Browsing by Subject "Thermal characterization"
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Item Thermal characterization of Ag and Ag + N ion implanted ultra-high molecular weight polyethylene (UHMWPE)(2007) Sokullu Urkac E.; Oztarhan A.; Tihminlioglu F.; Kaya N.; Ila D.; Muntele C.; Budak S.; Oks E.; Nikolaev A.; Ezdesir A.; Tek Z.Most of total hip joints are composed of ultra-high molecular weight polyethylene (UHMWPE ). However, as ultra-high molecular weight polyethylene is too stable in a body, wear debris may accumulate and cause biological response such as bone absorption and loosening of prosthesis. In this study, ultra-high molecular weight polyethylene samples were Ag and Ag + N hybrid ion implanted by using MEVVA ion implantation technique to improve its surface properties. Samples were implanted with a fluence of 1017 ion/cm2 and extraction voltage of 30 kV. Implanted and unimplanted samples were investigated by thermo-gravimetry analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), optical microscopy (OM) and contact Angle measurement. Thermal characterization results showed that the ion bombardment induced an increase in the % crystallinity, onset and termination degradation temperatures of UHMWPE. © 2007 Elsevier B.V. All rights reserved.Item New Poly(azomethine-urethane)s including melamine derivatives in the main chain: Synthesis and thermal characterization(John Wiley and Sons Inc., 2011) Kaya A.; Yäldäräm M.; Kamacä M.; Avcä A.Up to date, only a few kinds of poly (azomethine-urethane)s (PAMUs) derived from aromatic hydroxy compounds were obtained and studied with thermal degradation steps. Novel PAMUs were prepared using the hydroxy-functionalized Schiff bases derived from melamine and toluene-2,4-diisocyanate. Schiff base prepolymers were synthesized by the condensation reaction of melamine with 4-hydroxybenzaldehyde and 2-hydroxy-1-naphtaldehyde. Characterization was made by UV-Vis, FTIR, NMR, and SEC techniques. Thermal characterizations of the novel PAMUs were carried out by TG-DTA and DSC techniques. Thermal decomposition steps at various temperatures were also clarified and the physical changes of the synthesized PAMUs with exposing to the thermal degradation steps were displayed. © 2011 Wiley Periodicals, Inc.Item Synthesis and thermal characterization of novel poly(azomethine-urethane)s derived from azomethine containing phenol and polyphenol species(2011) Kaya I.; YIldIrIm M.; AvcI A.; KamacI M.Oligophenol-based poly(azomethine-urethane)s (PAMUs) were newly synthesized in two steps. At the first step, the prepolymers including the phenol and oligophenol based-Schiff bases were prepared by a condensation reaction of o-dianisidine with 4-hydroxybenzaldehyde/3-ethoxy-4-hydroxybenzaldehyde, and the polycondensation reactions of the corresponding Schiff bases in an aqueous alkaline media. At the second step, the PAMUs were obtained by copolymerization of the prepolymers with toluene-2,4-diisocyanate (TDI) under an argon atmosphere. The structures of the obtained compounds were confirmed by FTIR, UV-vis, 1H NMR, and 13C NMR, and size exclusion chromatography (SEC) techniques. The synthesized compounds were also characterized by TG-DTA and DSC analyses. Thermal decomposition steps at various temperatures were clarified by FTIR analyses of the degraded products. The physical changes to the synthesized PAMUs after exposing them to the thermal degradation steps are displayed. © 2011 The Polymer Society of Korea and Springer Netherlands.Item Fluorescence, thermal, electrochemical, and morphological properties of new poly(Urethane-İmide)s: Synthesis and characterization(Taylor and Francis Inc., 2014) Avci A.; Şirin K.New thermally stable poly(urethane-imide)s (PUIs) were synthesized to investigate aliphatic and aromatic group effects on various properties such as thermal stability and electrochemical properties. Thermal characterizations were carried out by TG-DTA and DSC techniques. TGA results showed that the PUIs derived from aromatic diisocyanates had relatively higher thermal stabilities as compared to the aliphatic