Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 83 for “"polyether"”.
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Tribological behavior of unfilled and carbon fiber reinforced polyether ether ketone/polyether imide composites
The friction and wear of injection molded Poly(ether ether ketone) (PEEK) and Poly(ether imide) (PEI), PEEK/PEI blends with the weight compositions of 50/50 %, 70/30 %, and 85/15 %, with and without short carbon fibers were measured in a pin(52100 steel ball)-on-disk(polymer blend) configuration …
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Synthesis of a Family of Polyether-Substituted Phenacenes
… be used. A family of [<em>n</em>]phenacenes with polyether solubilizing groups has been synthesized using two separate divergent-convergent synthetic schemes. The central reaction vital to the synthesis is the ultraviolet light induced photocyclization, which allows for elongation of the phenacene …
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Enzymatic Ring Formation in Polyether Tetronate Antibiotic Biosynthesis
… activity of many natural products. The polyether tetronate antibiotics tetronasin, tetronomycin, and tetromadurin (SF2487/A80577) are notable for their ring diversity, each possessing a tetronate, cyclohexane, tetrahydropyran, and at least one tetrahydrofuran ring. The antibiotic …
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Synthesis and characterization of phosphorous containing macromolecular polyether compounds
<p>A radioisotope of rubidium, <sup>82</sup>Rb is used in positron emission tomography. Neutral crown ethers and cryptands have been studied as carrier ligands for Rb<sup>+</sup> but exhibit low ion carrying capacity and high toxicity. The present study involved investigating a lariat ether …
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Biodegradation studies of polyether polyurethane in a landfill site
Polyether polyurethane rigid foams have always been considered as inert materials due to their extreme stability. Urethanes and polyethers, which are the main constituents of the polymer structure, are well known for theirstability and resistance to hydrolysis.t 32 These groups give to the foam its …
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Mechanical response of polyether polyurethane foams under multiaxial stress and the initial yielding of ultrathin films
… we study the mechanical response of elastic polyether polyurethane (EPP) foams by means of experiments, theory, and modeling. The experiments include five loading cases: uniaxial compression along the rise direction; uniaxial compression along two mutually perpendicular transverse directions; …
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The development of iterative and cascade methods for the rapid synthesis of ladder polyether natural products
I. The Development of Methods for the Iterative Synthesis of Polytetrahydropyrans An iterative method comprising chain homologation, epoxidation, 6-endo cyclization, and protiodesilylation was developed. Notable achievements include the development of a novel propargyl organocopper coupling method, …
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Synthesis and characterization of polyether-ester liquid crystalline polyesters and poly(arylene ether ketone)-lcp segmented copolymers
… several novel liquid crystalline aromatic polyether-ester copolymers were synthesized by the incorporation of an A-B monomer, either PAPBA or PANBA, into the polymer main chain. The corresponding copolymers were thermoxidatively stable and melt processable over a wide compositional range. …
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Hyperbranched polymers and Haag type dendrimers for the molecular imprinting of polymers
… both hyperbranched polyglycerol and Haag type polyether dendrons with estradiol as a core. The attachment of the polyether dendron created a dendrimer that had 64 allyl groups available for crosslinking. Completion of the crosslinking of the dendrimer resulted in a polymer that was not fully …
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Design and synthesis of novel hydrogels for biological applications
… project were:1) the synthesis of a range of new polyether-based vinylic monomers and their incorporation into poly(2-hydroxyethyl methacrylate) (poly(HEMA)) based hydrogel networks, of interest to the contact lens industry.2) the synthesis of a range of alkyltartronic acids, and their …
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Characterization of Novel Urethanases and a Commercial Cutinase for the Degradation of Polyurethane
… dicarbamates produced from the glycolysis of polyether-PU foam. Despite the utility of this discovery, the glycolytic pre- treatment prior to carbamate hydrolysis results in undesirable waste byproducts. Thus, in this work, we used sequence similarity networks to mine thermophile genomes in …
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Rhodium-catalyzed epoxide-opening cascades toward brevisin and hemibrevetoxin B
… the synthesis of oxepanes and oxepanecontaining polyethers from di- and trisubstituted epoxides. Syntheses of the ABC and EF ring systems of (-)-brevisin via all endo-diepoxide-opening cascades using this method constitute a formal total synthesis and demonstrate the utility of this methodology …
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Synthesis and Characterization of Novel Polyethers and Polydimethylsiloxanes for Use in Biomaterials
This dissertation focuses on the use of novel polyethers and polydimethylsiloxanes in the stabilization of magnetite nanoparticles as well as biomedical applications. The colloidal stabilities of magnetite nanoparticles coated with polyethers containing various functional endgroups were studied. …
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The extraction of trichlorostannato-rhodium complexes by polyurethane foam
Polyurethane foam (polyether based) has been found to efficiently extract rhodium from hydrochloric acid solutions containing stannous chloride. The amount of rhodium extracted is significantly influenced by inter alia temperature, acid concentration, the Sn(II):Rh mol ratio and the presence of …
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Separation of alkali metal cations and alkaline earth cations using ionizable crown ethers
… of structural variation within the ionizable polyether and environmental variation upon the selectivity and effÃciency in metal ion complexation and transport. Experimental techniques of pK^ determination in dioxane-water systems, solvent extraction, and proton-coupled transport across bulk …
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Siloxane modified polyurea and polyurethane urea segmented copolymers
High molecular weight polyether urea copolymers were synthesized using perfectly difunctional aromatic amine terminated polypropylene oxide (PPO) (2800 <Mn>) prepared via aluminum porphorin initiated coordination polymerization. The resulting segmented copolymer showed much higher tensile strength …
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Synthetic studies towards an organometallic rotaxane
… investigated using our chiral organometallic polyether.
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ΣΥΜΒΟΛΗ ΣΤΗ ΜΕΛΕΤΗ ΤΗΣ ΑΠΟΤΥΠΩΤΙΚΗΣ ΙΚΑΝΟΤΗΤΑΣ ΤΩΝ ΕΛΑΣΤΟΜΕΡΩΝ ΑΠΟΤΥΠΩΤΙΚΩΝ ΥΛΙΚΩΝ
… CONDENSATION AND ADDITION SILICONE AND POLYETHER. THE STUDY OF THE IMPRESSION ABILITY AND ROUGHNESS HAS BEEN MADE WITH THE SCANNING ELECTRONIC MICROSCOPE.
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Interaction of Metal Salts with Polyethers
… models proposed for the structure of salt-polyether complexes. The effect of mercuric chloride on the statistical conformations of poly(propylene-glycol) was studied in a quantitative manner using the relationships of marchal-Benoit. The dielectric relaxation activation energy and mean …
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