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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Untersuchungen zum Abbauverhalten von Polyestern mit unterschiedlichen Phosphorsubstituenten

Fischer, Oliver 29 January 2014 (has links) (PDF)
In unserem alltäglichen Leben nehmen Kunststoffe eine immer größere Rolle ein. Die organische Struktur dieser Materialien bedingt die Brennbarkeit derselbigen und birgt somit eine Gefahr, die allgegenwärtig ist. Flammschutz von Polymeren ist daher eine wichtige Eigenschaft. Der Markt an Flammschutzadditiven ist bereits sehr breit gefächert. Allerdings gibt es nur wenig Studien, die systematisch Struktur und Flammschutzwirkung betrachten. So war es das Ziel dieser Arbeit, durch die Untersuchung zweier systematisch variierter Polymergruppen Struktur-Eigenschafts-Beziehungen zu entwicklen, die das Verständnis von Flammschutzadditiven erweitern. Die erste Gruppe bestand aus Polyestern mit einem gleichbleibenden Polymerrückrat an dem phosphorhaltige Seitenketten systematisch variiert wurden. In der zweiten Gruppe wurde das Polymergrundgerüst bei gleichbleibendem Substituenten variiert. Die Strukturen wurden umfassend hinsichtlich ihres Abbaus untersucht, so das durch Korrelation von Abbauverhalten und erarbeiteten Abbaumechanismen Zusammenhänge zwischen der nativen Polymerstruktur und dem Flammschutzverhalten gefunden werden konnten. Es lässt sich nachweisen, dass das Hauptabbaumaximum fast vollständig durch die Polymergrundkette dirigiert wird. Der Substituent hat wenig Einflauss darauf, womit sich die Möglichkeit ergibt Flammschutzadditive gezielt and das Abbaumaximum des zu schützenden Matrixpolymers anzupassen. Die strukturelle Veränderung des phosphorhaltigen Substituenten hingegen ermöglich es das Flammschutzadditv in seiner Wirkungsweise, also Aktivität in der Gasphase oder kondensierten Phase, anzupassen. Sehr wesentlich, besonders mit Blick auf die Rückstandbildung, ist das Zusammenspiel zwischen Substituent und Polymerrückgrat. Bei geeigneter Wahl aliphatischer und aromatischer Anteile lassen sich so Flammschutzadditive herstellen, die einerseits gut zu verarbeiten sind, andererseits aber auch einen möglichst hohen Rückstand erzeugen. Mit Kenntnis dieser Struktur-Eigenschafts-Beziehungen ist es zukünftig möglich, polymere Flammschutzadditive zielgerichteter zu entwickeln. So lässt sich das Additiv in seiner Wirkung nicht nur an das Matrixpolymer anpassen, sondern auch an die primären Brandgefahren in dessen Endanwendung. Eine Under-the-hood-Anwendung im Automobilbau fordert andere Flammschutzeigenschaften als die Verwendung im häuslichen Küchenbedarf.
2

Phosphorus-Containing Polymers, Their Blends, and Hybrid Nanocomposites with Poly(Hydroxy Ether), Metal Chlorides, and Silica Colloids

