Alexander Battig, BAM (German Federal Institute for Materials Research and Testing), presented research into development of hyperbranched polymeric FRs, containing phosphorus, nitrogen and sulphur (phosphorus esters, amidates, diamidates, amides). The polymer molecules may be functionalised both at molecule ends and within the polymer backbone. The hyperbranched polymers have the advantage of being non crystalline, so improving immobilisation in the polymer matrix, and compatibility with mechanical properties, particularly in epoxy resins. A systematic variation of P-O and P-N content highlighted the change in fire performance of the FRs. Low thermal stability of low molar mass variants was improved with hyperbranching and may be further improved by inclusion of aromatic groups. Sulphur showed to act to improve fire resistance both in the gas phase (radical generator) and the solid phase (char enhancer). The results illuminate the multifunctional qualities of hyperbranched polymers as effective FRs.
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