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Polymerization And Characterization Of Allyl MethacrylateVardareli, Tugba 01 September 2006 (has links) (PDF)
Allyl methacrylate, AMA was polymerized by chemical initiator and by & / #947 / -radiation under different conditions. The polymer obtained is mostly gel type with some soluble fractions at lower conversions. Arrhenius activation energy is 82.3 kJ/mol for chemical initiated polymerization. The polymer was characterized by FT-IR, NMR, DSC, TGA, XPS, XRD, DLS, and MS methods. It was found that about 98-99% of allyl side groups retained as pendant even after completion of the polymerization, while 1-2% may give crosslinking and/or cyclization that yields lactones and anhydrides. The spectroscopic and thermal results of the work showed that the reaction is not cyclopolymerization, but may have end group cyclization. Molecular weight of 1.1x106 was measured by DLS. Therefore, insolubility is due to the high molecular weight of polymer, even in the early stage of polymerization rather than crosslinking. The Tg of PAMA was observed as 94º / C before curing, upon curing at 150-200º / C, Tg increased to 211º / C as measured by DSC. The thermal treatment of polymer at about 350º / C gave anhydride by linkage type degradation, following side group cyclization. The XPS analysis showed the presence of radical fragments of AIBN and CCl4 associated with oligomers. The MS and TGA thermograms showed two or three stage degradations depending on solubility. The first stage was mostly linkage type degradation for the fragmentation of pendant allyl groups at 225-350º / C. In the second stage, at 395-515º / C, the degradation is random scission and depolymerization.
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Graft Copolymerization Of P-acryloyloxybenzoic Acid Onto High Density PolyethyleneCagirici, Seda 01 December 2003 (has links) (PDF)
The monomer, p-acryloyloxybenzoic acid (ABA) was synthesized by condensation reaction of acryloyl chloride and p-hydroxybenzoic acid in alkaline medium. Polymerization of the monomer and grafting of the produced
polymer (PABA) onto high density polyethylene (HDPE) were expected to be carried simultaneously in melt mixing at high temperature. The graft copolymerization was studied at varying concentrations of the monomer in the reaction mixture at constant temperature (200 0C).
Grafted HDPE samples were investigated by several techniques such as DSC, FTIR, MFI and mechanical testing.
The tensile tests of PABA-g-HDPE showed an improvement particularly in stress at yield and Young&rsquo / s modulus whereas the strain at break values showed a decrease for all compositions compared to neat HDPE.
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Accelerated Aging Of Elastomers In Aqueous MediaInaler, Ekrem 01 January 2007 (has links) (PDF)
EPDM (Ethylene-Propylene-Diene Monomer)/PP (Polypropylene) based TPV (Thermoplastic Vulcanizate) was aged in a closed system at stabilized temperature and pressure at 80, 100 and 120oC in distilled water, detergent solution and shiner solution.
The variation in properties of TPV upon aging were followed by using DSC (Differential Scanning Calorimetry), TGA (Thermogravimetric Analysis), tensile testing, Shore A rubber hardness testing.
DSC analysis indicated that percent crystallinity of PP component in TPV increased at 100oC whereas crystal structure was deformed at 120oC. In addition to this, hardness test showed that the hardness of TPV remained almost constant in distilled water aging except 120oC water aging but TPV became softer in detergent and shiner solution upon all aging temperatures used in this study. Tensile testing confirmed the hardness analysis that the loss in mechanical properties of TPV was observed except 100oC water aging. TGA analysis showed that percent crystallinity increase causes enhancement in degradation temperature of EPDM/PP blend in air.
It is detected that TPV is quite resistant to 80oC aging, but TPV loses its resistance to preserve its characteristics at 120oC aging. It is also determined that aging media is as important as temperature to evaluate the performance of TPV. Moreover, it is decided that the rate of aging directly proportional to detrimental rate is arranged in an order from the slowest to the fastest as distilled water, detergent and shiner solution media.
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Structural Analysis Of Polyaniline-polypyrrole Copolymers Via Pyrolysis Mass SpectrometryTezal, Feride 01 February 2007 (has links) (PDF)
This thesis describes recent progress in electrochemical preparation of several
conducting polymers. In particular, the synthesis and characterizations of pure
polyaniline, pure polypyrrole, polyaniline/polypyrrole and polypyrrole/polyaniline
copolymers and polyaniline-polypyrrole physical blends were studied. The focus
has included firstly synthesis of these electrically conductive polymers.
