by Brianna Crandall — May 8, 2015—In its search for safer, “greener” flame retardants for furniture padding, National Institute of Standards and Technology (NIST) researchers have devised several new and promising biobased fire-resistant coatings from common grocery store ingredients that can be made in one straightforward step.
As reported in a new article, “One-Pot, Bioinspired Coatings To Reduce the Flammability of Flexible Polyurethane Foams,” the NIST team prepared nine water-based mixtures made up of various combinations of potato starch, seaweed gel (agar), laundry booster, clay and similar everyday compounds.
In laboratory tests, six of these “bioinspired” coatings reduced the peak heat release rate—a key measure of flammability—of polyurethane foam by at least 63 percent, compared with untreated foam.
The team subjected the top-performing mixture—starch and a boron-containing compound used in deodorant and other products—to a full-scale fire test that entails igniting the seat cushions of entire chairs padded with treated or untreated polyurethane foam.
The untreated chair, upholstered with a synthetic fabric, was completely engulfed in flames 90 seconds after ignition and was completely consumed in less than two minutes. A melt pool continued to burn after the cushion was consumed by fire.
In contrast, the fire in the chair treated with the NIST-devised coating remained confined to the cushion 90 seconds after ignition, even though the fabric covering had burned completely. The researchers recorded a 71 percent drop in the total amount of heat released, so that combustion could not be sustained and the flames did not spread, points out NIST.
Furniture fires are the leading cause of casualties in residential fires. In 2013, they accounted for about 30 percent of more than 2,700 deaths in residential fires, according to the National Fire Protection Association. Fires that start in furniture, such as those lit by a burning cigarette or a nearby heater, account for the largest share, but furniture also serves as a major fuel source for fires that originate elsewhere, notes NIST.
“The results of the full-scale fire tests are very encouraging,” says NIST team leader Rick Davis. “The performance of our coating suggests that fire can be contained to burning furniture so that it does not spread, intensify to the point of flashover, and increase the risk of injury or death.”
The quick, uncomplicated process used by NIST researchers could lend itself to industry adoption. However, additional research is necessary to determine the durability of the new coatings and to assess other properties affecting performance and manufacturing applications.
In addition to furniture, chemical flame retardants are used in a variety of other consumer products. Several have been banned, and some others have been linked to human health risks and environmental problems. NIST’s bio-inspired, experimental coatings are contributing to the search for alternatives.
Video clips of the NIST burn tests for the standard upholstered chair and the treated upholstered chair may be viewed online.
