Carbon Nanofibers Aid Foams' Fire Resistance
Adding a small amount of carbon nanofibers to the polyurethane foams used in some upholstered furniture can reduce their flammability by about 35 percent more than conventional fire retardants, researchers from the Commerce Department's National Institute of Standards and Technology have shown. Mattresses and upholstered furniture sold in California and used in public spaces such as hotels and offices must be treated with fire retardants or barrier fabrics, and this research could lower the fire danger further.
NIST scientists have known for 10 years that nanoclays are effective fire retardant additives, but they've looked for alternatives because nanoclay flame retardants don't prevent polyurethane from melting and dripping when exposed to a fire, which can increase its burning rate by up to 300 percent, the agency reported Dec. 12. "It also creates so much smoke that it is a life safety hazard," said Jeff Gilman, leader of the Materials Flammability Group in the Building and Fire Research Laboratory. In the latest research, the addition of carbon nanofibers to foam samples about as large as a slice of toast was made because the scientists knew adding nanoparticles to a polymer normally increases the viscosity so it doesn't flow as readily.
"These small-scale experiments correlate well with the fire behavior of larger foam samples and are easier and less expensive to conduct," said Gilman. "The small-scale tests will allow us to cost-effectively perform more experiments and help us find an optimal fire retardant faster. Carbon nanofibers are still more expensive than conventional flame retardant materials, but because the price is decreasing and so little needs to be used, they could soon be an affordable and effective option," he said.