Secondly, thermal characteristics of electrochemically synthesized homopoly- mers,
copolymers and their physical blends were investigated by thermal gravi- metric
analysis (TGA), differential scanning calorimetry (DSC) and direct pyrol- ysis mass
spectrometry (DIP-MS) techniques. In general, TGA analysis showed three-step
thermal degradation. The first, at 100oC, was attributed to water, and unreacted
monomers. The second weight losses observed at around 150 oC was because of
evolution of water and/or acid. Finally, the removal of the dopant ion and low
molecular weight species from the matrix were observed for pure PANI and pure PPy
at 230 and 280 oC, respectively. PANI/PPy films and PPy/PANI films have
decomposition temperatures at 272oC because of the loss of the dopant ion. It was also observed that pure PPy was thermally more resistant than pure PANI.
Thirdly, thermal characteristics, and degradation products of electrochemi- cally
prepared PANI/PPy and PPy/PANI films in solutions containing variable dopant
(SO42& / #8722 / ) concentrations were analyzed and compared with pyrolysis mass spectrometry.
Similar to TGA study, there were three main thermal degradation steps namely,
evolution of low molecular weight species, dopant based products and degradation
products of polymers. The dopant concentration was monitored
to optimize the degradation behavior. Pyrolysis mass spectrometry data showed that the degree of degradation of the polymer already coated on the electrode
enhanced as the dopant concentration used in synthesis increased.
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Microwave-assisted Simultaneous Novel Synthesis Of Poly(dibromophenylene Oxide)s, Poly(diiodophenylene Oxide)s (p), Conducting(cp) And/or Crosslinked (clp) And/or Radical Ion Polymers (rip)Celik, Guler (bayrakli) 01 March 2007 (has links) (PDF)
Microwave-assisted novel synthesis of poly(dibromophenylene oxide) or poly(diiodophenylene oxide) (P), conducting polymer (CP) and/or crosslinked polymer (CLP) and/or radical ion polymer (RIP) were achieved simultaneously from lithium, sodium or potassium 2,4,6-bromophenolate or sodium 2,4,6-iodophenolate in a very short time interval.
Polymerizations were carried out by constant microwave energy with different time intervals varying from 1 to 20 min / or at constant time intervals with variation of microwave energy from 70 to 900 watt / or varying the water content from 0.5 to 5 ml at constant time intervals and microwave energy. Poly(dihalophenylene oxide) and radical ion polymers were characterized by FTIR (Fourier Transform Infrared), 1H-NMR (Proton Nuclear Magnetic Resonance), 13C-NMR (Carbon-13 Nuclear Magnetic Resonance), TGA/ FTIR (Thermal Gravimetric Analysis / Fourier Transform Infrared), DSC (Differential Scanning Calorimeter), SEM (Scanning Electron Microscope), ESR (Electron Spin Resonance), GPC (Gel Permeation Chromatography), UV-Vis (UV-Visible Spectroscopy), Light Scattering and Elemental Analysis. Conducting and crosslinked polymers were characterized by FTIR, TGA/ FTIR, DSC, SEM, ESR, XRD (Powder Diffraction X-Ray) and Elemental Analysis.
The effects of heating time, microwave energy and water content on the percent conversion and the polymer synthesis were also investigated.
