National Institute of Standards and Technology (NIST) researchers took a trip to the grocery store and cooked up their best fire-resistant coatings for furniture padding yet. More important, these protective coatings were formulated in a single step, a process far simpler than the time-consuming “layer by layer” process deposition process required of previous “green” flame retardant candidates.
To formulate the fire protective coating, the NIST team prepared nine water-based mixtures composed 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.
Encouraged by the lab results, 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 in which chairs padded with treated or untreated polyurethane foam were ignited.
The upholstered fabric of both chairs was completely engulfed in flames 90 seconds after ignition. In less than two minutes, the upholstery fabric on both chairs was completely consumed. Within six minutes, the untreated padding had burned completely, leaving a burning, melted pool. However, the flames on the chair treated with the NIST-devised coating remained confined to the padding 90 seconds after ignition, although the fabric had burned completely. Combustion could not be sustained and the flames did not spread because the coating produced a 71% drop in the total amount of heat released, the study reported.
Furniture fires are the leading cause of death in house fires. According to the National Fire Protection Association, they accounted for about 30% of more than 2,700 deaths in residential fires in 2013.
"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 study, published in the March 25, 2015 issue of ACS Applied Materials & Interfaces, reported the newest coatings were crafted with what the researchers call a "one-pot" process in which the ingredients were added to water, heated and stirred until the solution became a gel, and then cooled. Depending on the ingredients, preparation times ranged from about 30 minutes to two hours.
The uncomplicated process could lend itself to industry adoption. However, additional research is needed to determine the durability of the new coatings and to assess other properties affecting performance and manufacturing applications.
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