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 20 for “"prepolymer"”.
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Effects of Polybenzoxazine on Properties of Shape-Memory Polyurethanes with Glassy and Crystalline Soft Segments
… of the benzoxazine monomer with the PU prepolymer. The benzoxazine monomer was polymerized into PB after PU prepolymer was chain extended. The materials covered in this study were divdied into two classes, Tg-based SMPU (System I) and Tm-based (System II), respectively for glassy and …
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Controlled polymerization of alkyl vinyl ethers via 'covalent' propagating species
… and the strategy of amine functionalized prepolymer synthesis. The polymerization reactions show living behavior in nonpolar solvents at low temperatures. The observed rate of polymerization under reaction conditions is linearly dependent on the initial concentration of hydrogen iodide and …
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Synthesis and characterization of lignin-carbohydrate block copolymers
… (TDI) to form an isocyanate-capped CTA prepolymer under conditions that chain extension is limited and a sufficient NCO equivalent/mole is achieved (ie: 1 or 2). • Reaction in solution of this low DP CTA prepolymer with the HPL block. Films were directly obtained by solution casting of …
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Characterization of modified polyimide adhesives
An addition polyisoimide prepolymer was modified through the incorporation of metal particles. The response of this metal/polymer composite to mechanical vibrations and the passage of electric current was measured. Model aluminum conductor bar joints containing this material were assembled and …
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Crosslinking of cotton cellulose by lignin-isocyanate copolymer
… (TDI) in a 1:1 mole ratio. Reaction of the above prepolymer with the modified lignin (HP- EL) using a mole ratio of 1:20 to form a lignin carbamate. The lignin carbamate finish was crosslinked to cotton cellulose fabric through carbamoyl linkages when the fabric was cured. There is emperical …
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Design and fabrication of microfluidic valves using poly(N-isopropylacrylamide)
… is achieved using thermal inkjet printing of a prepolymer solution and subsequent polymerization using UV irradiation. When the gel is swollen, it blocks flow from passing through the channel. Upon heating, the gel shrinks and allows flow in the channel. Poly(NIPAAm) is a thermosensitive …
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DYNAMIC SURFACES FOR URINARY CATHETERS: THE EFFECT OF POLY (GLYCEROL SEBACATE CITRATE) COMPOSITION ON DEGRADATION, ENCRUSTATION RESISTANCE AND BACTERIAL RESPONSE
… the PGSC, the effect of N2 atmosphere on the PGS prepolymers was evaluated with Fourier-transform infrared spectroscopy (FTIR). A static N2 atmosphere was found to cause the oxidation of glycerol to glyceraldehyde and hence, preparation in a flowing N2 atmosphere was adopted. PGSC with different …
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Accessing Model, Functional Polyolefins and Polyolefin Copolymers with Ring-Opening Metathesis Polymerization
… based on the degree of saturation and the prepolymer molar mass. Appendix A shows the synthesis of similar elastomers made from polymers containing epoxide groups along the backbone of the polymer chain to explore the contributions of dangling-end defects to the mechanical properties of the …
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Novel Routes for the Design of Poly((meth)acrylic acid) Containing Polymer Structures by Controlled Radical Polymerization
… to an “on-the-spot” conversion of a hydrophobic prepolymer to a hydrophilic polymer. Further on, the combination of ATRP of EEA and the recently popularized copper(I) catalyzed “click” 1,3-dipolar cycloaddition reaction of azides and terminal alkynes was evaluated as a method to synthesize …
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Microfabrication and Evaluation of Planar Thin-Film Microfluidic Devices
… placement of a gel has been developed using a prepolymer solution with a light-sensitive initiator. Further work to adjust the polymer pore size and interface with ampholyte-containing gels should allow methods such as capillary gel electrophoresis (CGE), preconcentration, and two dimensional …
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Growth of anodic alumina nanopores and titania nanotubes and their applications
… successfully used as a template to nanoimprint prepolymer to synthesize vertically aligned and high aspect ratio h-PDMS nanorod arrays with Moiré pattern arrangements. The formation mechanism of anodic TiO2 nanotubes is proposed in this dissertation. Moreover, FIB pre-pattern guided anodization …
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Novel Novolac-Phthalonitrile and Siloxane-Phthalonitrile Resins cured with low melting Novolac Oligomers for Flame Retardant Structural Thermosets
… with 260 g mol⁻¹ novolac oligomers afforded prepolymer resins with low melt viscosities, 560 mPa s at 80 ºC. Such viscosities may allow these resins to be processed via vacuum assisted resin transfer molding (VARTM) at low temperatures and heated at elevated temperatures to produce flame …
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Two-dimensional clay and graphene nanosheets for polymer nanocomposites and energy storage applications
… better filler dispersion in polymer matrices. A prepolymer route was developed to achieve clay exfoliation in a polyurethane-vermiculite system. However, the phase-separated structure of the polyurethane matrix was disrupted. Intragallery catalysis was adopted to promote the clay exfoliation …
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Synthesis and characterization of polydimethylsiloxane-urea segmented copolymers
… precipitation of the polymer. A polyurethane prepolymer formation study done in either DMAC or o-butyrolactone (BLO) at about 105°C, showed BLO to be the better solvent. Side reactions involving isocyanate (-NCO) groups are less prevalent in BLO. ESCA was used to probe the surface chemical …
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Microfluidic synthesis and properties of bio-inspired colloids
… the solubility and diffusivity of oxygen in the prepolymer solution, thereby enhancing the rate of O₂ inhibition during microparticle synthesis. We develop a simple model that successfully predicts the augmented O₂ mass transport, which agrees well with experimental data. Encapsulating …
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Design and Fabrication of a Mask Projection Microstereolithography System for the Characterization and Processing of Novel Photopolymer Resins
… with increasing Tinuvin 400 concentration in the prepolymer?' The experiment for research question (i) revealed that achievable feature size decreases by 67% with a 420% increase in exposure energy. Introducing 0.25wt% of the photo-inhibitor Tinuvin 400 demonstrated depth of penetration reduction …
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Neuartige Schichtverbindungen zur Herstellung von Nanokompositen mit verbesserten Flammschutzeigenschaften
… Silsesquioxane Füllstoff in situ im benutzten PF-Prepolymer gebildet wurde. Der Wirkmechanismus sowie die Bildung des entstehenden Komposits wurden aufgeklärt. Aus dem eingesetzten Triethylaminopropylsilan entsteht nach Hydrolyse und Kondensation in situ ein Silsesquioxannetzwerk, das das …
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Lignin valorization
… of the final material was investigated. The prepolymer showed adhesive properties towards aluminum and its shear strength was therefore measured. The gluing properties of such synthesized glues turned out to be independent from the lignin source but affected by the amount of lignin in the …
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Influence of Electrostatic Interactions and Hydrogen Bonding on the Thermal and Mechanical Properties of Step-Growth Polymers
… chain extenders were prepared using a prepolymer method. The novel phosphonium polyurethane was more crystalline, and it was presumed that hydrogen bonding in the non-charged polyurethane restricted polymer mobility, and reduced PTMO crystallinity, and hydrogen bonding interactions were …
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Synthesis and Characterization of Poly(2-Ethyl-2-Oxazoline) Functional Prepolymers and Block Copolymers
… excellent end-group functionality may be used as prepolymers for incorporation into multiblock and graft copolymer and crosslinked structures for a variety of applications such as membranes and hydrogels for tissue engineering matrices. Poly(2-ethyl-2-oxazoline) containing block copolymers were …