Materials take wing: what to do with 4 billion pounds of feathers? - research on turning feathers into useful products

Science News,  Feb 23, 2002  by Jessica Gorman

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In July 1999, textile engineer Brian George of Philadelphia University's School of Textiles and Materials Technology visited a friend who raises chickens. After helping with the slaughter, George suddenly realized that he and his friend had a lot of feathers on their hands--and nothing much to do with them. "It seemed like a waste," he recalls.

In fact, George discovered, his friend's chicken farm is only a small part of a much larger problem. The poultry industry in the United States alone produces 2 to 4 billion pounds of feathers each year. Chicken- and turkey-processing companies have two main options: They can either sell the feathers for a low price to producers of poultry and cattle feed or pay to send them to landfills.

George wondered what else might be done. He quickly found that other researchers had been thinking about the same thing. Just a couple of days after his trip to the chicken farm, the Philadelphia scientist listened to a Department of Agriculture researcher talk at a scientific meeting. Walter F. Schmidt spoke about the potential of transforming components of feathers into useful products. The challenge is separating a feather's quill--the shaft--from its barbs, the fibers extending from the quill.

Feathers' quills and fibers are both made of the protein keratin, the stuff of hair, nails, and wool. But the quill is hard and has a disorganized microscopic structure, while the fibers are soft and posses a very orderly microstructure. Even finely chopped mixtures of whole feathers contain annoying chunks of quill, so they're difficult to work into products such as paper, cloth, or insulation.

Hungry farm animals don't seem to mind the grit, but the global market for raw animal byproducts as feed has been decreasing. Scientists suspect that mad cow disease spread when farmers fed infected animal byproducts to cattle.

Any solution to the feather problem demands a convenient way to separate quills and fibers. Schmidt and his colleagues at the United States Department of Agriculture's Agricultural Research Service in Beltsville, Md., recently developed an instrument for stripping a feather's quill of its fibrous barbs. It's a contraption much like a paper shredder but a "high-precision shredder," says Schmidt. Now, with pilot plants starting to use this technology to produce pure fibers and pure quill material, researchers have begun looking for novel uses for the fowl product.

FEATHER SHREDDER AND BEYOND The USDA instrument lines up feathers and cuts them parallel to the quills, stripping the fibers off essentially undamaged. Then, to separate the light fibers from the heavier quills, the researchers put the mixture through a turbulent airflow. The fibers float up, and the quills drop down.

Before the shredding begins, the USDA technique sanitizes the feathers, which can arrive from processing plants coated in poultry saliva, oils, and dirt. The cleaning solution--70 percent ethanol in water--sterilizes the feathers, says Schmidt. You get pristine, clean feathers coming out," he says.

According to Schmidt, the alcohol solution has benefits over other cleaners. The solution isn't hazardous, and less water is required to rinse alcohol off the feathers than to remove detergent. Also, the ethanol can be distilled and reused.

Three companies--Featherfiber Corp. of Nixa, Mo., Maxim of Pasadena, Calif., and Tyson Foods, of Springdale, Ark.--have licensed the new technology from the USDA and are already sending samples of their products to materials scientists around the world.

In some of their first experiments with feathers, George and his students twisted 1-to-2-inch-long turkey-feather fibers with nylon to make yarns, which they knitted into fabrics. In strength tests, the yarn was weaker than pure nylon, but the fabrics insulated better than nylon cloth, says George. Such turkey-based fabric might provide insulation in jackets or sleeping bags, he says. He reported some of that work last November in Boston at the fall meeting of the Materials Research Society.

Now, George's team is transforming turkey-feather fibers into nonwoven, degradable mats for erosion control in construction sites and other locations. The researchers use a common textile instrument that blows the feather material into a fragile, half-inch-thick mat that's loosely held together by friction between the fibers. Then, the scientists strengthen each 36-by-20-inch mat by spraying biodegradable latex on each side.

George and his colleagues are testing the mats on the university campus to see how long they take to degrade and what effect they have on soil. Although the feathers have been sanitized, George wants to be sure there are no lingering microorganisms on the feathers that might leach into the ground.

Also, he suspects that the feather protein might enrich the soil and boost the growth of vegetation that holds soil in place. Currently, erosion-prevention mats are made from more expensive, woven coconut fibers or from wood chips held together with nylon webbing, he says.