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Designed flame retardancy with phosphorus polymers

: Pospiech, D.; Fischer, O.; Korwitz, A.; Hoffmann, T.; Ciesielski, M.; Döring, M.; Köppl, T.; Altstädt, V.; Brehme, S.; Vollmerhausen, D.; Schartel, B.

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25th Annual Conference on Recent Advances in Flame Retardancy of Polymeric Materials 2014 : May 19-21, 2014, Stamford, Conneticut, USA
Wellesley/Mass.: BCC Research, 2014
ISBN: 1-56965-218-X
Annual Conference on Recent Advances in Flame Retardancy of Polymeric Materials <25, 2014, Stamford/Conn.>
Abstract, Elektronische Publikation
Fraunhofer LBF ()

Polymers with phosphorus-containing structural elements can form the base for REACH-conform, alternative and halogen-free flame retardants (FR’s). The past years have seen an increasing variety of polymeric structures that were designed to meet the requirements of new regulations for FR’s whose FR potential was reported using degradation, combustion, flame, fire and burning behavior. However, usually the consequences of chemical modifications for the more general property profile and the influence of addition of such FR’s on the overall property profile of the respective polymer matrix is not discussed.
Here, we will present two examples in which specially designed phosphorus polymers will be used to introduce flame retardancy in plastic materials.
Example 1 concerns FR in high performance epoxy resins. Here, phosphorus-containing poly(aryl ether)s were developed for use as combined toughness modifiers/FR’s. The influence of structural variations on the
decomposition and combustion including degradation pathways will be shown and the FR performance in cured epoxy formulations will be discussed concluding that polysulfones with DOPO-substituents mixed with standard PSU provided optimum results.
Example 2 will show two series of phosphorus-containing polyesters designed to enhance flame retardancy in poly(butylene terephthalate) (PBT). Again, the influence of variations in the chemical structure on solid state structure, decomposition and combustion will be discussed. In all structures, the phosphorus is incorporated in the substituent which results in each case in the loss of crystallinity and thus, reduction of toughness of the materials. However, the FR efficiency is demonstrated to be high, which could be maintained also in PBT using the P-polymers as additives. In these blends, roughly the level of the commercial benchmark was achieved.
Finally, the additional use of nanocomposite formation of the polyesters with organophilically modified clays or multiwalled carbon nanotubes, respectively, to further enhance the flame retardancy of polyester materials will be discussed. While addition of only nanomaterials did not yield a dramatic positive effect, combination of both nanomaterial and phosphorus polyester additive provided an additional reduction effect on total heat evolved and effective heat of combustion. It can be summarized that work with polymeric FR’s seems to be very promising, although much effort to optimize the systems and get the maximum effects will be necessary in future.