Hmm. This looks pretty significant. A breakthrough has allowed the downsizing to the nanoscale of methods used to spin wool and other fibers to produce futuristic yarns made from carbon nanotubes. Details from the Aug 19 edition of Science, via www.eurekalert.org.
I seem to recall that nano-tube “cables” are one of the requirements for the Space Elevator concept. Arthur C. Clarke is usually crediting with introducing this concept to a broader audience. In his 1978 novel, Fountains of Paradise, engineers construct a space elevator on top of a mountain peak in the mythical island of Taprobane (closely based on Sri Lanka, the country where Clarke now resides). The builders use advanced materials such as the carbon nanofibers… See www.spaceelevator.com, the Wikipedia entry and this 2002 article from Space.com.
And the details of the nano-yarn…
University of Texas at Dallas (UTD) nanotechnologists and an Australian colleague have produced transparent carbon nanotube sheets that are stronger than the same-weight steel sheets and have demonstrated applicability for organic light-emitting displays, low-noise electronic sensors, artificial muscles, conducting appliques and broad-band polarized light sources that can be switched in one ten-thousandths of a second.
Carbon nanotubes are like minute bits of string, and untold trillions of these invisible strings must be assembled to make useful macroscopic articles that can exploit the phenomenal mechanical and electronic properties of the individual nanotubes.
Starting from chemically grown, self-assembled structures in which nanotubes are aligned like trees in a forest, the sheets are produced at up to 7 meters per minute by the coordinated rotation of a trillion nanotubes per minute for every centimeter of sheet width. By comparison, the production rate for commercial wool spinning is 20 meters per minute.
Strength normalized to weight is important for many applications, especially in space and aerospace, and this property of the nanotube sheets already exceeds that of the strongest steel sheets and the Mylar and Kapton sheets used for ultralight air vehicles and proposed for solar sails for space applications, according to the researchers.
The nanotube sheets can be made so thin that a square kilometer of solar sail would weigh only 30 kilograms. While sheets normally have much lower strength than fibers or yarns, the strength of the nanotube sheets in the nanotube alignment direction already approaches the highest reported values for polymer-free nanotube yarns.
The nanotube sheets combine high transparency with high electronic conductivity, are highly flexible and provide giant gravimetric surface areas, which has enabled the team to demonstrate their use as electrodes for bright organic light emitting diodes for displays and as solar cells for light harvesting. Electrodes that can be reversibly deformed over 100 percent without losing electrical conductivity are needed for high stroke artificial muscles, and the Science article describes a simple method that makes this possible for the nanotube sheets.
The use of the nanotube sheets as planar incandescent sources of highly polarized infrared and visible radiation is also reported in the Science article. Since the nanotube sheets strongly absorb microwave radiation, which causes localized heating, the scientists were able to utilize a kitchen microwave oven to weld together plexiglas plates to make a window. Neither the electrical conductivity of the nanotube sheets nor their transparency was affected by the welding process, which suggests a novel way to imbed these sheets as transparent heating elements and antennas for car windows. The nanotube sheets generate surprisingly low electronic noise and have an exceptionally low dependence of electronic conductivity on temperature; that suggests their possible application as high-quality sensors, which is a very active area of nanotube research.
“Rarely is a processing advance so elegantly simple that rapid commercialization seems possible, and rarely does such an advance so quickly enable diverse application demonstrations; synergistic aspects of our nanotube sheet and twisted yarn fabrication technologies likely will help accelerate the commercialization of both technologies”
Link: www.eurekalert.org.