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 210 for “"Transition Temperatures"”.
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The Structural Bases for Polymer Glass-Transition Temperatures.
North Carolina State University Theses Textile Engineering, Chemistry and Science.
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Superconducting transition temperatures of amorphous bismuth alloy films
Measurements have been made of the critical temperatures T of c amorphous bismuth alloy films containing lead, thallium, and antimony in concentrations up to 13 atomic percent. The results indicate that the shift in T is approximately linear in impurity concentration, as c expected. The derivative …
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Chemical and physical stability of spray-dried and glass encapsulated spray-dried flavors stored below their glass transition temperatures
… chemical and physical stability at all storage temperatures (Ts) and times, 3) determine possible mechanisms of flavor loss, such as volatile permeation and/or oxidative degradation, and 4) provide recommendations for shelf-life extension of MET flavors. One benzaldehyde SD flavor and two MET …
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Twofold switchable block copolymers based on new polyzwitterions
… in water, exhibiting upper critical solution temperatures (UCST). Phase transition temperatures depend notably on the molar mass and polymer concentration, and are much higher in D2O than in H2O. Also, the phase transition temperatures are effectively modulated by the addition of salts. The …
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Synthesis and characterisation of Acylhydrazinatometallomesogens
… to mesophase and mesophase to isotropic phase transition temperatures whilst ascending a homologous series. The N-alkylideneacylhydrazinato metallomesogens were synthesised and later characterised spectroscopically. The effects of structural change on mesophase character was deternthed by …
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The investigation of some novel polysiloxane liquid crystal systems.
… The effect of system purity on the phase transitions of the ring materials was found to be crucial, and this has resulted in a phase diagram for a 'doped' ring system where the doped material exhibits liquid crystalline behaviour while the pure material does not. Properties of linear …
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Superconductivity of thorium hydrides and thorium deuterides
… found that Th4 H15 is a superconductor with a transition temperature near 8K, Measurements of the diamagnetic susceptibility of 24 thorium hydride and thorium deuteride samples of various compositions have been made to determine the effect of composition and of hydrogen isotope on the …
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Design of Functional Benzoxazine Materials Via Thiol-Mediated Reactions
… by both factors, resulting in broad glass transitions and mechanically fragile samples above the glass transition temperatures. Thermal stability, however, was intermediate compared to neat thiol-alkyne polymers and polybenzoxazines. The thiol-alkene polymer networks were modified by …
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Novel chiral liquid crystal organic-inorganic hybrid nanoparticle systems : Design, synthesis and investigation
… Both materials have low melting points and low transition temperatures. Phase diagrams, contact and miscibility experiments were performed in order to explain a more complicated cholesteric phase behaviour. The cholesteric mesogens were chemically attached to gold and iron/platinum …
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Synthesis of poly(arylene ether sulfone)-polyimide segmented copolymers
… high thermal stability, and high glass transition temperatures. Previously, polyimides containing pyromellitic dianhydride (PMDA) did not remain soluble in the NMP solvent during the solution imidization, but rather precipitated out of solution when partially imidized. Incorporation of …
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Irreversibility line, Hall effect, and longitudinal resistivity measurements on cobalt-doped yttrium barium(2) copper(3) oxygen(7-delta)
… annealing, we produced single crystals having transition temperatures, T$\sb{\rm c}$, comparable with those of polycrystalline samples of the same cobalt concentration.
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The relationship between the structure and physical properties of acylhydrazinatometallomesogens
… were made up in an attempt to reduce the transition temperatures of the systems. A relatively straightforward method of predicting both the transition temperatures and eutectic compositions was used and agreed well with experimentally observed transition temperatures. As a first step …
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From N to P: Examining Structure-Property Relationships of Ammonium- and Phosphonium-Containing Macromolecules
… lengths systematically decreased the glass transition temperatures of all polyelectrolytes; the larger, bulkier counterions also resulted in lower glass transition temperatures. Counterion also impacted the thermal stability of the polymerized ionic liquids with less basic counterions …
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Novel Novolac-Phthalonitrile and Siloxane-Phthalonitrile Resins cured with low melting Novolac Oligomers for Flame Retardant Structural Thermosets
… novel phthalonitrile derivatives with low glass transition temperatures, ranging from -25 to 75 ºC. Multi-functional, low molecular weight phenol-formaldehyde novolac resins were blended with these novel phthalonitrile derivatives to achieve low viscosity resin blends. Moderate temperatures and …
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Effect of heat treatment on dyeability, glass transition temperature, and tensile properties of polyacrylonitrile fibers (orlon 42)
… they were boiled in water for 15 min. The glass transition temperatures (Tg) were obtained by differential scanning calorimetry. The ratio of the intensities of the CN/CH stretching bands were found by infrared spectroscopy, using the KBr method
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Synthesis and Photopolymerization of Novel Dimethacrylates
… monomers exhibited lower viscosities and glass transition temperatures than the control, which was attributed to the elimination of the hydrogen bonding. The monomers were photopolymerized in a differential scanning calorimetry modified with an optics assembly (DPA 7; Double Beam …
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FTIR and X-ray investigation of triphenylene based discotic liquid crystals.
… observed in the liquid crystalline phase. The transition temperatures of the phase transitions were recorded to within +/-0.1 °C. Methyl additions to the ester benzoate linkage plays a major role in determining transition temperatures and also the ranges of liquid crystal phase. X-ray …
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Effects of doping on the electronic properties of niobium triselenide
… structure by CDW gap formation. Below the CDW transition temperatures, the resistivity is dominated by two types of carriers on the non-CDW band. Magnetoresistivity measurements indicate that electron-electron scattering of pockets of electrons dominates in un doped and lightly doped samples, …
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The effect of interchain transesterification reactions on the development of aromatic copolyesters
… They are limited, however, due to high temperatures required for processing and limitations on achievable mechanical properties due to the anisotropic nature of the polymer. In an attempt to address these issues, a new thermosetting polymer based on all aromatic ester units has been …
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