Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Author: search.filters.author.Tıhmınlıoğlu, FundaSubject: search.filters.subject.Ion implantation

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  • Master Thesis
    Surface Modification of Chitosan Films/Meshes for Biomaterial Applications
    (Izmir Institute of Technology, 2019) Işıklı, Berçin; Tıhmınlıoğlu, Funda; Tıhmınlıoğlu, Funda; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Modification of surface of biomaterials is a great interest for many years due to first contact of surface of materials with the biological fluids. This thesis aims to investigate surface modification effect on the chemical, surface wettability, protein adsorption as well biodegradability properties of dense chitosan (Ch) and asymmetric chitosan films (ACh). The surfaces of chitosan dense and asymmetric films were modified by ion implantation technique using carbon and carbon-nitrogen hybrid ions at a fluence of 1x1015 ions/cm2 and ion energy of 20kV. Chemical compositions of the film surfaces were analyzed by Fourier transform infrared spectroscopy (FTIR-ATR). Surface hydrophobicity measurements were conducted by static contact angle measurements. Protein adsorption on unmodified and modified surfaces on films was investigated as a function of time at various pH conditions. After ion implantation on chitosan films, both C and C-Nitrogen ion implantation, the surfaces become rougher and hydrophobic having moderate wettability (����� values in the range of 72-85°) and in good agreement with FTIR-ATR data findings. It was found pH dependence of the amount of protein adsorbed on the dense chitosan films as a function of time for both un-implanted and implanted films. BSA and fibrinogen were more adsorbed on the chitosan films at pH 5. The amount of BSA and fibrinogen protein adsorption was 0.97 and 1.33 gprotein/gfilm, respectively for 60 min incubation period. Protein adsorption enhanced for C and C+N2 ion implanted samples for BSA and fibrinogen, respectively due to the hydrophobic protein surface interaction effect. In vitro degradation results showed that ACh films degrade much faster (mass loss 57 %) than Ch films (40 %) due to the porous structure at the end of 3 weeks. However, the ion implanted Ch samples degraded much slower having mass loss of 30% and 17.7% for C+N2 and C implanted samples, respectively at the end of 3 weeks compared to un-implanted Ch films as 40 %. The results are in good agreement with water sorption and surface hydrophobicity of the implanted films. This study demonstrated that surface modification, as well as structure, changes the protein sorption, wettability and biodegradation properties of the chitosan films.
  • Master Thesis
    Characterization of Ultra High Molecular Weight Polyethylene (uhmwpe) Modified by Metal-Gas Hybrid Ion Implantation Technique
    (Izmir Institute of Technology, 2006) Urkaç Sokullu, Şadiye Emel; Tıhmınlıoğlu, Funda; Tıhmınlıoğlu, Funda; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The aim of this work was the characterization of the surface modified Ultra High Molecular Weight Polyethylene (UHMWPE) in order to understand the effect of ion implantation technique on the properties of this material. The samples were Ag and Ag+N hybrid ion implanted by using MEVVA (Metal Vapour Vacuum Arc) ion implantation technique with a fluence of 10 17 ions/cm2, extraction voltage of 30 kV.Untreated and surface treated samples were investigated by Stopping andRange of Ions into Matters (SRIM), Rutherford Back Scattered Analysis (RBS), Attenuated Total Reflection - Fourier Transform Infrared (ATR/FT-IR) Spectroscopy, Raman Spectroscopy, Optical Absorption Photospectroscopy (OAP), Thermo Gravimetry Analysis (TGA), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD) Analysis, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Optical Microscopy (OM), Micro-hardness and Contact Angle Measurement. The results of RBS analysis show that Ag ions were detected up to 32 +15 nm after Ag implantation, and 42 +15 nm after Ag+N implantation., underneath the surface. ATR- FTIR chemical characterization analyses results indicated that the effect of implantation on UHMWPE surfaces caused dehydrogenation of polymer with an increase of C.C bond formation which results in enriching the crosslinking carbon atoms on the surface. Optical Absorption Photospectroscopy and Raman spectrum suggests that the chemical structure of UHMWPE has changed after implantation. The characterization results showed that the ion bombardment induced an increase in the % crystallinity, onset and termination degradation temperatures of UHMWPE obtained by thermal analyses, an increase in hardness, and surface wettability and a decrease in roughness of the polymer. The surface topography results can be attributed to the implantation inducing surface roughness decreasing due to the better wettability properties of surfaces obtained after implantation. In conclusion, this study has shown that ion implantation represents a powerful tool on modifying key properties on UHMWPE surfaces.