부산대학교 도서관

A new technique for classifying fibers according to length has opened up opportunities for improving fiber measurement technology. The classification principle is dielectrophoresis, which moves conductive fibers at a velocity proportional to the square of their length. Even non-conductive fibers can be made sufficiently conductive by increasing the humidity in the classifier. A device based on this principle has been constructed. It can classify fibers from a broad distribution into length distributions with CVs in the range of 0.2–0.3 and with mean lengths selectable from about 4 μm to >50 μm. To complement this device, diameter classification readily can be achieved by gravitational or inertial techniques in combination with length classification. An inertial classifier was used to produce relatively monodisperse diameter fibers in the aerodynamic diameter range of 3 – 7 μm. This device was used to calibrate the response of the Aerodynamic Particle Sizer (APS) so that real-time diameter distributions were obtained for each length distribution from the dielectrophoretic length classifier. By varying the voltage on the length classifier, a length/diameter distribution can be produced in a matter of minutes