diisocyanate. They have between 223-245°C onset temperature and above 37% char at 1000°C. Also, thermal degradation values show that PUIs have higher stability than conventional PU. DSC results showed that the new PUIs have Tg values between 134 and 138°C. Fluorescence measurements were performed using dimethyl sulfoxide solutions and also, the optimization of the concentrations maximal emission intensity was investigated in dimethyl sulfoxide. As a result, the remarkable properties related to the fluorescence and thermal measurements of the polymers were obtained. Therefore, these polymers could be used in various application fields because of the fluorescent and thermal properties. © Taylor & Francis Group, LLC.Item Synthesis, characterization, optical, and electrochemical properties of thermal stable novel poly(azomethine-ether)s(2014) Kaya I.; Avci A.; Kolcu F.; Çulhaoǧlu S.In this study, the novel Schiff base monomers were synthesized by condensation reactions. Then, these monomers were converted to poly(azomethine-ether)s by oxidative polycondensation (OP) reactions in an aqueous alkaline medium. The structural characterizations of compounds were carried out by FT-IR, NMR, and size exclusion chromatography (SEC). According to the SEC analysis, the calculated number-average molecular weight (M n), weight average molecular weight (Mw), and polydispersity index values of P-2 and P-4 were found to be 17,500 g mol -1, 24,400 g mol-1, and 1.39; and 18,700 g mol -1, 25,600 g mol-1, and 1.36, respectively. The HOMO-LUMO energy levels, electrochemical (), and optical (Eg) band gaps of polymers were calculated from cyclic voltammetry (CV) and UV-vis measurements, respectively. CV was used to determine the electrochemical oxidation-reduction characteristics of polymers. Thermal characterizations of compounds were made by using TG-DTA and DSC techniques. According to TG analysis, polymers with higher initial degradation temperatures (Ton) than those of their monomers indicate that the synthesized polyphenols have higher thermal stabilities than their monomer species. © 2013 Taylor & Francis.Item Thermal characterization of chicken feather/PLA biocomposites(Springer Netherlands, 2017) Özmen U.; Baba B.O.In this work, thermal properties of composites from chicken feather fiber (CFF) and polylactic acid (PLA) were investigated. CFF/PLA green composites were manufactured by extrusion and injection molding. Short and long fibers (3 and 20 mm) were used at different contents (2, 5 and 10 mass%). The effects of fiber concentration and fiber length on thermal properties of CFF/PLA composites were studied. Thermal properties of CFF/PLA composites were examined through differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and dynamic mechanical analysis (DMA). From the experiments, it was found that addition of CFF was effective to improve the thermal properties of PLA. The DSC results showed that heat flow increased with the increase in CFF content on the glass transition, on the crystallization temperature and on melting temperature. The TG results revealed that addition of CFF to PLA had positive effect on the thermal stability. In addition, the results of DMA experiments showed that the tan δ decreased with the increasing CFF content, indicating less damping and more elastic behavior in the composites. The results obtained from this study provide important information on the temperature-dependent properties of CFF/PLA and lead to new product development based on natural resources. © 2017, Akadémiai Kiadó, Budapest, Hungary.Item X-ray irradiated thermo- and radioluminescence, structural and thermal characterization of septarian (powder&bulk) from Madagascar(Elsevier B.V., 2018) Keskin İ.; Katı M.