Cotton, clay make hot pair

Agricultural Research Service scientists have merged two natural products, each with unique qualities, to create a brand-new material that offers both heat tolerance and toughness.

Chemist Leslie A. White and mechanical engineer Christopher D. Delhom have accomplished this by joining cotton fibers with particles of clay. The resultant material — boasting cotton's softness and clay's durability — could someday be used as fabric for protective apparel and as insulation that protects against fire in homes.

Readily available in a pure and usable form, clay minerals can enhance the flame-retardant properties of a textile. They also give it strength. Scientists have known this for some time, but they've never before tried pairing clay with a plant material, such as cotton.

Compared to unbleached cotton, the combination cotton-and-clay product has an increased heat tolerance of 70-85 degrees.

White, who's located in the ARS Cotton Textile Chemistry Research Unit of the Southern Regional Research Center in New Orleans, La., was able to create the novel fibers by dissolving cotton fibers with a solvent and then mixing in clay particles on a molecular level.

Montmorillonite clay particles, the same type used in some cat litters, are incorporated into the cotton fibers as microscopic-sized particles.

Once the mixture is dried and the solvent removed, the tiny clay particles become dispersed and embedded throughout the cotton matrix.

Not only is this cotton-clay “nanocomposite” natural, but the process by which the two components are joined is considered environmentally friendly. The solvent used to dissolve the cotton fibers is recyclable and is applied in a closed system.

White and Delhom are investigating a range of cellulosic fibers, including those of wood, grass, leaves and even recycled newspaper, to see if they can be beneficially transformed with the addition of different types of clay.

Read more about the research in the April issue of Agricultural Research magazine, available online at:

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