A polymer (poly((3,3’-diphenyl diacetylethylenediamino)-1,1’-ferrocene) = PDPFDE) was synthesised linking ferrocene, aromatic carbon rings and the nitrogen compound ethylenediamine. It is know that the iron-containing organic compound, ferrocene (cyclopentaienyl ring) can improve fire safety by smoke suppression and char formation. The ferrocene polymer here developed is shown to self-char (carbon source) and to reduce smoke. The nitrogen links are flexible, giving a plasticiser effect, as well as releasing nitrogen gases in fire. In a 2019 paper, the PDPFDE polymer was tested with APP / PER (ammonium polyphosphate / pentaerythritol) intumescent PIN FR in polypropylene. Results show that 0.5 – 1 % ferrocene polymer increased LOI and reduced heat release rate beyond that achieved with APP/PER alone, improved char structure and enabled UL94-V0 (4 mm) whereas APP/PER alone only achieved UL94-V1. Higher loads of the ferrocene polymer reduced performance, probably by catalysis of polypropylene degradation in fire. The ferrocene polymer also improved the polypropylene mechanical properties (impact strength, elongation at break). In a previous paper (2017), PDPFDE was tested at 5% loading in DGBDA/m-PDA epoxy at 5% achieved UL94-V1 (3.2 mm) and reduced peak heat release rate by 36% and total smoke production by 24% compared to neat epoxy.
“Synergistic improvement of fire retardancy and mechanical properties of ferrocene‐based polymer in intumescent polypropylene composite”, W-X. Li et al., Polym Adv Technol. 2019, 1–12, https://doi.org/10.1002/pat.4687
“Ferrocene‐based non‐phosphorus copolymer: synthesis, high‐charring mechanism and its application in fire retardant epoxy resin”, D Liao et al., Ind Eng Chem Res. 2017, 56(44): 12630‐12643, https://doi.org/10.1021/acs.iecr.7b02980