Fiber material

Rewriting the History of Carbon K Fiber Fabrication with Carbon Nanotubes

Schematic of structural changes of carbon nanotubes at different annealing temperatures. Credit: Korea Institute of Science and Technology

A space elevator, a structure connecting the surface of the Earth to a space station, would allow the economical transport of people and materials. However, a very light but strong material is essential to make such technology a reality. Carbon nanotube is a new type of material that is 100 times stronger than steel, but four times lighter, with high copper-like electrical conductivity and diamond-like thermal conductivity. However, previous carbon nanotube fibers were not ideal for intensive use, due to the small contact area with adjacent carbon nanotubes and the limited length they possessed.

A research team led by Dr. Bon-Cheol Ku from the Korea Institute of Science and Technology (KIST) at the Jeonbuk Institute of Advanced Composite Materials in South Korea announced that they had developed an ultra-high carbon nanotube. high strength and ultra high modulus. fibrous material as part of a joint research project with the research team of Prof. Seongwoo Ryu from Suwon University in South Korea and Dr. Juan José Vilatela from IMDEA Materials Institute in Spain. Their research is published in Scientists progress.

Existing polyacrylonitrile (PAN) carbon fibers have high strength and low modulus, while pitch carbon fibers have low strength and high modulus. Previous studies on simultaneously improving the tensile strength and modulus of carbon fibers focused only on adding a small amount of carbon nanotubes. However, the joint research team from KIST, Suwon University and IMDEA produced fibers made entirely of carbon nanotubes without using the conventional carbon fiber precursors, polymer and pitch.

The team fabricated high-density, high-alignment carbon nanotube fibers through a wet-spin fabrication process suitable for mass production, then annealed them at high temperatures to allow their structures to be converted in various specific types, including graphite. As a result, the contact surfaces of carbon nanotubes increased. These carbon nanotube fibers produced in this way are expected to have various applications, as they simultaneously exhibit characteristics of ultra-high strength (6.57 GPa) and ultra-high modulus (629 GPa), which could not be achieved with conventional carbon fibers. The fibers also showed high knot strength, indicating flexibility.

Dr. Bon-Cheol Ku said: “K-carbon fiber manufacturing technology using carbon nanotube materials is what will enable South Korea, a latecomer to carbon fiber, to lead the industry. This important technology will serve as a future engine of growth for the aerospace and defense industries that are needed to propel South Korea into the realm of hardware superpowers.”

“We have secured the original ultra-high-strength, ultra-high-modulus carbon nanotube carbon fiber manufacturing technology, but in order for the mass production of ultra-high-performance carbon fibers to be possible, the mass production of double-walled carbon nanotubes, a basic material, must happen first,” he continued, stating that national-level support as well as industry interest is needed to continue progress.

Molecular agitation has implications for carbon nanotube fibers

More information:
Dongju Lee et al, Ultra-high strength, modulus and conductivity of graphitic fibers by macromolecular coalescence, Scientists progress (2022). DOI: 10.1126/sciadv.abn0939

Provided by the National Science and Technology Research Council

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