The only way to keep water from freezing in tanks servicing the Ryuhyo-Norokko train running through Japan’s cold north islands has been potbellied stoves—until now. The J.R. Hokkaido Railway Company is testing a woven fabric heater that does the job, thanks to applied coatings of carbon nanotube technology that increase electrical and thermal conductivity in multifilament yarns.
Bayer MaterialScience AG, Leverkusen, Germany, produces Baytubes® carbon nanotubes (CNTs) in industrial quantities, which can be blended into aqueous suspensions and used to make yarns that conduct electricity. The J.R. Hokkaido line is testing tank heaters and seat heating in its rail cars made by weaving conductive yarns from Kuraray Living Company Ltd., Osaka, Japan, into flexible, lightweight fabrics. CNTs usually form large, tangled agglomerates that don’t conduct electricity well. However, a dispersion technology invented by Dr. Bunshi Fugetsu from Hokkaido University allows CNT breakdown into single tubes that can conduct electricity and be produced in industrial quantities. The fabric heaters are the first commercial use of Baytubes.