Originally Published MPMN July/August 2005
Machine Spins Nanofibers in Industrial Quantities
|A rotating cylinder, in lieu of nozzles, enables the industrial-scale electrospinning of nanofibers.|
A young company from the Czech Republic generated a great deal of electricity in Geneva, Switzerland, in April. Exhibiting at Index, the world’s largest nonwovens show, Elmarco (Liberec) demonstrated Nanospider technology, a variation on the electrospinning process. This decades-old technique extracts nanoscale polymer fibers from a charged jet of polymer melt. What drew the crowds to Elmarco’s stand was the unveiling of a machine that could do this on an industrial scale. The resulting materials have a range of applications. On the medical side, filtration and wound-care products are especially promising, according to the firm.
“Traditional systems use a nozzle-shaped spinning head to produce nanofibers,” explains marketing and sales manager Petr Kuzel. An electrostatic field competes with the polymer solution’s surface tension to form a Taylor cone. The fiber jet is drawn from the cone to a grounded plate, where the material collects in the form of a nonwoven mat composed of fibers with diameters between 50 nm and 10 µm.
The system’s architecture makes it “impossible to position several nozzles next to each other,” says Kuzel. “That limits the production quantities that can be achieved using the traditional method.” Researchers at the Technical University of Liberec (TUL) found a way to overcome this limitation.
“Nanospider technology produces Taylor cones in close proximity to each other on a cylinder,” says Kuzel. The cylinder is partly immersed in a polymer solution. A controlled amount of the polymer solution creates a thin film on the cylinder’s surface, where a number of Taylor cones are formed. The machine can produce nanofibers weighing between 0.1 and 10 g m2 in diameters ranging from 50 to 500 nm. Nanospider technology can produce 0.1 to 1g of material in less than 1 minute. By comparison, it would take as much as 1 hour to achieve the same result using traditional electrospinning techniques, says Kuzel.
Elmarco entered into a cooperative agreement with TUL in 2004 to refine the technology. The company holds the exclusive license for its development, production, and commercialization.
Although Elmarco is eyeing high-yield industrial applications, the resulting material’s unique properties make the technology of interest to medical partners as well. For example, nanofibers feature exceptionally small pore sizes and a large functional area combined with low weight. This makes them suitable for advanced filtration applications in medical equipment.
“Wound dressings are another area we are investigating,” says Kuzel. “We have completed some very promising tests on the use of biodegradable polymers to fabricate dressings and other healing materials.”
Elmarco’s primary objective is to sell equipment incorporating Nanospider technology. “But for some low-quantity applications where material properties are paramount, such as biomedical products, we may opt to keep production in-house,” says Kuzel.
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