Novel coatings show great promise as flame retardants in polyurethane foam

Aug 03, 2011

Gram for gram, novel carbon nanofiber-filled coatings devised by researchers from the National Institute of Standards and Technology (NIST) and Texas A&M University outperformed conventional flame retardants used in the polyurethane foam of upholstered furniture and mattresses by at least 160 percent and perhaps by as much as 1,130 percent.

The impressive test results, reported in the journal Polymer, suggest that significant fire-safety advantages can be gained by coating polyurethane foam (PUF) with a club-sandwich-like arrangement of thin layers containing carbon nanofibers and polymers. The upshot, says NIST researcher Rick Davis, is that the experimental coating seems to create the equivalent of a "fire-resistant armor" on the porous foam.

Ignition of soft furnishings account for about 5 percent of residential fires, and the consequences are disproportionately high. These fires are responsible for a third of fire-caused deaths of civilians and 11 percent of property losses due to fires in homes.

The flammability of mattresses is regulated by federal law. A complementary rule to regulate the flammability of upholstered furniture has been proposed recently.

Several organizations, however, have challenged the health and safety of some flame retardants designed to protect against soft furnishing fires. And, a bill pending in California would ban the use of certain halogenated flame retardants in that state.

Today, recipes for making PUFs result in foams in which fire retardants are embedded in the interior. In contrast, the experimental technology uses the carbon nanofiber fire retardant as a coating that covers all the nooks and crannies on the sponge-like PUF surface. The new approach, says Davis, should be attractive to PUF manufacturers because the surface treatment has the potential to deliver a low flammability PUF without major change to the foam manufacturing process, thus saving time and money.

The NIST-Texas A&M team coated square samples of commercially available PUF with four bilayers of a carbon nanofiber-polymer combination. The average thickness of the coating was about 360 nanometers, increasing the mass of the foam by only 3 percent. By themselves, the carbon nanofibers accounted for 1.6 percent of the foam mass. Since the carbon nanofibers are only in the coating, all the carbon nanofibers are clumped like matted whiskers within the top 360 nanometers of the surface—assembled into the fire-blocking armor.

The team used a standard benchtop fire test to measure the fire performance of coated and uncoated PUF. The carbon nanofiber coatings reduced PUF flammability (measured as the peak heat release rate from an ignited specimen) by 40 percent. That result was more than 3 times better than achieved by putting the same carbon nanofibers in the foam (part of the foam recipe).

When compared at the same concentrations, the carbon nanofiber coating significantly outperforms three classes of commercially available flame retardants commonly used in PUF. Reductions in flammability achieved with the coating, according to the researchers, were 158 percent better than the reduction calculated for nonhalogens, 288 percent better than halogens, and 1,138 percent better than halogen-phosphorous .

Additionally, the experimental "prevents the formation of a melt pool of burning , which in a real fire scenario, may further reduce the resulting fire threat of burning soft furnishings," the authors write.

Explore further: Researchers seek to stimulate skin regeneration in third-degree burns

More information: Polymer Volume 52, Issue 13, 8 June 2011, Pages 2847-2855. doi:10.1016/j.polymer.2011.04.023

Related Stories

Potentially toxic flame retardants detected in baby products

May 18, 2011

Scientists are reporting detection of potentially toxic flame retardants in car seats, bassinet mattresses, nursing pillows, high chairs, strollers, and other products that contain polyurethane foam and are designed for newborns, ...

Study documents PBDE flame retardant levels in children

Apr 15, 2011

(PhysOrg.com) -- A group of 264 Mexican-American children living in California had higher levels of polybrominated diphenyl ether (PBDE) flame retardants in their blood serum than 283 counterparts living in Mexico, according ...

UMass Amherst Scientists Create Fire-Safe Plastic

May 30, 2007

Scientists from the University of Massachusetts Amherst have created a synthetic polymer—a building block of plastics—that doesn’t burn, making it an attractive alternative to traditional plastics, many of which are ...

Recommended for you

Video: This town has been on fire for 50 years

12 hours ago

In 1962, an underground fire started in the coal-mining town of Centralia, Pennsylvania. Fifty-three years later, that fire still burns. In this week's episode of Reactions, we explain the history and science ...

Genetic switch detects TNT

14 hours ago

Cleaning-up post-war explosive chemicals could get cheaper and easier, using a new genetic 'switch' device, being developed by scientists at the University of Exeter to detect damaging contaminants, such ...

Why Matisse's bright yellow pigments fade to beige

14 hours ago

An international team of scientists led by Jennifer Mass, Winterthur Museum's senior scientist and an affiliated University of Delaware faculty member, has announced new findings on why a bright yellow pigment ...

Killer sea snail a target for new drugs

Jul 06, 2015

University of Queensland pain treatment researchers have discovered thousands of new peptide toxins hidden deep within the venom of just one type of Queensland cone snail.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Telekinetic
1 / 5 (1) Aug 03, 2011
What happens to carbon nanofibers after 5 or 10 years when they break down and shoot out of the cushion when you sit down? Why, they lodge in the lungs of the person sitting directly across from you.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.