Maxinne Denis, University of Montpellier, France, presented testing of bio-based PIN flame retardants for alkyd resin coatings. Alkyd resins are widely used in solvent-based paints and coatings, but are flammable (including after application) and leave solvent residues from the application process. A bio-based flame retardant was produced by phosphorylation of cardanol, a waste from cashew nut processing. This showed to be effective in a 60 µm alkyd resin coating, bonding to the resin and reacting to reduce solvent residues. With 2% phosphorus in the cardanol, >40% reduction in peak heat release rate was achieved compared to resin without cardanol inclusion.
Jean-Valère Lorenzetti, SPE Corsica University, presented tests of plant extracts containing polyphenols, from local forestry wastes, as a possible replacement of pentaerythritol in intumescent PIN flame retardant coatings (with APP ammonium polyphosphate and melamine). Performance was not as good as pentaerythritol but potentially promising. He emphasised the need to ensure fire safety treatment of secondary structures such as wooden fences or decking with the increasing challenge of wildfires.
David De Smet, Centexbel, Belgium, summarised trials of different bio-based PIN flame retardants on various textiles. Centexbel is the Belgian centre for research and technical development in textiles, since 1947. Bio-based molecules tested included amino acids, glycerol, sugars and ATP (adenosine tri phosphate). Bio-derived sorbitol or isosorbitol include OH groups to which phosphorus was bonded from phosphoric acid. The resulting compounds were tested as PIN flame retardants for cotton fibres, showing fire resistance to ISO 15025 (limited flame spread) after 5 wash cycles at 40°C. Polyphosphate vanillin showed to be effective as a PIN flame retardant for 2K polyurethane (PU) coated PET fibres (polyethylene terephthalate). The resulting FR coated fabrics complied to ISO 15025 (limited flame spread of 2 seconds), while 2K PU coated PET fabrics without FR completely burnt. The coated fabrics could be washed at 40°C and 60°C.
Claire Negrell, ICGM Montpellier, presented bio-sourced eugenol and isoeugenol as building blocks for PIN flame retardant polymers (by functionalisation with e.g. phosphorus) or for epoxy cross-linking.
Valentin Carretier, Mines Alès, presented a combination of lignin nano-particles, APP (ammonium polyphosphate) and zinc compounds as a PIN flame retardant solution for 3D printing (see J-M. Lopez Cuesta presentation).
Marcos Batistella, Mines Alès, presented tests of specific fractions of fly ash (from municipal refuse incineration) as a synergist for phosphorus – nitrogen PIN flame retardants in PLA.