WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Conference Object Citation - WoS: 16Thermal Characterization of Ag and Ag Plus N Ion Implanted Ultra-High Molecular Weight Polyethylene (uhmwpe)(Elsevier Ltd., 2007) Urkaç, Emel Sokullu; Oztarhan, A.; Tıhmınlıoğlu, Funda; Kaya, N.; Ila, D.; Muntele, C.; 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 10(17) ion/cm(2) 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. (c) 2007 Elsevier B.V. All rights reserved.Article Citation - WoS: 8Citation - Scopus: 9Polymeric Thermal Analysis of C+h and C+h+ar Ion Implanted Uhmwpe Samples(Elsevier Ltd., 2007) Kaya, N.; Öztarhan, Ahmet M.; Urkaç, Emel Sokullu; Ila, D.; Budak, S.; Oks, E.; Tıhmınlıoğlu, Funda; Muntele, C.Chemical surface characterization of C + H hybrid ion implanted UHMWPE samples were carried out using DSC (differential scanning calorimeter) and TGA (thermal gravimetric analysis) techniques. Samples were implanted with a fluence of 10(17) ion/cm(2) and an extraction voltage of 30 kV. The study of TGA and DSC curves showed that: (1) Polymeric decomposition temperature increased, (2) T-m, Delta C-p and Delta H-m values changed while Delta C-p and Delta H-m increased. T-g value could not be measured, because of some experimental limitations. However, the increase in Delta H-m values showed that T-g values increased, (3) the branch density which indicated the increase in number of cross-link (M-c) decreased in ion implanted samples and (4) increase in Delta H-m values indicated increase in crystallinity of implanted surface of UHMWPE samples.Conference Object The Effect of Ag and Ag Plus N Ion Implantation on Cell Attachment Properties(American Institute of Physics, 2009) Urkaç, Emel Sokullu; Öztarhan, Ahmet; Tıhmınlıoğlu, Funda; Deliloğlu, İsmet Gürhan; İz, Sultan Gülce; Oks, Efim; Ila, DaryushImplanted biomedical prosthetic devices are intended to perform safely, reliably and effectively in the human body thus the materials used for orthopedic devices should have good biocompatibility. Ultra High Molecular Weight Poly Ethylene (UHMWPE) has been commonly used for total hip joint replacement because of its very good properties. In this work, UHMWPE samples were Ag and Ag+N ion implanted by using the Metal-Vapor Vacuum Arc (MEVVA) ion implantation technique. Samples were implanted with a fluency of 1017 ion/cm2 and extraction voltage of 30 kV. Rutherford Backscattering Spectrometry (RBS) was used for surface studies. RBS showed the presence of Ag and N on the surface. Cell attachment properties investigated with model cell lines (L929 mouse fibroblasts) to demonstrate that the effect of Ag and Ag+N ion implantation can favorably influence the surface of UHMWPE for biomedical applications. Scanning electron microscopy (SEM) was used to demonstrate the cell attachment on the surface. Study has shown that Ag+N ion implantation represents more effective cell attachment properties on the UHMWPE surfaces.Conference Object Thermal Behaviour of W Plus C Ion Implanted Ultra High Molecular Weight Polyethylene (uhmwpe)(American Institute of Physics, 2009) Urkaç, Emel Sokullu; Öztarhan, Ahmet; Tıhmınlıoğlu, Funda; Ila, Daryush; Budak, S.; Chhay, B.; Nikolaev, A.The aim of this work was to examine thermal behavior of the surface modified Ultra High Molecular Weight Poly Ethylene (UHMWPE) in order to understand the effect of ion implantation on the properties of this polymer which is widely used especially for biomedical applications. UHMWPE samples were Tungsten and Carbon (W+C) hybrid ion implanted by using Metal Vapour Vacuum Arc (MEVVA) ion implantation technique with a fluence of 10 17 ions/cm2 and extraction voltage of 30kV. Untreated and surface-treated samples were investigated by Rutherford Back Scattering (RBS) Analysis, Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) Spectrometry, Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). This study has shown that ion implantation represents a powerful tool on modifying thermal properties of UHMWPE surfaces. This combination of properties can make implanted