Water-based flame retardant coating using nano-boehmite for expanded polystyrene (EPS) foam

Expanded polystyrene (EPS) foam has been successfully flame retarded by a water-based coating containing nanoparticles of boehmite and poly(vinyl alcohol) (PVOH) as chat former. Boehmite enhances the charring of PVOH. The influence of suspension viscosity, coatings number, impregnation time and drying method was studied to monitor the amount of coating deposited and the coating thickness. The coating suspension is able to penetrate into the core of the foam. EPS without hexabromocyclododecane (HBCD) is upgraded from F to E rating according to the NF EN ISO 11925-2 standard when the penetration of coating suspension into the core is high enough, due to the formation of a char layer reinforced by nano-boehmites even if EPS does not shrink away from the flame. (C) 2016 Elsevier B.V. All rights reserved.