FIG. 7 is a scanning electron microscope (SEM) image of a surface of a nanofiber which is magnified 300 times. The polymer fiber is manufactured by an improved electrospinning process developed by Korean scientists.
Korea Research Institute of Chemical Technology (KRICT) (Daejun, KR) researchers disclose filament type nano-sized long fibers and a method of producing the fibers in U.S. Patent Application 20100021732. In the KRICT method, a spinning solution or a spinning melt is electrospun in drops using a spinneret to which a critical voltage is applied, and the spun drops are continuously collected on a multi-collector.
The spinning solution is produced dissolving a blend or copolymer consisting of two or more kinds of polymers in a solvent. The spinning melt is produced by melting the polymers. The multi-collector is selected from the group consisting of a plate type collector, a roll type collector, and a combination thereof. The filament type nano-sized long fiber is processed into a yarn through one step during the electrospinning process, and thus, mechanical properties are better than those of conventional nanofiber non-woven fabric. Consequently, the filament type nano-sized long fiber can be utilized for numerous applications, say inventors Jae-Rock Lee, Seung-Yong Jee, Hyo-Jung Kim, Young-Taik Hong, Seok Kim and Soo-Jin Park.
A filament type nano-sized long fiber, which is produced using KRICT’s improved electrospinning process has mechanical properties that are better than a conventional nanofiber non-woven fabric. The KRICT nanofibers can be applied as a substitute to all fields employing a conventional fiber having a micron-sized diameter. For example, first, the fiber is useful as medical filters for kidney dialysis and purification of the blood, and various membrane reinforcing materials for genetic separation.
Second, the fiber is useful in the production of ultra-thin reinforcing films and ultra-slim PCBs in electric/electronic fields. Third, the fiber may be useful for ultra-small and ultra-light flying bodies or unmanned flying robots. Fourth, the fiber is useful as a reinforcing material for an optical cable in an optical communication field.
The nanofibers are spun from polymers. The polymers are a mixture of two or more selected from the group consisting of polyimide, polyamide, polyethylene, polypropylene, polyester, polyvinylidene fluoride, polyacrylonitrile, polysulfone, and polyethylene oxide.
FIG. 11 is a SEM image of a surface of a nanofiber produced which is magnified 300 times
FIG. 15 is a SEM image of a surface of a nanofiber produced according to the conventional electrospinning process employing the single collector, which is magnified 300 times; and
FIG. 16 is a SEM image of the surface of the nanofiber produced according to the conventional electrospinning process employing the single collector, which is magnified 20,000 times.