Wang, Sheng 13 April 2000 (has links)
Phosphorus-containing high performance polymers have been extensively studied during the last 10 years. These materials are of interest for a variety of optical and fire resistant properties, as well as for their ability to complex with the inorganic salts. This dissertation has focused on the nature of the phosphonyl group interactions with hydroxyl containing polymers, such as the poly(hydroxy ether)s. These may be considered linear models of epoxy resins and are also closely related to dimethacrylate (vinyl ester) matrix resins that are important for composite systems. It has been shown that bisphenol A poly(arylene ether phosphine oxide/sulfone) homo- or statistical copolymers are miscible with a bisphenol A-epichlorohydrin based poly(hydroxy ethers) (PHE), as shown by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC), infrared spectroscopy and , solid state cross polarization-magic angle spinning nuclear magnetic resonance (CP-MAS). These measurements illustrate the strong hydrogen bonding between the phosphonyl groups of the copolymers and the pendent hydroxyl groups of the PHE as the miscibility inducing mechanism. Complete miscibility at all blend compositions was achieved with as little as 20 mole% of phosphine oxide units in the poly(arylene ether) copolymer. Replacement of the bisphenol A moiety by other diphenols, such as hydroquinone, hexafluorobisphenol A and biphenol did not significantly affect blend miscibilities. Miscible polymer blends with PHE were also made by blending poly(arylene thioether phosphine oxide), and fully cyclized phosphine oxide containing polyimides based on (prepared from 2,2'-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) and bis(m-aminophenyl) methyl phosphine oxide (DAMPO)) or bis(m-aminophenyl) phenyl phosphine oxide). Additional research has focused on the influence of these materials on the property characteristics of vinyl ester matrix resins and has shown that the concentration of phosphonyl groups controls the homogeneity of both oligomers and the resulting networks. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and fracture toughness measurements further confirmed the qualitative observations. Metal salts, such as CoCl2 and CuCl2 had earlier been demonstrated to form complexes/nanocomposites with phosphorus-containing poly(arylene ethers). It has been possible to prepare transparent films with 100 mol% of metal chlorides, based upon the phosphonyl groups. The films are transparent, unlike the opaque polysulfone control systems. FTIR results suggested the formation of inorganic salt and polymer complexes at low concentrations. TEM showed homogeneous morphology at low concentrations and excellent dispersion even at high mole % of salts. Cobalt materials reinforce the basic poly(arylene ether)s to provide higher modulus values and influence positively the char yield generated after TGA experiments in air. The cobalt salt/BPADA-DAMPO polyimide composites also yield transparent films, implying very small dimensions. Silica-polymer nanocomposites were also produced by mixing commercial silica colloid/N,N-dimethylacetamide (DMAc) fine dispersions (~ 12 nm) with bisphenol A poly(arylene ether phenyl phosphine oxide). The dry films produced by solution casting are transparent and silica colloids are evenly dispersed (~ 12 nm) into the polymer matrix as shown by TEM. These nanocomposites increased char yield compared with the polymer control, suggesting their fire retardant character. In comparison, the silica/polysulfone hybrid films prepared by the same methods were opaque and the char yield was not improved. This different phase behavior has been explained to be due to the hydrogen bonding between phosphonyl groups and silanol hydroxyl groups on the surface of the nanosilica. / Ph. D.
3

Untersuchungen zum Abbauverhalten von Polyestern mit unterschiedlichen Phosphorsubstituenten

Fischer, Oliver 05 December 2013 (has links)
In unserem alltäglichen Leben nehmen Kunststoffe eine immer größere Rolle ein. Die organische Struktur dieser Materialien bedingt die Brennbarkeit derselbigen und birgt somit eine Gefahr, die allgegenwärtig ist. Flammschutz von Polymeren ist daher eine wichtige Eigenschaft. Der Markt an Flammschutzadditiven ist bereits sehr breit gefächert. Allerdings gibt es nur wenig Studien, die systematisch Struktur und Flammschutzwirkung betrachten. So war es das Ziel dieser Arbeit, durch die Untersuchung zweier systematisch variierter Polymergruppen Struktur-Eigenschafts-Beziehungen zu entwicklen, die das Verständnis von Flammschutzadditiven erweitern. Die erste Gruppe bestand aus Polyestern mit einem gleichbleibenden Polymerrückrat an dem phosphorhaltige Seitenketten systematisch variiert wurden. In der zweiten Gruppe wurde das Polymergrundgerüst bei gleichbleibendem Substituenten variiert. Die Strukturen wurden umfassend hinsichtlich ihres Abbaus untersucht, so das durch Korrelation von Abbauverhalten und erarbeiteten Abbaumechanismen Zusammenhänge zwischen der nativen Polymerstruktur und dem Flammschutzverhalten gefunden werden konnten. Es lässt sich nachweisen, dass das Hauptabbaumaximum fast vollständig durch die Polymergrundkette dirigiert wird. Der Substituent hat wenig Einflauss darauf, womit sich die Möglichkeit ergibt Flammschutzadditive gezielt and das Abbaumaximum des zu schützenden Matrixpolymers anzupassen. Die strukturelle Veränderung des phosphorhaltigen Substituenten hingegen ermöglich es das Flammschutzadditv in seiner Wirkungsweise, also Aktivität in der Gasphase oder kondensierten Phase, anzupassen. Sehr wesentlich, besonders mit Blick auf die Rückstandbildung, ist das Zusammenspiel zwischen Substituent und Polymerrückgrat. Bei geeigneter Wahl aliphatischer und aromatischer Anteile lassen sich so Flammschutzadditive herstellen, die einerseits gut zu verarbeiten sind, andererseits aber auch einen möglichst hohen Rückstand erzeugen. Mit Kenntnis dieser Struktur-Eigenschafts-Beziehungen ist es zukünftig möglich, polymere Flammschutzadditive zielgerichteter zu entwickeln. So lässt sich das Additiv in seiner Wirkung nicht nur an das Matrixpolymer anpassen, sondern auch an die primären Brandgefahren in dessen Endanwendung. Eine Under-the-hood-Anwendung im Automobilbau fordert andere Flammschutzeigenschaften als die Verwendung im häuslichen Küchenbedarf.
4

