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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

Synthesis, characterization and application of polymeric flame retardant additives obtained by chemical modification

Sauca, Silvana 20 April 2012 (has links)
A key part of the development of new polymeric materials focuses on the use of flame-retardant additives, which help to reduce the inherent flammability of polymers and the production of smoke and toxic gases. The aim of this thesis was the preparation, characterization and application of new polymeric flame-retardant additives, which can lead to intumescent systems when mixed with ¨commodity¨ polymers. The synthesis of this kind of additives was carried out by chemical modification of different polymeric structures (alcohols, polyketones, polyaziridines) with phosphorous moieties, previously described as promoting flame retardance structures, and/or nitrogen containing moieties. The efficacy of some of these additives was tested by blending with polypropylene, one of the most commonly used thermoplastic. Flame retardancy behaviour of the blends, as well their compatibility and mechanical properties were studied, in order to observe how the flame retardant additives may affect the substrate properties. / Una parte fundamental del desarrollo de nuevos materiales poliméricos se centra en la utilización de agentes retardantes a la llama, los cuales contribuyen a reducir la inherente combustibilidad de los polímeros y la producción de humos y de gases tóxicos. El objetivo del presente trabajo ha sido la preparación, characterización y aplicación de nuevos aditivos retardantes a la llama de tipo polimérico que pueden dar lugar al mezclarse con polímeros termoplásticos de gran consumo a sistemas de tipo intumescente. La síntesis de estos additivos se ha llevado a cabo por modificación química de diferentes estructuras polimericas (alcoholes, policetonas, poliaziridinas) con compuestos fosforados, descritos previamente como promotores de retardancia a la llama y/o compuestos con nitrogeno. La eficacidad de algunos de estos additivos ha sido estudiada por mezclarse con polipropileno, uno de los más utilizados termoplasticos.
2

Synthesis and Characterization of Phosphine Oxide Containing Monomers and of the Flame Resistant Polymers Prepared Therefrom

Tchatchoua, Ngassa 05 May 2000 (has links)
This thesis has focused on the synthesis and characterization of amino functional monomers, principally monomers containing aryl phosphine oxide units. Utilization of these monomers was demonstrated in various types of linear and network polymerizations. The diamines monomers included bis(3-aminophenyl) methyl phosphine oxide (DAMPO), bis(3-aminophenyl) phenyl phosphine oxide (DAPPO), bis(3-aminophenoxy phenyl) phenyl phosphine oxide (BAPPO) and bis(3-aminophenoxy phenyl) methyl Phosphine oxide (BAMPO). From these monomers high molecular weight poly(ether imides), polyurea-urethanes, poly(arylene ether ketones) poly(arylene ether sulfones) and poly(arylene ether phosphine oxides) were. Internal and external fire testing methodologies showed that the new polymers containing phosphine oxide units were fire resistant while maintaining the desirable physical characteristics of carefully selected control systems. In addition, suitable curing schedules for epoxy networks were determined by using dielectric monitoring techniques. The curing rates varied with the structure of the monomers and were slowest for the deactivated control (4,4'aminophenyl sulfone). Epoxy networks containing aryl phosphine oxide units had higher char yields in dynamic thermogravimetric analyses than control specimens. This correlated with their superior flame resistance. The brittle epoxy matrices were subsequently modified with reactive or non-reactive thermoplastic polymers in order to improve their fracture toughness. Poly(ether imides) and poly(ether sulfones) showed good phase separation behavior with tetrafunctional epoxy matrices during the curing reactions, as confirmed by scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). Mechanical tests showed that reactive thermoplastic modification of the epoxy networks improved the fracture toughness of the systems, without noticeable decreases in other characteristics such as flexural modulus. Reactive systems also maintained chemical resistance in contrast to non-reactive thermoplastic controls. / Ph. D.

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