Pavan Manvi holds up a small tube made from white textile, strong and yet elastic. The resistance is so great that he needs both hands to stretch it. “This material has just the right elasticity for a compression stocking,” he says, satisfied. As a researcher from the Institute of Textile Technology at RWTH Aachen University, Manvi knows that a perfect result is by no means a given. That’s because he and his colleagues have adopted an innovative new manufacturing approach: The fibers of the prototype are made partly from a molecule present in the air all around us that is reputed to play a major role in global warming – the greenhouse gas carbon dioxide, or CO₂.

Now CO₂ has turned a researcher’s dream into reality: It can replace a certain amount of crude oil, the scarce resource used predominantly as a raw material by the chemical and plastics industry to date. Both CO₂ and crude oil contain carbon – a valuable element that is required for so many products, including textiles.

Synthetic fibers made from CO₂

Manvi is making the most of this opportunity: He and his colleagues in Aachen, working alongside researchers from the Technical University of Berlin and Covestro, have succeeded in manufacturing market-ready synthetic fibers from CO₂ and incorporating them in articles of clothing.

“We’ve demonstrated that we can produce high-performance fibers from thermoplastic polyurethane on a large scale in our melt spinning facility. This saves on fossil raw materials and reduces our CO₂ footprint compared with conventional synthetic fibers,” says Manvi, who has been pursuing the research project at RWTH for the past three years. “We can also eliminate the solvents commonly used in the process and thus improve our environmental footprint even more.”

We can produce high-performance fibers using CO₂

Pavan Manvi, Institute of Textile Technology, RWTH Aachen University

Saving fossil resources

At the heart of this is a pioneering process developed by Covestro and its partners. For the first time, up to 20 percent of the crude oil commonly used in the manufacture of polyol, a precursor of polyurethanes, can be replaced with CO₂. This is difficult, since carbon dioxide is extremely inert and a great deal of energy is required to produce chemical reactions with it. However, Covestro helped develop a special catalyst that limits the amount of energy needed. “Thanks to this research breakthrough, we can now manufacture polyols based on CO₂ on an industrial scale,” says Dr. Christoph Gürtler, who heads the catalyst research team at Covestro.

The innovative precursor known as cardyon^® was initially devised for use in the flexible polyurethane foam required to make mattresses and upholstered furniture – products with this innovative foam are already available on the market. However, cardyon^® recently also made a name for itself in the world of sports when it was used for the new synthetic surface of a well-known hockey club in Krefeld (see “Fit with CO₂”).

Tested by textile manufacturers

Now the textile industry will become an application area for cardyon^®. Its elastic fibers have already been tested by companies and used in the manufacture of yarns, socks, compression stockings and tapes. Textile manufacturers insist that the new material must be of the same quality in every respect and enable processing just as easily as conventional fibers. “We want to run tests to see how the new technology can be harnessed across various stages of the value chain,” says the chemist Dr. Jochen Norwig, who is responsible for coordinating an EU-funded research project at Covestro that includes the development of the new CO₂ fibers.

And Covestro has its sights on even more application areas. “CO₂ is increasingly becoming an all-purpose raw material,” says catalyst expert Gürtler, whose view coincides with that of other professionals from the worlds of science, politics and society at large (see “Moving away from oil”). “We’re setting our sights on many other applications and sectors besides synthetic fibers and the textile industry. For instance, our researchers are working on the use of carbon dioxide in the production of car seats and in insulating materials for buildings and refrigerators.”

Cross-industry collaboration

Gürtler and his colleagues are particularly fascinated by broad cross-industry approaches such as that of the pan-European research project “Carbon4PUR”. Here, Covestro is heading a team of 14 partners from seven countries who are exploring how to extract the carbon from steel industry emissions, such as CO₂ and carbon monoxide, for use in chemical processes instead of the crude oil used to date. “Ultimately our aim is to incorporate CO₂ in many other types of plastic and to use it to replace as many fossil materials as we can,” says Gürtler. The goal is to deploy carbon as intelligently as possible in order to close the carbon cycle.