Novel phosphorus containing poly(arylene ethers) as flame retardant additives and as reactant in organic synthesis

Satpathi, Hirak 13 August 2015 (has links) (PDF)
Due to their outstanding properties, poly(arylene ethers) are useful as toughness modifiers in epoxy resins (EP). Furthermore, these polymers show rather low intrinsic fire risks. According to recent research it has been incorporated that poly(arylene ether phosphine oxides) [PAEPO’s] can further improve the fire behavior. Increasing phosphorous content of the PAEPO can influence the fire behavior too. Fire retardants containing phosphorus – regardless of whether an additive or reactive approach is used – show different mechanisms in the condensed and gas phase. In the present study PSU Control (BPA based polysulfone) with four different PAEPO’s and their corresponding blends with an EP were investigated. All poly(arylene ether phosphine oxides) were synthesized by nucleophilic aromatic polycondensation. The polymers obtained covered a wide range of weight average molar masses (6,000 – 150,000 g/mol) as determined by size exclusion chromatography with multi-angle light scattering detection (MALLS). FTIR, NMR spectroscopy and MALDI-TOF revealed formation of the desired polymer structure of the linear poly(arylene ethers). All polymers were easily soluble in common organic solvents, thus enabling processing from solution.The pyrolysis and the fire retardancy mechanisms of the polymers and blends with epoxy resin (EP) were tackled by means of a comprehensive thermal analysis (thermogravimetry (TG), TG-evolved gas analysis) and fire tests [PCFC, limiting oxygen index (LOI), UL-94, cone calorimeter]. The Mitsunobu reaction of Dimethyl-5-hydroxyisophthalate and a long chain semifluorinated alcohol requires triphenyl phosphine as a reactant. Identical, in some case higher yield was obtained in the usual conditions, with triphenyl phosphine and with trivalent phosphorus containing polymers, which was prepared in solvent free bulk (melt) polymerization technique from trivalent phosphorus monomer and a silylated diphenol in presence of CsF. Purification and the recovery of the final product which is always a big challenge in case of Mitsunobu reaction, was far more easier using polymer compared to triphenyl phosphine. During polymerization there was a possibility to have polymer having repeating unit containing both trivalent phosphorus and phosphine oxide. The trivalent phosphorus content of the polymer can be varied using different molar concentration of CsF.
5

Novel phosphorus containing poly(arylene ethers) as flame retardant additives and as reactant in organic synthesis

Satpathi, Hirak 08 June 2015 (has links)
Due to their outstanding properties, poly(arylene ethers) are useful as toughness modifiers in epoxy resins (EP). Furthermore, these polymers show rather low intrinsic fire risks. According to recent research it has been incorporated that poly(arylene ether phosphine oxides) [PAEPO’s] can further improve the fire behavior. Increasing phosphorous content of the PAEPO can influence the fire behavior too. Fire retardants containing phosphorus – regardless of whether an additive or reactive approach is used – show different mechanisms in the condensed and gas phase. In the present study PSU Control (BPA based polysulfone) with four different PAEPO’s and their corresponding blends with an EP were investigated. All poly(arylene ether phosphine oxides) were synthesized by nucleophilic aromatic polycondensation. The polymers obtained covered a wide range of weight average molar masses (6,000 – 150,000 g/mol) as determined by size exclusion chromatography with multi-angle light scattering detection (MALLS). FTIR, NMR spectroscopy and MALDI-TOF revealed formation of the desired polymer structure of the linear poly(arylene ethers). All polymers were easily soluble in common organic solvents, thus enabling processing from solution.The pyrolysis and the fire retardancy mechanisms of the polymers and blends with epoxy resin (EP) were tackled by means of a comprehensive thermal analysis (thermogravimetry (TG), TG-evolved gas analysis) and fire tests [PCFC, limiting oxygen index (LOI), UL-94, cone calorimeter]. The Mitsunobu reaction of Dimethyl-5-hydroxyisophthalate and a long chain semifluorinated alcohol requires triphenyl phosphine as a reactant. Identical, in some case higher yield was obtained in the usual conditions, with triphenyl phosphine and with trivalent phosphorus containing polymers, which was prepared in solvent free bulk (melt) polymerization technique from trivalent phosphorus monomer and a silylated diphenol in presence of CsF. Purification and the recovery of the final product which is always a big challenge in case of Mitsunobu reaction, was far more easier using polymer compared to triphenyl phosphine. During polymerization there was a possibility to have polymer having repeating unit containing both trivalent phosphorus and phosphine oxide. The trivalent phosphorus content of the polymer can be varied using different molar concentration of CsF.

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