Master Degree / Yüksek Lisans Tezleri

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Department: search.filters.department.Thesis (Master)--İzmir Institute of Technology, Chemical EngineeringSubject: search.filters.subject.Polymers

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Now showing 1 - 7 of 7
  • Master Thesis
    Investigation of Different Uv Stabilizer Effects on Hdpe Grades
    (Izmir Institute of Technology, 2019) Germen, Oktay; Şeker, Erol; Şeker, Erol; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    In this study, a performance Hindered Amin Light Stabilizer (HALS), used to prevent the structure of polymeric materials from UV and thermal degradation, was investigated using High Density Polyethylene (HDPE) injection grade. The primary goal of this study is to understand the effects of different HALS types, that consist of low molecular mass and high molecular mass, on mechanical and physical properties of HDPE using a design of experiment method. In addition, Minitab program was used to analyze the data, obtained with the experimental design, with ANOVA analyses to estimate the OIT and Loss Elongation% responses of the samples made with varying HALS amounts and types. Briefly, Elongation Lost% which is the ratio of Elongation% Before Aging to Elongation % After Aging and OIT(Oxidative Induction Time) were studied in different recipes of HDPE Injection Molding Plaque specimens in order to measure the effect of HALS1 (Tin770), HALS2(Tin622) and HALS3(Chim944) on aging. One-year of aging was simulated using a standard aging chamber. It was observed that synergetic effect of HALS1 with HALS3 was much more effective than thatof HALS2 with HALS3. Moreover, it was determined that the samples containing antioxidant which did not contain any HALS additive were completely degraded at the end of the same aging process. This study showed that OIT results of samples were affected directly by the amount of HALS3 which protected the polymer against long-term exposure to UV radiation and high temperature whereas neither HALS1 nor HALS2 showed the same protection.
  • Master Thesis
    Development of Arginine-Containing Well-Defined Polymers
    (Izmir Institute of Technology, 2014) Taykoz, Damla; Bulmuş Zareie, Volga; Bulmuş Zareie, Esma Volga; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The aim of this work is to synthesize arginine-containing well-defined polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization and perform preliminary investigation on the use of these polymers in nucleic acid complexation for potential gene therapy applications. Pentafluorophenyl methacrylate (PFMA) was chosen as an active ester monomer to produce polymers having functional groups available for further modification. RAFT polymerization of PFMA was performed varying polymerization conditions such as feed composition and polymerization temperature. Polymers (PPFMA) were characterized using nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography. Linear increase in ln[M]0/[M] with polymerization time, and number average molecular weight (Mn) with monomer conversion indicated RAFT controlled polymerization of PFMA under the conditions tested. Furthermore, block copolymers of PFMA with poly(ethylene glycol) methacrylate (PEGMA) as a biocompatible component were prepared. Copolymerization was studied using both P(PFMA) and P(PEGMA) as macro RAFT agent. Copolymerization kinetic studies indicated that chain extension block copolymerizations were successfully performed using both macroRAFT agents. P(PFMA) was reacted with arginine methylester (AME) in the presence of triethylamine (TEA). 100% of P(PFMA) active ester groups could be modified with AME at a polymer/AME/TEA mole ratio of 1/1/3, as determined by 1H-NMR spectroscopy. The AME modified polymers were complexed with a 681-bp DNA fragment through electrostatic interactions at varying nitrogen/phosphate (N/P) ratios. Gel electrophoresis experiments revealed that AME-modified P(PFMA) was able to complex with DNA at a N/P ratio of 200. Furthermore, the hydrodynamic diameter (Dh) of polymer/DNA complexes in phosphate buffer saline was found to be 58 nm, while the free DNA displayed a Dh of 109 nm, indicating the complexation of DNA by AME-modified P(PFMA).
