A promising strategy for enhancing fire resistance of steel structure: a composite thermoplastic polyurethane sheet adhered to steel plate

It is an effective passive fire protection method for the steel structure by painting fireproof coatings. Here, a feasible strategy for enhancing the fire resistance of steel structures is proposed. Specifically, a kind of adhesive composite sheet based on thermoplastic polyurethane (TPU), ammonium polyphosphate (APP), polyhedral oligomeric octaphenylsilsesquioxane (OPS), titanium dioxide (TiO₂) and sodium silicate was constructed and named as Sheet-Ti/Na. The as-prepared Sheet-Ti/Na exhibited excellent flame retardancy and smoke suppression performance. In addition, the Sheet-Ti/Na can firmly adhere to the steel plate through hot pressing and adhesive bonding methods, acting as a non-traditional fireproof “coating”. This feasible coating method can effectively enhance the fireproof and thermal insulation of the steel plates under the action of the hydrocarbon fire at about 1100 ℃. After testing, the char layer of Sheet-Ti/Na can still firmly adhere to the steel plate without any detachment or cracking. Finally, a ceramic-like reaction among TiO₂, APP, OPS and sodium silicate to generate pyrophosphates (TiP₂O₇ and SiP₂O₇) was clarified. The thermal insulation, flame retardancy and smoke suppression mechanisms of the Sheet-Ti/Na system also were stated. This work offers a promising strategy for rapidly and efficiently preparing fireproof and thermal insulation “coatings” for steel structures.