http://www.digitaljournal.com/science/all-natural-mixture-is-a-promising-fire-retardant/article/385904

All-natural mixture is a promising fire retardant

Posted Jun 7, 2014 by Tim Sandle
A dash of clay, a dab of fiber from crab shells, and a dollop of DNA is not a magic potion but the ingredients of promising green fire retardant.
Two gas cylinders exploded on the balcony of an apartment in Moscow causing a fire.
Two gas cylinders exploded on the balcony of an apartment in Moscow causing a fire.
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The combinations of ingredients are applied to polyurethane foam to create a bio-based coating. The new coating uses negatively charged DNA molecules to link two positively charged materials known to enhance fire resistance: montmorillonite, a type of soft clay that forms tiny crystals, and chitosan, a fiber derived from the shells of shrimp, lobsters and other crustaceans. For its part, DNA, which was obtained from herring sperm, may also confer added protection because it bubbles and swells when heated, protecting the material beneath.
Studies have shown that this coating greatly reduced the flammability of the common furniture padding after it was exposed to an open flame. Peak and average rates of heat release (two key indicators of the magnitude of a fire hazard) were reduced by 48 percent and 77 percent, respectively, according to a report in the journal Green Materials (“DNA-based nanocomposite biocoatings for fire-retarding polyurethane foam”).
The key to the bio-based materials fire resisting ability is that coatings must be applied more generously, in stacks of about 20 layers as compared with six or seven layers. This makes for a very effective fire retardant. A fire retardant is a substance that reduces flammability of fuels or delays their combustion.
The new retardant has been invented by researchers at the National Institute of Standards and Technology (NIST), which is an agency of the U.S. Department of Commerce.