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Synthesis, Characterization, And Polymerization Of Polyether Bridged Thiophene And Aniline DerivativesTirkes, Seha 01 February 2008 (has links) (PDF)
New compounds consisting of 3-thienyl and aniline units linked by polyether bridges have been synthesized and their electrochemical polymerization was performed via constant potential electrolysis and cyclic voltammetry. In the case of 3-thienyl derivatives two compounds, 1,12-di-3-thienyl-2,5,8,11-tetraoxadodecane (MI) and 1,15-di-3-thienyl-2,5,8,11,14-pentaoxapentadecane (MII) were synthesized utilizing literature methods and their corresponding polymers, poly(I) and poly(II) were prepared in an electrolytic solution containing 0.1 M terabutylammonium hexafluorophosphate (TBAPF6) dissolved in CH3CN. On the other hand, polymerization of aniline derivatives, 2,2' / -[ethane-1,2-diylbis(oxyethane-2,1-diyloxy)]dianiline (MIII) and 2,2' / -[oxybis(ethane-2,1-diyloxyethane-2,1-diyloxy)]dianiline (MIV), was achieved in an aqueous solution containing 3.0 mol.L-1 H2SO4. Spectroelectrochemical (SPEL) properties and thermal analysis of the resulting polymers have been investigated using UV-vis, and Thermogravimetric Analysis (TGA). MIII was also polymerized via chemical oxidation for comparison purposes. The polymers were characterized using 1H-NMR and FT-IR spectroscopic techniques. Furthermore, copolymers of MIII and MIV with aniline (ANI) were also studied with cyclic voltammetry (CV). SPEL behavior and electrical conduction mechanism of resulting copolymers were investigated using UV-vis spectroscopic technique and four-point probe technique, respectively.
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Sulfonated Styrene-co-maleic Acid And Its Derivatives As Superplasticizers In ConcreteYeniay, Secil 01 April 2008 (has links) (PDF)
In the past three decades, a new group of concrete admixtures, termed &ldquo / superplasticizers&rdquo / , were introduced to the concrete industry. They have gained wide acceptance because of their many advantages. The addition of superplasticizers to concrete improves the workability and strength of concrete. In this study, the effect of the chemical structure of poly (4-styrenesulfonic acid-co-maleic acid) sodium salt (SSAMA), which contains both sulfonic and carboxylic acid groups, which is a new superplasticizer, was analyzed. Two different molecular weights of PEG (polyethylene glycol monomethyl ether) were grafted to this water-soluble copolymer at different weight compositions. The structures of synthesized copolymers were verified by FTIR and NMR analyses. The molecular weight difference of the grafted copolymers with different side chain lengths was determined by dilute solution viscosimetry. The effects of chemical structure of grafted copolymers on the fluidity of cement paste and the mechanical properties of the mortars were investigated. The zeta potential measurements revealed the interactions between the cement particles and polycarboxylate type superplasticizers.
The maximum fluidity was achieved for the PEG grafted copolymer with the weight ratio 3:3. The mechanical properties of this copolymer showed the highest flexural and compressive strength compared to other copolymers.
The addition of various Li salts to SSAMA affected the ionic medium, therefore, the dispersion performance of cement paste and the mechanical properties of the mortars improved. The mixture of LiCl: SSAMA in 1:1 mol ratio exhibited the maximum fluidity compared to other Li salts and their compositions. This mixture gave the highest flexural strength but the mixture of Li2CO3 in 1:1 composition gave the highest compressive strength in each salt mixtures.
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Investigation Of Thermal Characteristics Of Naphthoxazines And Polynaphthoxazines Via Pyrolysis Mass SpectrometryKoyuncu, Zeynep 01 May 2009 (has links) (PDF)
In this study, polymerization mechanisms of aromatic (C6H5 or C6F5) and alkyl (CH3, C2H5, C3H7, C6H13, C12H25 or C18H37) amine based naphthoxazine monomers (15-Na, 15Na-C1, 15Na-C2, 15Na-C3, 15Na-C6, 15Na-C12 and 15Na-C18) and thermal degradation mechanisms of polynaphthoxazines synthesized by curing the naphthoxazine monomers (P-15-Na, P-15NaF, P-15Na-C1, P-15Na-C2, P-15Na-C3, P-15Na-C6, P-15Na-C12 and P-15Na-C18) were studied by direct pyrolysis mass spectrometry.
During the curing process, the evolutions of monomer and low mass aromatic or alkyl amines were detected below the curing temperature. The mass spectrometry findings indicated that the monomers were subjected to evaporation and degradation to a certain extent but also to polymerization during the curing process.
It has been determined that the polymerization of aromatic amine based naphthoxazine monomer proceeded through the aniline units, either by coupling of the radicals produced by the ring opening of the side chains or by substitution to the benzene ring of aniline. However, even if no direct evidence to confirm polymerization by attack of &ndash / NCH2 groups to naphthalene ring was detected, it is not possible totally eliminate its existence.
