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Hyperbranched Polymeric Flame Retardants: The Role of Chemical Composition and Complex Shape

  • The need to develop effective flame retardants that retain polymer properties and are safe for consumers and the environment is a continuous challenge for material scientists. While halogenated flame retardants were once commonplace, the shift to non-halogenated materials has steadily progressed due to concerns over impact on health and the environment. One prominent group of flame retardants has become a viable alternative for halogenated materials, namely phosphorus-based flame retardants. The chemical versatility of phosphorus-based flame retardants and the ability to work as reactive or additive compounds makes them ideally suited for modern materials. There exists a trend toward complex, polymeric, and multifunction flame retardants, as these materials show greater flame retardancy performance than low molecular weight counterparts and affect material properties to a much lesser extent. One group of organophosphorus flame retardants that shows great potential forThe need to develop effective flame retardants that retain polymer properties and are safe for consumers and the environment is a continuous challenge for material scientists. While halogenated flame retardants were once commonplace, the shift to non-halogenated materials has steadily progressed due to concerns over impact on health and the environment. One prominent group of flame retardants has become a viable alternative for halogenated materials, namely phosphorus-based flame retardants. The chemical versatility of phosphorus-based flame retardants and the ability to work as reactive or additive compounds makes them ideally suited for modern materials. There exists a trend toward complex, polymeric, and multifunction flame retardants, as these materials show greater flame retardancy performance than low molecular weight counterparts and affect material properties to a much lesser extent. One group of organophosphorus flame retardants that shows great potential for high-performance polymers like epoxy resins are hyperbranched phosphorus-based polymers. These additives exhibit great miscibility with the polymer matrix and a significantly decreased diffusion through the material, which greatly reduce leaching or blooming out of the matrix. Moreover, the material’s thermal stability remains intact at elevated temperatures due to its low impact on the glass transition temperature. Finally, following market trends and legislation such as the guidelines for the Restriction of Hazardous Substances Directive implemented by REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) in the EU, these macromolecules are non-accumulating, non-toxic and have a lower risk of leeching or blooming from the matrix, further reducing environmental impact. The work presented herein focusses on two distinct parts studying hyperbranched polymeric flame retardants and their corresponding monomeric compounds. The first part, involving the low molecular weight components, investigated the role of the chemical surrounding of phosphorus in terms of flame retardant efficacy. Here, a systematic variance of the surrounding of phosphorus was investigated: by changing the ratio of oxygen to nitrogen (4:0 until 1:3), four materials, namely phosphoester (4:0), phosphoramidate (3:1), phosphorodiamidate (2:2), and phosphoramide (1:3), were synthesized, characterized, and finally added to Bisphenol A based epoxy resins (10 wt.-% loading). Pyrolysis investigations showed that low molecular weight components volatize at lower temperatures than the polymer matrix. Additionally, cone calorimeter measurements and TGA-FTIR investigations show trends in respect to FR efficacy in pyrolysis and full flaming conditions. The second part involves the hyperbranched variants of the monomeric counterparts and investigates the role of complex shape on flame retardant efficacy. By comparing the low to the high molecular weight compounds, the influence of the complex shape becomes apparent and can be quantified. Cone calorimeter measurements show an increase in flame retardancy for some materials, while for others, the mode of action is altered. By implementing a multi-methodical approach, various flame retardancy aspects, from pyrolysis behavior in the gas and condensed phase, to ignitability / reaction-to-small-flame performance, to action in forced flammability experiments, are identified and quantified, allowing for a clearer understanding of the behavior in fire of these novel flame retardants. By comprehending the roles of chemical composition and complex shape, it opens the path for new and effective multifunctional, polymeric flame retardants with decreased PBT, higher miscibility, and low impact on Tg. This work is funded by the Deutsche Forschungsgemeinschaft (DFG: SCHA 730/15-1; WU 750/8-1).zeige mehrzeige weniger

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  • MoDeSt 2018 Tokyo Presentation _final.pdf
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Metadaten
Autor*innen:Alexander Battig
Koautor*innen:J. Markwart, F.R. Wurm, Bernhard Schartel
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2018
Organisationseinheit der BAM:7 Bauwerkssicherheit
7 Bauwerkssicherheit / 7.5 Technische Eigenschaften von Polymerwerkstoffen
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurbau
Freie Schlagwörter:Flame retardant; Hyperbranched polymer; Phosphoester; Phosphoramidate; Phosphorodiamidate; Pphosphoramide
Themenfelder/Aktivitätsfelder der BAM:Infrastruktur
Infrastruktur / Fire Science
Veranstaltung:10th International Conference on Modification, Degradation and Stabilization of Polymers, MoDeSt2018
Veranstaltungsort:Tokyo, Japan
Beginndatum der Veranstaltung:02.09.2018
Enddatum der Veranstaltung:06.09.2018
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:19.09.2018
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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