Home > Press > Novel Clay-based Coating May Point the Way to New Generation of Green Flame Retardants
 |
Using a testing device called a cone calorimeter, NIST researchers measure the heat-release rate and other flammability properties of materials. Above, untreated polyurethane foam 'catches fire' from a nearby heat source. Below, foam treated with a novel clay-filled coating did not ignite when exposed to the same heat source. Instead, a fast-growing protective layer called char forms on the surface.
Credit: NIST |
Abstract:
In searching for better flame retardants for home furnishings—a large source of fuel in house fires—National Institute of Standards and Technology (NIST) researchers defied the conventional wisdom and literally hit a wall, one made of clay.
Novel Clay-based Coating May Point the Way to New Generation of Green Flame Retardants
Gaithersburg, MD | Posted on June 28th, 2012
It wasn't a dead end, but rather a surprising result that may lead to a new generation of nonhalogenated, sustainable flame retardant technology for polyurethane foam. The thick, fast-forming coating that the NIST team created has a uniformly high concentration of flame-inhibiting clay particles, and it adheres strongly to the Swiss cheese-like surface of polyurethane foam, which is used in furniture cushions, carpet padding, children's car seats, and other items.
"In effect, we can build the equivalent of a flame-retarding clay wall on the foam in a way that has no adverse impact on the foam manufacturing process," explains NIST fire researcher Rick Davis. "Our clay-based coatings perform at least as well as commercial retardant approaches, and we think there's room for improvement. We hope this new approach provides industry with practical alternative flame retardants."
Davis and his NIST colleagues describe the new coating and the process they used to make it in the journal ACS Macro Letters.*
To date, researchers have built up coatings by stacking thin layers in pairs that are held together by basic electrical attraction. With no clay present, just a pure polymer, a thick coating is formed rapidly, but it isn't a fire retardant. With clay in every other layer, either the coating is too thin or the clay content is too low to be an effective fire retardant.
The NIST team tried something you would expect not to work: trilayers consisting of a positively charged bottom topped by two negatively charged layers. Under most circumstances, the two negative layers would repulse each other, but it turns out that hydrogen bonds formed between the two negative layers and overcame this repulsive force.
The resulting trilayer yields a unique result: a thick, fast-forming, and high concentration clay coating on polyurethane foam. This nanocomposite coating is 10 times thicker, contains 6 times more clay, and achieves this using at least 5 times fewer total layers than the traditional bilayer coatings.
"The eight trilayer system thoroughly coated all internal and external surfaces of the porous polyurethane foam, creating a clay brick wall barrier that reduced foam flammability by as much as 17 percent of the peak heat release rate," the team reported. Only a few hundred nanometers thick, the final coating is transparent and the foam still has the same softness, support and feel.
Compared with amounts of current flame retardant applied to polyurethane foam, only half as much of the new clay-based coating was required to achieve comparable levels of performance.
* Y.S. Kim, R. Harris and R. Davis. Innovative approach to rapid growth of highly clay-filled coatings on porous polyurethane foam. ACS Macro Letters, 2012, 1, 820−824. .dx.doi.org/10.1021/mz300102h
####
About National Institute of Standards and Technology (NIST)
The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce.
For more information, please click here
Contacts:
Mark Bello
301-975-3776
Copyright © National Institute of Standards and Technology (NIST)
If you have a comment, please
Contact us.
Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Bookmark:
News and information
Glowing Plant Releases Maker Kit, Enabling Anyone to Make a Glowing Plant at Home: Glowing Plant seeks funds via crowdfunding and raises almost $400,000 May 23rd, 2013
IDTechEx launches online Market Intelligence Portal May 23rd, 2013
UofL scientists uncover how grapefruits provide a secret weapon in medical drug delivery May 22nd, 2013
Atomic-Scale Investigations Solve Key Puzzle of LED Efficiency: MIT and Brookhaven Lab scientists use electron microscopy imaging techniques to settle a solid-state controversy and raise new experimental possibilities May 22nd, 2013
Laboratories
Whirlpools on the Nanoscale Could Multiply Magnetic Memory: At the Advanced Light Source, Berkeley Lab scientists join an international team to control spin orientation in magnetic nanodisks May 22nd, 2013
Atomic-Scale Investigations Solve Key Puzzle of LED Efficiency: MIT and Brookhaven Lab scientists use electron microscopy imaging techniques to settle a solid-state controversy and raise new experimental possibilities May 22nd, 2013
Govt.-Legislation/Regulation/Funding/Policy
Weird science: Crystals melt when they're cooled May 22nd, 2013
Whirlpools on the Nanoscale Could Multiply Magnetic Memory: At the Advanced Light Source, Berkeley Lab scientists join an international team to control spin orientation in magnetic nanodisks May 22nd, 2013
Atomic-Scale Investigations Solve Key Puzzle of LED Efficiency: MIT and Brookhaven Lab scientists use electron microscopy imaging techniques to settle a solid-state controversy and raise new experimental possibilities May 22nd, 2013
Single-Cell Transfection Tool Enables Added Control for Biological Studies: McCormick researchers develop method of delivering molecules into targeted cells May 22nd, 2013
Discoveries
Whirlpools on the Nanoscale Could Multiply Magnetic Memory: At the Advanced Light Source, Berkeley Lab scientists join an international team to control spin orientation in magnetic nanodisks May 22nd, 2013
Bacterial spare parts filter antibiotic residue from groundwater May 22nd, 2013
UofL scientists uncover how grapefruits provide a secret weapon in medical drug delivery May 22nd, 2013
Atomic-Scale Investigations Solve Key Puzzle of LED Efficiency: MIT and Brookhaven Lab scientists use electron microscopy imaging techniques to settle a solid-state controversy and raise new experimental possibilities May 22nd, 2013
Announcements
Glowing Plant Releases Maker Kit, Enabling Anyone to Make a Glowing Plant at Home: Glowing Plant seeks funds via crowdfunding and raises almost $400,000 May 23rd, 2013
IDTechEx launches online Market Intelligence Portal May 23rd, 2013
UofL scientists uncover how grapefruits provide a secret weapon in medical drug delivery May 22nd, 2013
Atomic-Scale Investigations Solve Key Puzzle of LED Efficiency: MIT and Brookhaven Lab scientists use electron microscopy imaging techniques to settle a solid-state controversy and raise new experimental possibilities May 22nd, 2013
Home
Industrial Nanotech Launches Nansulate(R) Vinyl Fresh: Clear Liquid Thermal Insulation and UV Protection Coating Rejuvenates Vinyl Siding on Homes April 18th, 2013
New type of solar structure cools buildings in full sunlight March 27th, 2013
Harris & Harris Group Notes Solazyme and Mitsui Multi-Year Agreement February 7th, 2013
Rolith and AGC Announce Partnership to Bring Anti-Reflective Glass to Market: Agreement with one of the world’s largest glass companies to develop anti-reflective glass technology January 22nd, 2013