl-1,4-bis[(diphenylether)methylene]phenylenediamine/char composite. The structures of the obtained polymers were confirmed by FTIR, UV-vis, TGA,H-1 NMR, and EDX techniques. The molecular weight distribution parameters of the synthesized compounds were determined with the size exclusion chromatography. POLYM. COMPOS., 35:372-380, 2014. (c) 2013 Society of Plastics EngineersÖğe 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 Preparation of Epoxy Composites With CTAB-Modified BN and MWCNTs(WILEY-BLACKWELL, 2016) Ozaytekin, Ilkay; Turedi, Hamza Ercan; Ahmetli, GulnareIn this study, multi-walled carbon nanotubes (MWCNTs) and boron nitride (BN) were functionalized with cetyltrimethylammonium bromide (CTAB) at both pH 5.5 and pH 11. These MWCNT-CTAB and BN-CTAB particles used to prepare the composites were dispersed in a bisphenol A (DGEBA)-type epoxy resin (ER) system at room temperature. The TGA analysis showed that the BN composite can significantly improve the thermal stability of neat ER at temperatures above 400 degrees C. The curing degrees of the nanocomposites were calculated to be approximately the same values as neat ER using the Beer-Lambert law from FTIR spectra. The best electrical conductivity of the composites obtained was 3.10 x 10(-3) S/cm for ER/MWCNT-CTAB (pH 5.5). The surface hardness, Young's modulus, and tensile strength of the composites were examined. The surface hardness values of the ER/MWCNT-CTAB composites were higher than those of the other composites. The composite morphology was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). (C) 2015 Society of Plastics EngineersÖğe Synthesis and Characterization of PVA/Calix[4]arene Fibers(TAYLOR & FRANCIS INC, 2013) Kocyigit, Serhat; Tabakci, Mustafa; Ozaytekin, IlkayIn this study, both boron-doped and -undoped poly(vinyl alcohol)/Calix[4]arene fibers were prepared by using an electrospinning technique. Obtained fibers were characterized by FT-IR, DSC, and SEM techniques. The DSC results show that the degradation of the boron-doped fibers started at much higher temperatures. This result indicates the addition of boron increased the thermal stability of the fibers. SEM pictures show that both of the fiber samples are nonbeaded with diameters ranging from 0.5 to 1 mu m. The fiber diameters are not homogeneous and uniformly distributed for boron-undoped samples.Öğe Synthesis and characterization of thermally stable polymers (polybenzimidazoles)(WILEY-BLACKWELL, 2008) Ozaytekin, Ilkay; Karatas, IbrahimIn this study, an alternative synthesis of polybenzimidazoles was performed with aromatic hydroxamoyl chloride. In contrast to the literature, polybenzimidazoles were obtained through the reaction of hydroxamoyl chlorides with 3,3'-diaminobenzidine or 1,2,4,5-tetraaminobenzene. The characterization of the polymers was performed with Fourier transform infrared, (1)H-NMR, elemental analysis, LC mass spectrometry, and differential thermogravimetry/thermogravimetric analysis. Finally, the adhesion, corrosion resistance, and conducting properties of the synthesized polymers were examined. (C) 2008 Wiley Periodicals, Inc.Öğe Synthesis and Properties of Composites of Oligoazomethine with Char(WILEY, 2012) Ozaytekin, Ilkay; Kar, YakupConjugated aromatic oligo(azomethine) derivatives (oligo-AMs) were prepared by the condensation of terephtaldehyde 4,4'-diformylbiphenyl bis(4-formylphenyl) ether and p-phenylene diacrolein with 1,4-diaminobenzene at room temperature. The structures of the synthesized oligomers were characterized by FTIR, H-1 NMR, TGA-DTG, UV-vis absorption spectra, and elemental analyses. Additionally, in this study, the oligomer composites were obtained using the carbon material (char) derived from the 450 degrees C pyrolysis of waste polyethylene terephthalates. The conductivity measurements of the produced composites were determined at 24-h periods by doping with iodine vapor. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123:815-823, 2012
