Carbon nanotubes used to create a flame-retardant coating for furniture
By Ben Coxworth
January 16, 2014
Your furniture could kill you. According to the US National Fire Protection Association, nearly 20 percent of home fire deaths between 2006 and 2010 occurred in fires where upholstered furniture was the first item to ignite. It's actually not so much the exterior fabric that burns, as it is the foam beneath it. With that in mind, scientists at the National Institute of Standards and Technology (NIST) have used carbon nanotubes to create a coating for that foam, that reduces its flammability by 35 percent.
The coating was made by inserting a layer of the heat-dissipating nanotubes between two layers of polymer, then stacking four of those three-layer sandwiches to form one sheet. Despite the fact that it's made up of a total of 12 layers, that sheet has a thickness of less than one-hundredth the diameter of human hair.
Initially, it was difficult getting the nanotubes to adhere to the polymer, causing them to be distributed unevenly between the two sheets. In order to make them stickier, the scientists attached nitrogen-containing molecules known as amine groups to the nanotubes. The same technique is used when working with cell cultures, in order to make DNA molecules stay put.
When polyurethane foam samples treated with the coating were tested in the lab, they were found to be significantly more resistant to ignition and burning than samples treated with retardants that are now commonly used on furniture. Additionally, when exposed to a flame, the coating produced a protective layer of char that helped keep the foam from melting and pooling – when soft furniture does catch fire, pools of burning molten foam can make the situation much worse.
The research was conducted chiefly by materials scientists Yeon Seok Kim and Rick Davis, and is described in a paper recently published in the journal Thin Solid Films.