White cotton can usually only be made flame-retardant by adding toxic flame-retardants, but a new form may make it possible to make cotton fabrics that are inherently non-flammable.
technology
January 18, 2023
Flame-resistant cotton was created by crossing parent strains with dissimilar properties. This allows us to create a fire resistant fabric without adding toxic chemicals.
When fire spreads into people’s homes, it often ignites the fibers. As such, many countries require a certain level of resistance in fabrics used in furniture. Some workers and soldiers are required to wear flame retardant clothing. There are synthetic fibers that are inherently flame retardant, such as aramid, but they are not as comfortable or popular as natural fibers such as cotton.
Some varieties of brown cotton have some degree of fire resistance, but currently the only way to make white cotton fire resistant is to add flame retardant chemicals. It releases toxic substances such as formaldehyde, and cleaning the fabric can also cause it to lose its fire resistance.
Previous research on brown cotton varieties suggests flame retardancy due to the presence of a class of colorless compounds known as flavonoids, suggesting that it can also occur in white cotton. Gregory Thyssen of the United States Department of Agriculture Agricultural Research Service (USDA-ARS) and his colleagues looked for flame retardancy in hundreds of white cotton lines previously created by USDA-ARS to develop improved varieties. I made it also had this feature.
Standard untreated cotton is consumed by flames in seconds (top row), while new fire resistant cotton extinguishes (bottom row). Thyssen et al., 2023, PLOS ONE, CC0
These strains were created from 11 diverse parental strains using breeding techniques designed to produce high diversity in the offspring.
The researchers burned a small amount of each cotton strain and chose the five that produced the least amount of heat when burned. A nonwoven fabric was then made from these five lines and subjected to a standard flammability test by placing the strip of fabric on a 45 degree incline and exposing it to a flame for a few seconds (see video above). After the flames were removed, four of the five fabrics self-extinguished, while the regular cotton strips burned out completely.
“Fiber quality was unaffected by the new self-extinguishing properties,” says Thyssen. “These new strains are developed from white cotton varieties that are already in production and therefore have desirable traits for producers and consumers.”
Thyssen and his colleagues were surprised to find this level of flame retardancy, given that none of the 11 parental strains possessed this property. Although they have identified several genetic variants, they have not yet been able to pinpoint the specific compounds involved.
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