İ.; Türemiş M.; Gültekin S.; Üstün S.; Çetin A.; Kibar R.The luminescence properties of septarian have been investigated for the first time in this study, which has been the subject of many studies in both geological and geophysical fields. This sediment with a calcium carbonate structure exhibited high luminescence properties with X-ray excitation. The radioluminescence (RL) and thermoluminescence (TL) properties were investigated as well as their structural (FT-IR, XRD), morphological (SEM), thermal (TG-DTA) and absorption (UV-Vis-NIR) properties of this sediment. The broad RL peak of septarian was observed at 640 nm. There was a significant increase in the RL intensities of the sifted samples compared with the bulk sample. The TL glow curves of septarian irradiated with X-rays exhibited intense main TL glow peak having the maximum temperatures at 116 °C and about 390 °C with a heating rate of 2 °C/s. Also; the TL kinetic parameters were reported; activation energy (E), frequency factor (s) and the order of kinetics (b) of the first peak have been determined in detail by using peak shape (PS) and Computerized Glow Curve Deconvolution (CGCD) methods. SEM and EDS analysis were performed for the two different layers of septarian. The light colored side with the amorphous structure of the sample has more impurities (such as Fe, Al, Zr, K) than the crystallized and darker side. © 2018 Elsevier B.V.Item Preparation and characterization of novel boron containing nanocomposites with neutron radiation shielding properties(John Wiley and Sons Inc, 2023) Saltan F.; Şirin K.; Aydin S.; Yildirim Y.PVA/PEO/PVP-B4C and PVA/PEO/PVP-BN polymer nanocomposites were prepared using boron nitrite (BN), boron carbide (B4C), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and polyethylene oxide (PEO). B4C and BN nanopowders were added to the mixture at three different percentages: 5%, 10%, and 20%. Thermal characterization was performed by differential scanning calorimetry, differential thermal analysis and thermogravimetry. Scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction were used for surface analysis and crystal structure characterization. The atomic distribution was determined by elemental analysis. Neutron shielding properties were performed at three different gamma peak areas, 1293.56 keV, 1097.33 keV, 416.86 keV, and calculated total macroscopic cross-section ∑T and half-value layer. The ∑T values were found to be in the range of 7.99–14.37 for all synthesized composites. B4C-doped composites show higher protection efficiency against slow thermal neutrons than BN-doped samples. Highlights: Poly(vinyl alcohol)/poly(ethylene oxide)/polyvinylpyrrolidone composites containing boron nanoparticles are flexible and workable. Nanocomposites were prepared with a simple, cheap, and fast method. Prepared boron nanocomposites exhibit slow thermal neutron stopping even at 3 mm thickness. PVA90/PEO5/PVP5-BN and PVA90/PEO5/PVP5-B4C composites are good candidates for demanding military applications such as vehicle and body armor. © 2023 Society of Plastics Engineers.Item Boron containing polyvinyl alcohol/ polyethylene oxide/polyvinyl pyrrolidone composites: Preparation, characterization, gamma radiation shielding and gamma radiation effect on it's thermal properties(Elsevier Ltd, 2024) Saltan F.; Şirin K.; Aydın S.; Taşköprü C.; Yıldırım Y.The production of PVA/PEO/PVP-B4C and PVA/PEO/PVP-BN nanocomposites is presented in this study by adding certain proportions of boron nitride (BN) and boron carbide (B4C) to the polyvinyl alcohol(PVA)/polyethylene Oxide (PEO)/polyvinyl pyrrolidone (PVP) blend. The percentages of BN and B4C nano powder in the PVA/PEO/PVP blend have been determined as 5%, 10% and 20%. Thermal characterizations were carried out with different techniques such as Differential scanning calorimetry (DSC), Differential Thermal Analysis (DTA), Thermogravimetry (TG). Surface, crystal structure and atomic percentage distribution analyzes of the obtained composites were performed by X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction Analysis (XRD), Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX), and elemental analysis. 10 kGy gamma irradiation was performed on PVA/PEO/PVP-B4C and PVA/PEO/PVP-BN composites. The thermal behavior of the composites at this dose level was investigated. In addition, the radiation shielding properties of composite films obtained at 10 cm distances using Am-241 beam source were examined. © 2023 Elsevier Ltd