Maude Jimenez, UMET Lille University, France, presented investigations of self-stratifying epoxy/silicone coatings, with the aim of achieving railway fire safety requirements. The principle of self-stratification is to create a multi-layered coating in a one-pot application, that brings both adhesion to the substrata, surface finishing and flame retardancy. A range of different resins, green solvents and curing temperatures were tested, including bio-based resins. Liquid (RDP, BDP) and solid flame retardants (clays, starch, phosphates, etc.) were tested. These mostly showed to not negatively impact stratification. Durability of the coating, UV resistance and aesthetic / handling properties were assessed, showing that reliable PIN flame retardant formulations can be achieved. Life cycle analysis suggested that bio-based resins were preferable.
Séverine Bellayer, UMET Lille University, France, presented sol-gel application of a transparent PIN flame retardant formulation to wood, using different silica precursors, such as tetraethoxysilane and (3-Aminopropyl)triethoxysilane, in a mix with diethylphosphite in water solution. Dip impregnation treatment of the wood resulted in a 80 µm coating, versus 800 µm by sol-gel. The dip impregnation did not significantly improve the fire performance of the wood, with cracks showing in char. The sol-gel application resulted in a dense char layer, without cracks, and showed improved fire performance and thermal protection of the wood.
Sylvie Rossignol, IRCER (Institute of Ceramics), Limoges, France, overviewed current knowledge of geopolymers as fire resistant materials or coatings. Geopolymers are alumino-silicate inorganic polymers. For example, mined argillite has been successfully tested as a PIN FR coating or as a fire-resistant barrier material up to 1200°C. A scale up process to synthetised plate was successfully performed.