Researchers developed a new kind of flame-retardant coating using renewable, nontoxic materials readily found in nature. The coating could provide more effective fire protection for several widely used materials. The coatings offer the opportunity to reduce the flammability of polyurethane foam used in a variety of furniture.
In nature, both cellulose (a component of wood and various sea creatures) and clay (a component in soil and rock formations) act as mechanical reinforcements for the structures in which they are found. These ingredients are used to make a heat-shielding or flame-retardant coating as a multilayer thin film deposited from water.
Among the benefits gained from using this method include the coating's ability to create an excellent oxygen barrier to plastic films — commonly used for food packaging — and better fire protection at a lower cost than other, more toxic ingredients traditionally used in flame-retardant treatments.
To test the coatings, researchers applied it to flexible polyurethane foam — often used in furniture cushions — and exposed it to fire using a butane torch to determine the level of protection the compounds provided. While uncoated polyurethane foam immediately melts when exposed to flame, the foam treated with the new coating prevented the fire from damaging any further than surface level, leaving the foam underneath undamaged.
The nanobrick wall structure of the coating reduces the temperature experienced by the underlying foam, which delays combustion. The coating also serves to promote insulating char formation and reduces the release of fumes that feed a fire.