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 12 of 12 for “"molecular weight control"”.
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Novel high performance thermosetting polyimides
… imide thermosetting (reactive) oligomers of controlled moleular weights were synthesized utilizing 3-phenylethynylmdine, 4-phenylethynylphthalic anhydride or phenylmaleic anhydride as the reactive endcapping agents. The phenylethynyl endcapping agents were synthesized by a ppalium-catalyzed …
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Synthesis and Characterization of Poly(2-Ethyl-2-Oxazoline) Functional Prepolymers and Block Copolymers
… such as polymerization time and temperature on molecular weight control and molecular weight distribution, endgroup functionality, living characteristics, and mechanism and kinetics. The structure of initiators was shown to significantly affect the molecular weight control and molecular weight …
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Deactivation and preparation of fused silica open tubular columns for gas and supercritical fluid chromatography
… of the synthesis procedure, simpler and better molecular weight control of the polymer, and the elimination of HC1 as a by-product of both the polymerization and endcapping steps. A new stationary phase, 7% cyanoethyl, 7% phenyl, 1% vinyl, methyl polysiloxane was synthesized and found to be more …
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Synthesis and characterization of poly(arylene ethers) and functionalized oligomers
Molecular weight control and endgroup functionalization in poly(arylene ether sulfones) has been achieved by two synthetic routes. The first utilizes DMSO/sodium hydroxide and aminophenol to introduce the amine functionality. This route, though synthetically useful, suffers from serious …
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Synthesis and characterization of high performance polybenzoxazoles
High molecular weight poly(hydroxy amide)s and polybenzoxazoles possessing a variety of backbone compositions have been synthesized via low temperature polycondensation and a novel catalytic cyclization reaction. Preliminary experiments involved the synthesis of poly(hydroxy amide)s and …
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Poly(2-alkyl-2-oxazoline) containing multiphase systems
… regard to the effects of initiator structures on molecular weight control and molecular weight distribution, living characteristics, and mechanisms and kinetics. The structure of initiators was shown to greatly affect the molecular weight control and molecular weight distribution of poly …
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Structure-property behavior of novel high performance thermoplastic and thermoset structural adhesives and composite matrix resins
… containing polyimides have been synthesized to controlled molecular weights and well-defined phthalimide endgroups via solution imidization. They were characterized by intrinsic viscosity, DSC, TGA, and thermomechanical measurements. Molecular weight control was successful and these polyimides …
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Polymerisation of vinyl monomers in continuous-flow reactors. An experimental study, which includes digital computer modelling, of the homopolymerisation of styrene and methylmethacrylate by anionic and free radical mechanisms respectively in continuous flow-stirred-tank reactors.
… of free radical and anionic polymerisation, molecular weight control in each type of polymerisation, polymerisation reactors, computer simulation of polymerisation processes and polymer characterisation by gel permeation chromatography. A novel computer model has been devised, based on the …
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Adhesion study of thermoplastic polyimides with Ti-6Al-4V alloy and PEEK-graphite composites
… polydimethylsiloxane segment incorporation and molecular weight control with non-reactive phthalimide end-groups. The adhesive bond performance of these polyimides was investigated as a function of molecular weight, siloxane incorporation, residual solvent, test temperature, and polyimide …
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Synthesis and Characterization of Responsive Poly(Alkyl Methacrylate) Topologies
… conditions, leading to significant reductions in molecular weights. The cleavable star-shaped polymers also underwent uncatalyzed degradation at elevated temperatures. Pressure-sensitive adhesive (PSA) copolymers based on 2-ethylhexyl acrylate (EHA) were synthesized containing cleavable branching …
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Metal-Free Photoredox-Mediated Ring Opening Metathesis Polymerization
… improves cost effectiveness. Additionally, low-molecular weight polymers are desirable for certain applications, such as thermosetting. We demonstrated that chain transfer with α-olefins cleaved the vinyl ether chain ends via metathesis and offered molecular weight control.
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Cresol Novolac/Epoxy Networks: Synthesis, Properties, and Processability
… excellent flame retardance. A series of linear, controlled molecular weight, 2,6-dimethylphenol endcapped cresol novolac resins have been synthesized and characterized. The molecular weight control was achieved by adjusting the stoichiometric ratio of cresol to 2,6-dimethylphenol and using an …