Nanotechnologies for coating and structuring of textiles

There are many ways to implement nano-scale controlled properties into textiles. One is to give the fiber itself a nano-scale by fiber spinning. With novel fiber spinning technologies it is possible to spin fibers with diameters between 20 and 500 nm 10-500 times thinner than fibers spiimable by traditional fiber spinning techniques. An aim is to make the production of fibers with diameters below lOOnm highly productive and state-of-the-art. 

In order to achieve effects from nanostructures in the fiber bulk either 

Production of nanofiber nonwovens using electrostatic spinning 

Porosity and pore size are crucial properties of filter media, which determine efficiency as well as pressure drop and permeability. Small pore sizes at high porosity of a textile filter medium depend on the fiber size. A reduction of the pore size below the fiber diameter greatly reduces the porosity and diminishes the permeability, which means the filtration efficiency increases with a reduction in the fiber diameter. 

The basic design of electrostatic spinning and its realization in most research laboratories is very simple (Fig. 15.2). A polymer solution is fed to a nozzle by a defined low pressure. An electrical field is applied between the nozzle and a collector (rotating mandrel or a conveyor belt). The application of the voltage on the nozzle or the carrier is not important initially. The application of positive or negative charges is mandatory. Independent of the polymer, solvent and the concentration of the solution, a voltage of 1 kV per centimeter between the nozzle and the collector of the spun fibers is useful. The nozzle diameter is usually about 100 pm. 

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