Bayer claims carbon nanotubes process advance

Leverkusen, Germany -- High manufacturing costs have, to date, prevented the commercial exploitation of carbon nanotubes. The microscopic materials are typically produced by the gram and require cleaning via a complex and expensive process that can push their cost up to around Euro100,000/kg.

Bayer Technology Services, however, claims to have developed a method of manufacturing high-quality tubes much more cost-efficiently. The method produces nanotubes that are virtually free of impurities and, depending on the catalyst, can vary the appearance and properties precisely to customer specifications.

Since spring, 2007, Bayer has developed capacity to supply 60 tonnes of microscopic carbon tubes, with diameters in the nanometer range. The nanomaterials, it claims, are very strong, withstanding mechanical loads 60 times better than steel, at only one-sixth the mass and can conduct electricity as well as copper.

Bayer processes the nanotubes together with plastics to create new composite materials, such as electrically conductive plastic fenders for cars.

“Conductive plastics can be painted by an electrostatic method that is better for the environment,” according to team member Dr. Heiko Hocke. Until now, he said, this method was only possible in combination with a complex primer coat.

Another target application area for Bayer is rotor blades for wind power turbines, which must withstand high stresses from fluctuating over a wide range depending on whether a rotor is in a vertical or horizontal position. Because path velocity increases toward the tip of the blades, their design must be carefully engineered.

The turbines have three rotor blades made of a glass/carbon fibre hybrid fabric. Each blade typically measures some 60 metres long and can weigh about 18 tonne These dimensions stress the material to its limits and represent the height of current technical feasibility.

“Conventional materials will never be able to exceed those limits unless they are combined with our nanotubes,” says Martin Schmid, carbon nanotubes business manager at Bayer MaterialScience.