New Nanotube fibers have unmatched combination of strength, conductivity, flexibility

Rice University’s latest nanotechnology breakthrough was more than 10 years in the making, but it still came with a shock. Scientists from Rice, the Dutch firm Teijin Aramid, the U.S. Air Force and Israel’s Technion Institute this week unveiled a new carbon nanotube (CNT) fiber that looks and acts like textile thread and conducts electricity and heat like a metal wire. In this week’s issue of Science, the researchers describe an industrially scalable process for making the threadlike fibers, which outperform commercially available high-performance materials in a number of ways.

“We finally have a nanotube fiber with properties that don’t exist in any other material,” said lead researcher Matteo Pasquali, professor of chemical and biomolecular engineering and chemistry at Rice. “It looks like black cotton thread but behaves like both metal wires and strong carbon fibers.”

“The new CNT fibers have a thermal conductivity approaching that of the best graphite fibers but with 10 times greater electrical conductivity,” said study co-author Marcin Otto, business development manager at Teijin Aramid. “Graphite fibers are also brittle, while the new CNT fibers are as flexible and tough as a textile thread. We expect this combination of properties will lead to new products with unique capabilities for the aerospace, automotive, medical and smart-clothing markets.”

Nanotubes are tightly packed in the new carbon nanotube fibers produced by Rice University and Teijin Aramid. This cross section of a test fiber, which was taken with a scanning electron microscope, shows only a few open gaps inside the fiber.

Science – Strong, Light, Multifunctional Fibers of Carbon Nanotubes with Ultrahigh Conductivity

Technology Review has coverage

The filaments are about 25 micrometers thick and can be woven into thicker threads to hold up heavier loads, or to carry more current. Pasquali says the group can now produce the nanotube materials continuously, and that it takes a couple of hours to produce a few hundred meters.

Rice group has now made carbon nanotube fibers that have more of the properties of individual nanotubes. They have an electrical conductivity close to copper’s, but are much stronger. They’re not quite as strong as conventional carbon fibers, but they’re much less brittle. And they’re more thermally conductive than metal or carbon fiber. That means nanotube fibers could replace these materials in existing applications in aerospace and electronics, and enable new technologies that take advantage of the fibers’ unique combination of strength, flexibility, and thermal and electrical conductivity. Pasquali envisions washable electronic textiles, lightweight wiring for planes, and eventually, more efficient wires for the electrical grid.

Teijin Aramid is now looking into various potential markets. One possibility is lightweight, multifunctional textiles for smart clothing that integrate medical sensors, antennas, and other devices, and can survive the stress of folding and resisting corrosion in the washing machine. But early applications are likely to be in markets such as electrical wiring for aerospace and defense, where every ounce of weight is critical. First, the company has to do the necessary engineering and testing to make sure the fibers can be scaled up to make a reliable product.

The fibers reported in Science have about 10 times the tensile strength and electrical and thermal conductivity of the best previously reported wet-spun CNT fibers, Pasquali said. The specific electrical conductivity of the new fibers is on par with copper, gold and aluminum wires, but the new material has advantages over metal wires.

For example, one application where high strength and electrical conductivity could prove useful would be in data and low-power applications, Pasquali said.

“Metal wires will break in rollers and other production machinery if they are too thin,” he said. “In many cases, people use metal wires that are far more thick than required for the electrical needs, simply because it’s not feasible to produce a thinner wire. Data cables are a particularly good example of this.”

This light bulb is powered and held in place by two thin strands of carbon nanotube fibers that look and feel like textile thread. The nanotube fibers conduct heat and electricity as well as metal wires but are stronger and more flexible.

ABSTRACT – Broader applications of carbon nanotubes to real-world problems have largely gone unfulfilled because of difficult material synthesis and laborious processing. We report high-performance multifunctional carbon nanotube (CNT) fibers that combine the specific strength, stiffness, and thermal conductivity of carbon fibers with the specific electrical conductivity of metals. These fibers consist of bulk-grown CNTs and are produced by high-throughput wet spinning, the same process used to produce high-performance industrial fibers. These scalable CNT fibers are positioned for high-value applications, such as aerospace electronics and field emission, and can evolve into engineered materials with broad long-term impact, from consumer electronics to long-range power transmission.

30 pages of supplemental material

SOURCES – Rice University, Technology Review, Science

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