UHMWPE a preferred material for biomedical applications.Conference Object Structural and Thermal Characterization of Ti+o Ion Implanted Ultrahigh Molecular Weight Polyethylene (uhmwpe)(American Institute of Physics, 2009) Öztarhan, Ahmet; Urkaç Sokullu, Şadiye Emel; Tıhmınlıoğlu, Funda; Kaya, N.; Ila, Daryush; Budak, S.; Nikolaev, A.In this work, Metal-Gas Hybrid Ion Implantation technique was used as a tool for the surface modification of Ultra High Molecular Weight Polyethylene (UHMWPE). Samples were Ti + O ion implanted by using Metal-Vapour Vacuum Arc (MEVVA) ion implanter to a fluence of 5x10(16) ion/cm(2) for each species and extraction voltage of 30 kV. Untreated and surface treated samples were investigated by Rutherford Back Scattering (RBS) Spectrometry, Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR) Spectroscopy, Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Results indicate that Ti + O ion implantation can be applied on UHMWPE surfaces successfully. ATR-FTIR spectra indicate that the C-H concentration on the surface decreased after Ti + O implantation. Thermal characterization with TGA and DSC shows that polymeric decomposition temperature is shifted after ion implantation.Conference Object Citation - Scopus: 4Trans-resveratrol’ün Kitosan Mikroküreler İçerisindeki Kararlılığı(Institute of Electrical and Electronics Engineers Inc., 2009) Altıok, Duygu; Altıok, Evren; Bayraktar, Oğuz; Tıhmınlıoğlu, Fundatrans-Resveratrol, (3,5,4?-trihydroxy-trans-stilbene), a phenolic compound present in some plant species, have been shown to posses antioxidative, anticarcinogenic and antitumour properties. However, under UV light, it turns into -cis form and looses its bioactivity.This study aims to increase the stability of trans-resveratrol by loading it into chitosan microspheres. Within this context, the trans-resveratrol loaded chitosan microspheres was produced by spray drying and then the resultant microspheres were characterized. The particle size and the surface morphology of resultant microspheres were investigated by scanning electron microscope (SEM) and the thermal properties were determined by thermogravimetry analyser(TGA). The stability of free and that of inside the microspheres was determined by high performance liquid chromatography (HPLC). It was found that the stability of trans-resveratrol incorporated into chitosan microspheres kept constant. ©2009 IEEE.Article Citation - WoS: 5Citation - Scopus: 7Effect of the Zeolite Filler on the Thermal Degradation Kinetics of Polypropylene(Scibulcom Ltd., 2006) Tıhmınlıoğlu, Funda; Pehlivan, Hilal; Balköse, Devrim; Ülkü, SemraIn this study, the thermal degradation behaviour of polypropylene (PP) and polypropylene-zeolite composites was investigated. Clinoptilolite, a natural zeolitic tuff, was used as the filling material into the composites. Effect of both pure clinoptilolite and silver ion exchanged form of clinoptilolite addition on the thermal degradation kinetics of polypropylene composites was studied by using differential scanning calorimetry (DSC) and thermal gravimetry analysis (TGA) techniques. Polymer degradation was evaluated by using DSC with heating rates of 5, 10, and 20 degrees C/ min from room temperature up to 500 degrees C. Silver concentration (4.36, 27.85 and 183.8 mg Ag/g zeolite) was the selected parameter under consideration. From the DSC curves, it was observed that the heat of degradation values of the composites containing 2-6% silver exchanged zeolites (321-390 kJ/kg) were larger compared to that of the pure PP free of silver and zeolite (258 kJ/kg). From the DSC results it was confirmed that PP-zeolite composites can be used at higher temperatures compared to the pure PP polymer because of its higher thermal stability. The thermal decomposition activation energies of the composites were calculated by using both the Kissenger and Ozawa models. The values predicted from these two equations were in close agreement. From the TGA curves, it was found that zeolite addition into the PP matrix speeds down the decomposition