Fully recyclable carbon nanotube fibers have far-reaching implications for all sectors of manufacturing

In an important step toward building a sustainable, circular economy, Rice University researchers have published research in Carbon magazine that demonstrates that carbon nanotube (CNT) fibers can be fully recycled without losing their structure or properties. It was announced on . This discovery positions CNT fibers as a sustainable alternative to traditional materials such as metals, polymers, and larger carbon fibers, which are notoriously difficult to recycle.

“Recycling has long been a challenge in the materials industry. Recycling metals is often inefficient and energy-intensive, polymers tend to lose their properties after reprocessing, and carbon fibers cannot be recycled at all. We just have to chop it up and downcycle it,” said corresponding author Matteo Pasquali, director of Rice’s Carbon Hub and the AJ Hartsuk Professor of Chemical and Biomolecular Engineering, Materials Science, and Nanoengineering and Chemistry.

“As CNT fibers are scaled up, we can recycle these new materials in the future to proactively avoid the waste management issues that arise as other engineered materials are used on a large scale. “We expected that recycling would be difficult.” Surprisingly, carbon nanotube fibers far exceed the recyclability of existing man-made materials. It turned out to be a solution to environmental problems. ”

The research team used solution-spun CNT fibers made by dissolving commercial fiber-grade CNTs in chlorosulfonic acid, a widely used industrial solvent. Since post-consumer recycling always brings together materials produced by different companies using different processes, it was important to assess the impact of multiple material sources on the fiber production process and fiber properties.

Fibers made from different types of CNTs produced by different manufacturers were first processed into separate single-source virgin fibers and then recycled by combining them and mixing them with chlorosulfonic acid. Ta. Surprisingly, when the two fibers were mixed, they completely redissolved and there was no sign of separation of the two raw materials into different liquid phases. This remelted material was spun into mixed-source recycled fibers that retained the same structure and alignment as the virgin fibers.

“By using two different sources of carbon nanotubes, we ensured that the recycling process reflected real-world conditions,” said co-lead author Michelle Duran Chavez, a graduate student in chemistry. I am. “Surprisingly, the regenerated fibers showed comparable mechanical strength, electrical conductivity, thermal conductivity, and alignment, which is unprecedented in the field of engineering materials.”

This study revealed several important findings that position CNT fibers as a promising material in efforts towards sustainable practices. The most important of these is the complete recyclability of CNT fibers. Unlike traditional materials, especially polymers and carbon fibers, which degrade during recycling, CNT fibers retain 100% of their original properties after recycling.

“Maintaining this quality means that CNT fibers can be used and reused in demanding applications without compromising performance, resulting in extended lifecycles and reduced need for new raw materials.” said author Ivan R. Siqueira, a recent Rice University doctoral graduate. He is affiliated with the Department of Chemical and Biomolecular Engineering and is currently an associate professor of mechanical engineering at the Pontifical University of Rio de Janeiro.

Equally important is the efficiency of the recycling process. Researchers have demonstrated that recycling CNT fibers is significantly more efficient than traditional recycling methods for metals and polymers, which often involve high energy use, hazardous chemicals, and labor-intensive sorting. .

However, CNT fibers can be recycled without separation, as fibers from different sources can be combined to produce high-quality recycled materials. Once these materials reach scale, this simple recycling process significantly reduces waste, energy consumption, and carbon emissions associated with manufacturing the materials.

“Being able to fully recycle CNT fibers has far-reaching implications for industries such as aerospace, automotive and electronics,” Duran Chavez said. “We hope this will pave the way for fully recyclable composite materials in aircraft, vehicles, social infrastructure and more, ultimately reducing environmental impact across a wide range of sectors.”

Other co-authors on the paper include Oliver Dewey, a Rice University graduate now at DexMat; Stephen Williams. Cedric Ginestra, currently playing for LyondellBasell. Yinglu Song is currently a postdoctoral researcher at Purdue University. Juan de la Garza, a graduate of Rice University; Currently affiliated with Axiom Space. and Jeff Wehmeyer, assistant professor of mechanical engineering.