  • Master Thesis
    Measurement and Modeling of Thermodynamic and Kinetic Data of Membrane Forming Systems
    (Izmir Institute of Technology, 2007) Arslan, Mine Özge; Alsoy Altınkaya, Sacide; Alsoy Altınkaya, Sacide; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Phase inversion process involving a ternary system (nonsolvent/solvent/ polymer) isfrequently used to prepare porous and asymmetric polymeric membranes. The thermodynamic and kinetic data for the ternary system are required to understand membrane formation mechanisms, change the preparation conditions and predict the final structure of the membranes. In this study, cloud point curves for polysulfone (PSf)/1-methyl-2-pyrrolidinone (NMP)/water, PSf/tetrahydrofurane (THF)/water, PSf/NMP/ethanol, PSf/THF/ethanol, polymethyl methacrylate (PMMA)/acetone/water, PMMA/ THF/water, PMMA/acetone/formamide and PMMA/THF/formamide systems were measured by titrating polymer solutions with nonsolvents until the onset of turbidity.Binodal curves were calculated by using the Flory Huggins theory with constant interactionparameters. Theoretical ternary phase diagrams were found to be in good agreement with experimental cloud point data. In addition to liquid liquid equilibrium data, sorptionisotherms and diffusion coefficients of water, ethanol and chloroform were measured byusing a magnetic suspension balance. Results of kinetic studies have shown that water sorption in PSf films exhibits Fickian diffusion while anomalous diffusion is observed for ethanol and chloroform sorption. The kinetic data for water sorption was analyzed using a simple Fickian diffusion model to determine the diffusion coefficients. On the other hand, anamalous sorption kinetics were interpreted by a mathematical model involving independent contributions from Fickian diffusion and polymer relaxations. The model successfully fits non-Fickian anomalies including sorption overshoot and allows to determine diffusion coefficients and relaxation times. Diffusivities of penetrants in PSf was found to decrease in the following order: Water > Chloroform > Ethanol. Equilibrium sorption isotherms of ethanol and chloroform are well described by classical Flory Huggins thermodynamic theory with constant interaction parameters. A modified version of this theory for concentration dependent interaction parameter is used to correlate the sorption isotherm of water. Vrentas Duda free volume theory is able to correlate diffusivity data of water collected at 30 C and 40 C while the theory fails to correlate the diffusivities of ethanol and chloroform both of which were determined from diffusion-relaxation model.
  • Master Thesis
    Preparation and Characterization of Antimicrobial Polymeric Films for Food Packaging Applications
    (Izmir Institute of Technology, 2007) Gemili, Seyhun; Alsoy Altınkaya, Sacide; Alsoy Altınkaya, Sacide; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    In this study, cellulose acetate (CA) based antimicrobial packaging materials containing lysozyme as an antimicrobial additive were developed. In order to achieve appropriate controlled release of antimicrobial agent, the structure of the films were changed from highly asymmetric and porous to dense ones by modulating the composition of the initial casting solution. The effectiveness of the films were then tested through measurement of soluble and immobilized lysozyme activity, release kinetics and antimicrobial activity on selected microorganisms. The highest release rate, soluble lysozyme activity and resulting antimicrobial activity (on E.coli) was obtained with the film prepared from 5 % CA solution including 1.5 % lysozyme. Increasing CA content in the casting solution decreased the porosity of the films, hence, reduced the release rate, maximum released activities and the antimicrobial activities of the films. On the other hand, immobilized activities and the tensile strength of the films increased. The mechanical properties of the antimicrobial films cast with 5 % and 10 % CA were similar to those of lysozyme free CA films. However, significant reductions in tensile strength and elongation values were observed for the antimicrobial films prepared with 15 % CA. Differences in the release rates, soluble, immobilized and antimicrobial activities at porous and dense surfaces of the films suggest that different surfaces of CA films can be employed for antimicrobial packaging according to the targeted shelf-life of the food products. When the films made with 5 % CA were stored at 4 °C for a maximal period of 105 days, an increase in soluble lysozyme and antimicrobial activities of the films were observed. The results demonstrate that CA films prepared in this study show promising potential to achieve controlled release in antimicrobial packaging.
  • Master Thesis
    Synthesis of Amine Containing Well-Defined Polymers Via Reversible Addition-Fragmentation Chain Transfer (raft) Polymerization and Their Characterization
    (Izmir Institute of Technology, 2013) Kurtuluş, Işıl; Bulmuş Zareie, Volga; Bulmuş Zareie, Esma Volga; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The aim of the study is to synthesize well-defined, spermine-like, amine containing polymers via reversible addition fragmentation chain transfer (RAFT) polymerization as a potential endosomal escaping agent for intracellular drug delivery applications. Tert-butyl (2-((tert-butoxycarbonyl) amino) ethyl)(2-hydroxyethyl)carbamate was first synthesized and then methacrylated to yield 2-((tert-butoxycarbonyl) (2- ((tert-butoxycarbonyl) amino) ethyl) amino) ethyl methacrylate, (BocAEAEMA). BocAEAEMA was then polymerized via RAFT polymerization. A series of RAFT polymerization kinetics experiments were performed in order to investigate the RAFTcontrolled character of polymerizations. The effect of [M]/[R] ratio at constant monomer (0.36 M, 0.72 M and 1.44 M) and initiator concentrations (3.6x10-3 M) on polymerization kinetics was first investigated. Linear proportionality between ln [M]0/[M] and polymerization time, and Mn and conversion, indicated the RAFTcontrolled polymerization of BocAEAEMA monomer under the conditions tested. Boc-AEAEMA polymers were deprotected to yield AEAEMA polymers prior to assays performed to determine cytotoxicity and proton sponge capacity of polymers. Proton sponge capacity of AEAEMA polymers (5.5 kDa and 8 kDa) and PEI (25 kDa and 60 kDa) was investigated via potentiometric titration using constant polymer (2.2 x10-5 M) or repeating unit (2.9 x10-5 M) concentrations. The proton sponge capacity of p(AEAEMA)was found to be comparable to those of PEIs at the same repeating unit concentration. AEAEMA polymers did not show cytotoxic effect on NIH 3T3 cells up to 1.6 M concentration, tested via a cell viability assay for 24h and 72 h.
