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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 37 for “"polysiloxane"”.
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Molecular Dynamic Simulation of Polysiloxane
… traditional sintering methods do not allow for. Polysiloxanes are commonly used as a precursor for these types of material because of their highly tunable microstructures by adjusting the side groups on the initial polymer. These Polymers are generally cross linked and pyrolyzed in inert …
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Polysiloxane-polyarylester block copolymers: synthesis and characterization
… structures. Relatively high molecular weight polysiloxane-polyarylester block copolymers were prepared by two different synthetic routes. A solution technique was used to synthesize well-defined, perfectly alternating block copolymers by reacting a difunctional silylamine—terminated siloxane …
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Gas permeability of polyimide/polysiloxane block copolymers
… dimethylbenzyl)benzene (Bis P). The polysiloxane was an aminopropyl terminated poly(dimethylsiloxane). Randomly segmented block copolymers of =20 wet. % poly(dimethylsiloxane) with different segment lengths were also studied, based on the same materials for the sake of comparison with …
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The investigation of some novel polysiloxane liquid crystal systems.
… and characterised. These have been attached to polysiloxane systems to form ring, linear and elastomeric polymer liquid crystals. 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 …
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Fabrication, characterisation and properties of polysiloxane rice husk silica composites
The polysiloxane silica composites were fabricated and characterised as to elucidate the feasibility of casting (CA) and compression (CO) method. Besides, the contribution of rice husk silica (RHA SiO2) and crystalline silica (CS) in enhancing the composites properties were also investigated. …
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A study of polyethylene oxide-polysiloxane networks as biomaterials for drug release
Thesis (Ph. D.)--Massachusetts Institute of Technology, Harvard-MIT Division of Health Sciences and Technology Program in Medical Engineering and Medical Physics, 1989.
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Polysiloxane-based liquid crystal block copolymers for piezoelectric and mechano-optical applications
Liquid crystal research has gained interest in a wide range of applications that go beyond displays. Some of these applications include memory devices, sensors, and variable light valves. Currently, liquid crystals in the form of small molecules are capable of exhibiting fast response times; …
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Synthesis and characterization of novel polyester/polysiloxane and polyester/arylphosphine oxide copolymers
… copolymerization. The molecular weight of the polysiloxane and chemical composition of the copolymer were systematically varied to prepare a series of segmented polyester / poly(dimethylsiloxane) copolymers.
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Synthesis of Functionalized Polysiloxanes and Investigation of Highly Filled Thermally Conductive Microcomposites
… nitrile and carboxylic acid moieties. Such polysiloxanes were prepared with controlled concentrations of both the polar moieties and hydrido or vinyl pendent crosslinkable sites to afford precursor materials for well-defined networks. The intention was to generate stable microcomposite …
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Improved Fabrication and Quality Control of Substrate Integrated Microelectrode Arrays
… use of MMEPs. The major problems include (1) polysiloxane insulation deterioration and breakdown, (2) and loss of gold at the gold electroplated indium-tin oxide (ITO) electrodes. The objective of this investigation was to correct these major problems. Quality control measures were employed to …
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Deactivation and preparation of fused silica open tubular columns for gas and supercritical fluid chromatography
… In the synthesis of intermediate polarity polysiloxane stationary phases, mixtures of commercially available cyclic siloxanes were shown to be a viable alternative to the use of dichlorosilanes as starting material. The main advantages were the simplification of the synthesis procedure, …
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Surface characterization of LDEF materials
… the polymer systems, such as Kapton®, polyimide polysiloxane copolymers, and fluorinated ethylene propylene thermal blankets on the backside of the LDEF revealed significant changes in both the surface composition and surface chemistry as a result of exposure to the low-Earth orbit environment. …
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Synthesis and Characterization of Nitrile Containing Polysiloxanes and Their Corresponding Networks as Aircraft Sealant Materials
Polysiloxane networks have excellent oxidative and good UV environmental stability, flexibility at low temperatures, and thermal stability at higher temperatures. This wide service temperature range makes these materials a candidate class of materials for high performance adhesives and sealants, …
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Silicon-based organic and inorganic polymers
… silica (SiO₂), to linear high molecular weight polysiloxanes which display properties of both organic and inorganic materials. Part 1 of this dissertation describes the synthesis of three-dimensional inorganic SiO₂ networks and organic-inorganic hybrid networks using a low temperature solution …
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Synthesis and Characterization of Cycloaliphatic and Aromatic Polyester/Poly(dimethylsiloxane) Segmented Copolymers
… and hydrophobic surface modification. The polysiloxane segment was effeciently incorporated into the copolymers and was unaffected by the transesterification catalyst under typical reaction conditions. The homopolymers and copolymers were characterized by solution, thermal, and mechanical, …
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A study of a flapping flag in viscoelastic fluids and its implications for micro-scale swimming in biofluids
… dynamics in these biological fluids. A slender polysiloxane rod was placed in a rotating annulus filled with a cetyl pyridnium chloride micellar solution and also with a xanthan gum solution. Flapping of the rod was observed with the micellar solution for Weissenberg numbers greater than 1, …
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Palladium-catalyzed PMHS reductions of imines
… solution result in the formation of polysiloxane encapsulated Pd-nanoparticles, and we were able to confirm the existence of these nanoparticles using transmission electron microscopy (TEM). The crucial role of KF was confirmed on these studies; without addition of KF agglomeration of …
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Study of Pore Development in Silicon Oxycarbide Ceramics to Understand the Microstructural Evolution
… In this thesis, SiOC is fabricated using a base polysiloxane polymer using different gases during heating, different additives that change the initial polymer chemical composition or polymer shape, and polymers with different reactive groups. Porosity was introduced into the SiOC ceramics through …
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Photo-responsive liquid crystal block copolymers/
… azobenzene nematic side chain (SC) LC polysiloxane was developed, characterized, and demonstrated to respond significantly, and reversibly from 0-50°C, which is the ambient temperature range in which we live, through its photo-induced nematic to isotropic transition. In particular, its …
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Siloxane-Based Reinforcement of Polysiloxanes: from Supramolecular Interactions to Nanoparticles
Polysiloxanes represent a unique class of synthetic polymers, employing a completely inorganic backbone structure comprised of repeating –(Si–O)n– 'siloxane' main chain linkages. This results in an assortment of diverse properties exclusive to the siloxane bond that clearly distinguish them from …
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