reaction, however, silver exchanged zeolite addition into the matrix accelerates the reaction. The higher the silver concentration, the lower the thermal decomposition activation energies were obtained. As a result, PP was found to be much more susceptible to thermal decomposition in the presence of silver exchanged zeolite.Article Citation - WoS: 2Citation - Scopus: 10Water and Water Vapor Sorption Studies in Poly(propylene)-Zeolite Composites(John Wiley and Sons Inc., 2003) Pehlivan, Hilal; Özmıhçı, Filiz; Tıhmınlıoğlu, Funda; Balköse, Devrim; Ülkü, SemraWater and water vapor sorption to porous poly(propylene)zeolite composites prepared by hot pressing have been studied as a function of zeolite loading. This work presents the first report on the effect of the zeolite as a filler on the water sorption properties of PP composites. Water swelling experiments were conducted at 25°C using pure PP and PP-zeolite film samples having different zeolite loadings (6-40 wt%). Since PP is a hydrophobic polymer, it does not sorp any water, but the composites having 10, 20, 30, and 40% zeolite sorbed 0.63, 1.00, 1.72 and 3.74 wt% water, respectively. The zeolite itself at the same conditions sorbed 24.5 wt% water. As the filler loading in the composites increased, equilibrium uptake values increased too. On the other hand, water vapor sorption and kinetics has been studied using a Cahn 2000 gravimetric sorption system. Within in the range 0.35-0.95%, water vapor was adsorbed by the composites containing 10-40 wt% zeolite. Experimental effective water vapor diffusivities of the composite films were about one order of magnitude higher than the experimental water diffusion coefficient in composites. The transport of water in composites was slower than that in the liquid water due to the longer diffusion pathway and adsorption on the surface of the composites. Although the liquid water may fill all the voids in the composite, water vapor is adsorbed on the surface of the zeolite only.Article Citation - WoS: 8Citation - Scopus: 8Phase Equilibrium and Diffusion of Solvents in Polybutadiene: a Capillary-Column Inverse Gas Chromatography Study(John Wiley and Sons Inc., 2002) Cai, W. D.; Ramesh, N.; Tıhmınlıoğlu, Funda; Danner, Ronald P.; Duda, John Larry; De Haan, A.The capillary-column inverse gas chromatography method was used to measure the diffusion and partition coefficients of ethylbenzene, styrene, and acrylonitrile in polybutadiene (PBD) at infinite dilution of the solvents. Experiments were performed over a temperature range of 50-125°C. At temperatures well above the glass-transition temperature of PBD, the diffusivities were correlated using an Arrhenius expression. The Arrhenius parameters in turn were intercorrelated and shown to be a function of the occupied volume, thus providing a method for predicting the diffusion of other solvents in the same polymer. Further, the activation energy was predicted using the Duda-Vrentas free-volume approach. The activation energy thus obtained was compared with the activation energy of the Arrhenius approach. The weight-fraction activity coefficient data were compared to the predictions of the group contribution, lattice-fluid equation-of-state, and the UNIquac Functional-group Activity Coefficient (UNIFAC) free-volume models.Article Citation - WoS: 11Citation - Scopus: 13Sorption and Diffusion of Water Vapour on Edible Films(Springer Verlag, 2008) Berkün, Didem; Balköse, Devrim; Tıhmınlıoğlu, Funda; Alsoy Altınkaya, SacideTwo types of films consisting of sodium salt of carboxymethyl cellulose (NaCMC) and hydroxypropyl cellulose (HPC) as film forming materials and glycerin as plasticizer were prepared, characterized and their water vapour sorption properties were determined. The water sorption isotherms of the films were measured using a magnetic suspension balance. Results show that diffusion of water vapour in NaCMC based film is faster than that in HPC based films, due to the heterogeneous structure and larger pore dimensions of the NaCMC films.
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