  • Master Thesis
    Development of End-Group Functional Temperature-Responsive Polymers
    (Izmir Institute of Technology, 2013) Özer, Ekrem; Bulmuş Zareie, Volga; Bulmuş Zareie, Esma Volga; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The aim of this thesis was to synthesize temperature-responsive, well-defined, end-group modified (co)polymers of oligoethyleneglycol methyl ether methacrylate (OEGMA300) and diethyleneglycol methyl ether methacrylate (MEO2MA) via reversible addition fragmentation chain transfer (RAFT) polymerization, and to investigate in detail the temperature-responsive behaviour of the resultant (co)polymers considering the possible use of these (co)polymers in temperature-controlled biosensing applications. A series of (co)polymerization kinetic experiments were performed at three different [Total monomer]/[RAFT agent] molar ratios and yielded copolymers of OEGMA300 and MEO2MA with controlled molecular weights and low polydispersities (<1.2), indicating RAFT-controlled (co)polymerization mechanism. The reactivity ratios of the comonomers, MEO2MA and OEGMA300, determined using Kelen-Tüdŏs method were 0.96 and 0.98, respectively. This indicated that the copolymers were truly random and their composition could be controlled by the feed comonomer composition. A number of (co)polymers having varying molecular weights, compositions and end-group functionalities (i.e. thiocarbonylthio RAFT end-group, pyridyldisulfide (PDS) or phosphonate group) were synthesized to investigate the effects of these parameters on the Lower Critical Solution Temperature (LCST) of the (co)polymers. The end-group functionality, PDS or phosphonate, was chosen considering the possible use of these polymers on gold or alumina surfaces, respectively. The key factor affecting the LCST was found to be the hydrophilic/hydrophobic balance of the (co)polymers. Increasing the hydrophilic content (OEGMA content) of the (co)polymers increased the LCST values. The effect of end-group on the LCST was more profound for (co)polymers with low molecular weights. Replacement of the thiocarbonylthio end-group with a more hydrophilic group such as PDS or phosphonate resulted in a significant increase in the LCST of the copolymers having a degree of polymerization of less than 30. For the copolymers with higher degree of polymerization, the influence of the end-group chemistry on the LCST became negligible.
  • Master Thesis
    Fabrication of Transparent Polymer Nanocomposites Containing Pmma-Grafted Ceo2 Particles
    (Izmir Institute of Technology, 2011) Parlak, Onur; Demir, Mustafa Muammer; Demir, Mustafa Muammer; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The composite materials prepared by transparent polymer and nanosized particles possess promising future in optical design and applications since their controllable optical properties. In this study, transparent/translucent composite films based on polystyrene (PS) and poly(methyl methacrylate) (PMMA)-grafted CeO2 nanoparticles were prepared. CeO2 nanoparticles were precipitated from Ce(NO3)3·6H2O and urea in dimethyl formamide at 120°C. The surface of the nanoparticles was modified with a polymerizable surfactant, 3-methacyloxypropyltrimethoxy silane (MPS) in situ at 0°C. The size of the particles was fixed to 18 nm in diameter. The particles were dispersed into a mixture of MMA:toluene solution. The free radical solution polymerization was carried out in situ at 60°C using benzoyl peroxide (BPO) as initiator. A PMMA layer is formed around CeO2 nanoparticles. The thickness of the shell ranged from 9 to 84 nm was controlled by the amount of BPO using 6 and 0.5 wt %, respectively with respect to monomer. The layer thickness was found to be inversely proportional with the amount of initiator. The resulting PMMA-grafted CeO2 particles were blended with PS in tetrahydrofuran and the solution was spin-coat on a glass slide. CeO2 content in the composite films was fixed to 5.5 wt %. The transmission of the films was examined by UV-vis spectroscopy. The transmission of the PS composite prepared by neat CeO2 particles was 71 %. It was increased to 85 % when the composite prepared with PMMA-grafted CeO2 particles whose PMMA thickness is 9 nm. We believe that the achievement in transparency is most probably due to the reduction in refractive index mismatch between CeO2 particles and PS matrix using PMMA layer at interface.