The project, “Flame retardant and damage-resistant nanocoatings for fabric, fibers and fill from environmentally benign materials,” will extend the Grunlan team’s research into improving the antiflammable behavior of foam (mostly used for furniture padding and insulation) and fabric (primarily for clothing).
Grunlan is also a faculty member in the Materials Science and Engineering Program.
In fabric, the flame-resistant polymer coating involves covering every microscopic fiber in a fabric with a thin composite coating of polymer and clay to enhance the flame-retardant properties of the fabric. (left, a fabric burn test)
The thin films are about one-tenth of a micron thick, or about one-thousandth the thickness of a human hair, and are created with the layer-by- layer assembly technique in which the coating is deposited onto the surface of the fiber being coated. The coating is so thin that it adds only 1 to 2 weight-percent to the fabric and does not negatively alter the fabric's color, texture or strength.
And in foams, the nanocomposite clay-polymer mixture coats the interior walls of the foam. The result is that when burned, the treated foam keeps its shape instead of puddling at high temperatures like untreated polyurethane foam does. This quality eliminates the melt-dripping effect that further spreads fires. (right, treated foam after a burn test)
Grunlan says in fabrics, though, the results were disappointing, so the team turned to materials that produce a protective carbon foam coating when exposed to high temperatures (called intumescence). Grunlan said he was inspired by the intumescent coatings used in the construction industry on steel girders to protect a skyscraper’s skeleton. Grunlan’s group scaled the technology down to the nanometer level and published their findings in the Sept. 8 issue of Advanced Materials .
The research team’s most recent work has been featured in Nature, Chemical & Engineering News, Science News, Science News for Kids, and on the local CBS affiliate in Denver, where Grunlan presented his work at a meeting of the American Chemical Society.