The evolution of aniline, the main thermal degradation product for this polymer was observed at relatively low temperatures indicating that thermal decomposition started by elimination of aromatic amine involving linkages. Coupling of &ndash / CH2 groups generated by loss of aniline, yielded naphthoxazines with unsaturated linkages that can recombine and form a crosslinked structure with higher thermal stability.
Similarly, the polymerization of naphthoxazines based on alkyl amines followed opposing paths. The mass spectral data indicated that the coupling of alkyl amine radicals was the main polymerization pathway.
Again, thermal decomposition of alkyl amine based naphthoxazines was started by loss of alkyl amines and diamines. The crosslinked structures produced by coupling of the radicals generated by lose of alkyl amines decomposed at relatively high temperatures.
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Vancomycin Containing Plla Delivery System For Bone Tissue Biocompatibility And Treatment Of Implant Related Chronic OsteomyelitisUysal, Berna 01 September 2009 (has links) (PDF)
Osteomyelitis is an infection of bone or bone marrow, usually caused by pyogenic bacteria. It can cultivate by hematogen way or it can cultivate by the help of local soft tissue infection. Osteomyelitis often requires prolonged antibiotic therapy and surgery. But for therapy / antibiotic must reach to effective dose in the bone. So that / for prevention and treatment of osteomyelitis controlled antibiotic release systems can be used. These systems have been developed to deliver antibiotics directly to infected tissue. As a carrier material / polymers are widely use. Polymer can be biodegradable or non biodegradable. The advantage of biodegradable polymers is / you do not need a second surgery for the removal of the carrier material from the body.
In this study / vancomycin loaded PLLA/TCP composites were developed and characterized to treat implant related chronic osteomyelitis in experimental rat osteomyelitis model. Some of the composites were prepared by coating the vancomycin loaded composites with PLLA to observe the difference between the coated and uncoated composites. Also, some composites were developed free from the vancomycin to determine the biocompatibility of the composite for the bone tissue. The coating extended the release of the vancomycin up to 5 weeks and changed the surface morphology of the composites. According to the cell culture studies, vancomycin loaded PLLA/TCP composites promoted cell adhesion, cell proliferation and mineralization so / the composite was biocompatible with bone tissue. Radiological and microbiological evaluations showed that vancomycin loaded and coated vancomycin loaded PLLA/TCP composites inhibited MRSA proliferation and treat implant related chronic osteomyelitis.
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Synthesis Of Acrylic Based High Internal Phase Emulsion Polymers And Their Application In ChromatographyTunc, Yeliz 01 September 2009 (has links) (PDF)
High internal phase emulsion polymers (PolyHIPEs) are new generation materials with their high porosity and interconnected open-cell structures and finds applications in areas such as supports for catalytic systems, separation media and tissue engineering scaffolds. Styrene based PolyHIPEs are currently the most popular choice, but solvent compatibility and poor mechanical properties of these materials prevent their applications. Therefore development of new polyHIPEs with desired mechanical and cellular properties is needed to extend the range of applications.
The objective of this thesis was to synthesize new polyHIPEs with different mechanical characteristics changing from ductile to elastomeric. For this purpose, acrylic based polyHIPEs with various cellular structure and mechanical characteristics were developed by using stearyl acrylate (SA), isodecyl acrylate (IDA), isobornyl methacrylate (IBMA) and divinylbenzene (DVB). All materials were highly porous (90%) and had open cellular structure with uniform voids in the range of 5.2-12.9 & / #956 / m. The PolyHIPEs
produced from the monomers of SA and IDA demonstrated elastomeric property and had high ability of recovery when the applied stress is removed. IBMA based polyHIPEs were ductile and demonstrated higher Young&rsquo / s modulus and compression strength than that of conventional styrene based polyHIPEs. Therefore, by varying the composition, it became possible to alter the mechanical properties of polyHIPEs from ductile to elastomeric, without changing the interconnected cellular structures.
One of the prepared IDA based polyHIPE was evaluated as stationary phase for capillary electrochromatography for the first time in literature. The column was very efficient in the separation of alkylbenzenes namely thiourea, benzene, toluene, ethylbenzene, propylbenzene and butylbenzene with high column efficiency (up to 200.000 plates/m).
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