Plasma, Nanotechnology Used To Upgrade Cotton Fabric Qualities (7/22/2007)

Just as you juggle a mix of multitasking chores in this time-starved world, core products to Texas' agricultural economy - such as cotton - are on the clock to provide more new and interesting features before you and other consumers head on down the shopping highway.

"The only way for us to keep our market or really ever grow in the future is to add value to regular, plain cotton fabric," said Eric Hequet, an expert in fiber properties at Texas Tech University's International Textile Center.

Lately here in the heart of cotton country, Texas Tech researchers have focused on cotton fabric functionalization by adding multiple features such as wrinkle and stain resistance, along with antibacterial, ultraviolet radiation protection and even self-cleaning capabilities - all in a single manufacturing processing step.

Two application techniques - plasma technology and sol-gel nanotechnology - both show promise. The research is supported through grants from the Texas Department of Agriculture's Food and Fiber Research Grant Program.

"Today, you can easily find wrinkle-free and stain-repellant pants that were made through a wet chemistry process," Hequet said. "But when you touch them, it doesn't feel like cotton.

"We needed to find a way to keep the feel of cotton against the skin, but impart the important functional properties like wrinkle free, antibacterial, UV protection," he said. "The obvious solution was to treat only one side."

The answer came from the high-tech world of semiconductors where plasma technology has been used for years as a cleaning method.

In the case of cotton, a piece of cotton fabric was placed in a plasma chamber at Texas Tech's International Textile Center where, microwave plasma treatments were applied to one side of a lightweight cotton fabric with oxygen, nitrogen and argon gas at various microwave power levels and exposure times.

Technically, the plasma treatment of cotton fibers creates radicals on the surface of the fabric that are used to initiate polymerization reactions.

The plasma experiments started almost five years ago with small-scale laboratory experiments using a plasma chamber that was 25-by-25 inches. Now, there are room-size, commercial-size plasma chambers available in Europe capable of processing entire rolls of fabric.

"We did the fundamental work to prove the concept," said Noureddine Abidi, a polymer chemist at the International Textile Center.

Meanwhile, sol-gel technology, which uses a more traditional wet chemistry process that takes advantage of nanoparticles, is about two years into development. "We've also proved this concept," Abidi said. "Now, we have to see if we can scale the process up to commercial work levels."

The sol-gel process has been in use for years to make high purity glasses and ceramics. Now, the Texas Tech researchers are adapting the technology to cotton fabric.

"By taking advantage of the progress in nanotechnology, the functionality of cotton fabrics may be greatly expanded," he said.

For instance, in one single sol-gel treatment the researchers can produce a fabric that has antibacterial, wrinkle free, and water repellant features, in addition to UV protection and self-cleaning properties.

"Our goal is always the same," said Dean Ethridge, managing director of the International Textile Center. "We are searching for new ways to increase the use of cotton. Regular untreated cotton is a good product, but it's not a perfect product. There are plenty of new functions that consumers would like to have."

Note: This story has been adapted from a news release issued by Texas Tech University

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