Carbon nanofibers in PU foams can tame flammability by 35%

15-Dec-08

Researchers at America's National Institute of Standards and Technology (NIST) have determined that adding a small amount of carbon nanofibers to polyurethane foams used in some upholstered furniture can reduce flammability by about 35% when compared to foam infused with conventional fire retardants. The researchers have been seeking alternatives to nanoclays (found about 10 years ago as effective flame retardant additive) as these do not prevent the melting and dripping of polyurethane foam when exposed to a fire. This molten foam accelerates the burning rate by as much as 300%. The regulatory framework calls for mattresses and upholstered furniture sold in California and used in public spaces be treated with fire retardants to minimize fire risks and injuries. NIST fire researchers have before used upholstered furniture to study its flammability, but in this study, they developed a small-scale technique for evaluating the effect of dripping and pooling on foam flammability. About the size of a slice of toast, the foam samples were treated with one of six combinations of carbon nanofibers or conventional clay flame retardants. The foam "toast" was suspended vertically over a pan, ignited, and the amount of drip was measured. The researchers found that the foam with carbon nanofibers did not drip. NIST fire scientists will continue to study the mechanisms that reduce flammability and dripping and work with entire supply chain to test new blends of foam and carbon nanofibers to improve flame retardant material. Further, plans are in the pipeline to develop sustainable, green fire retardants using cellulosic nanofibers and testing other innovative fire retardant approaches.