Futuristic Fibers

Whether it's making carpet from plastic bottles or protective gear from high strength polymers, science allows North Carolina’s traditional textile industry to create new fibers to meet high tech needs.

MCADENVILLE — “The carpeting you walked on as you entered this office started from this,” says Russ Dirks, the Director of Fiber Extrusion for the carpet division of Pharr Yarns. Dirks unscrews the cap from a mason jar and pours tiny white pellets from the jar onto a large conference table. The pile of pellets looks like a bunch of aspirin, but far from it.

The pellets are called PET (polyethylene terephthalate) pellets. Made from several organic compounds mixed with chemical catalysts, chemically it’s a fully cross-linked polymer. But depending how it is processed, it can be made into thousands of products from clear plastic soft drink bottles to the clear packaging used in grocery stores. The average person probably knows its more common name — polyester.

It turns out, this type of plastic is also easily recycled. Those same properties that allow polyester molecules to be shaped into bottles and food containers allow Pharr Yarns to stretch it into thin carpet fibers. That’s right, you might be walking on the plastic bottle you drank from just a few months ago.

The stretching process is called extrusion. It’s all based on chemistry and it begins about three stories above the Pharr Yearns conference room, in a cavernous factory. Giant hoses run down from the top of a machine into huge bags of pellets on the floor. In a weird way it looks like the machine is drinking through a straw.

Inside the system, the pellets are dried and melted at about 300 degrees Celsius. That’s about 570 degrees Fahrenheit. The semi-molten fiber is then drawn through a spinneret. The series of spinning wheels that pull the yarn in and out of the machine shape the fiber and also stretch it.

“What chemists found years ago is that with polyester, if you stretched it the fibers got stronger,” explains Dirks. “The long chain molecules that this vessel creates allow you to stretch the fiber so that all of the molecules interlace themselves and that gives you a long, strong fiber.”

Dirks opens a door on the side of the gigantic machine to show the thin, glittering, just-created fibers being pulled through the device. When asked what it was about polyester that made it so popular, Dirks explains that it was the combination of costs and capability that drew the attention of chemists.

“Nylon was expensive, polypropylene was cheap, polyester was in the middle but it has great properties for carpet and it’s great for textiles,” Dirks says, tugging at his t-shirt to make a point. “If you look at a t-shirt, it’s a 50-50 blend and that’s because polyester is synthetic and cotton is natural. Cotton has wicking capabilities and polyester doesn’t like water so it wicks on its own.” 

Ironically for all of the machinery that towers above the factory floor, transforming PET pellets into carpet fiber only takes about seven minutes. But the heat and chemical properties of the molecules allow the material to be made thinner and thinner as it goes through the process.

The wheels on the extrusion machines have the fiber moving at 120 miles per hour as it is wound. It takes about 200 filaments to create a fiber bundle, so the goal of the process is to have about 20 miles of finished fiber stretched out to 20% of the width of a human hair.

And if that’s not enough of a wow factor, a photo cross-section of the fiber that is magnified about 800 times shows the fiber is also shaped into what appears to be an addition sign. It’s the shape that makes the carpet soft.

“If you have a yarn system made out of different shapes and wrinkles with corners on edges, then you have the ability to put air in between the filaments,” says Dirks, handling a newly made bundle of carpet fibers. “So if you feel a carpet that has that springy buoyancy, it’s because we’ve textured the yarn, which really makes the yarn bigger than it’s supposed to be.”

You don’t think about carpet and science, but the work that is happening at Pharr Yarns is all based on chemistry and the particular features the chemical properties give to each type of fiber.

“We’re yarn spinners and the science in all of this is that we want to know the different fibers and the efficacy of the fibers, and their value in protection or performance,” explains Michael Strader, New Business Innovation Manager at Pharr Yarns, as he walks through the production floor. It is noisy and there are long rows of machines spinning fibers that seem to stretch forever. 

“Of course once we know all of the properties of the fibers, we have to know how to blend them,” Strader adds.

He points out what looks to be a bale of cotton.

“This material is made from regenerated cellulose, which you might remember from biology is part of what forms the cell wall in plants,” he says as he pulls out a hunk of snow white and soft fibers. “But in this case, it is made from the bark of birch trees. It’s very fire resistant.”

Nearby is a similar looking bale, but Strader says that one is made from the same material as PVC piping. There are coils of blue fiber not far away, which is traditional nylon. But when it is combined with other materials it produces fiber that is cut resistant.

Pharr Yarns produces about 150 types of fibers. Over the years, Pharr Yarns has morphed from being just a true synthetic, polyester, or commodity type producer of yarns to high performance materials. Today, Pharr Yarns produces about 150 types of fibers.

“There is no one fiber that solves every problem, so you take the best properties of different fibers and blend them,” says Strader. “Today our science is about protecting people and protecting products, and we are proud to say that includes making the fibers that are used in garments that soldiers and airmen and women wear in dangerous situations.”

You could say the properties of some of the fibers are out of this world. It turns out that would be true. Pharr Yarns makes some products that are orbiting the earth.

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