Manufacturing Ultra Fine Filaments by Cold Air Attenuation

Ultra fine fibers, with a linear density below 1 denier, are high value products for textile, industrial and biomedical applications. Traditionally ultrafine fibers are produced by extrusion followed by mechanical drawing. In this study a customized fiber extrusion line was designed and set up with the inclusion of a jet nozzle in the spinneret pack. With only cold air attenuation, we were able to obtain drawing ratios exceeding 2500 and produce subdenier continuous filaments. We have conducted parametric studies to investigate the fiber attenuation mechanism and determine the optimal process window for making continuous microfibers. Different characterization methods were carried out to examine the resulting fiber properties, including microstructures, thermal properties, mechanical properties, orientation and crystallinity. Theoretical analysis of cold air drawing is discussed in this paper.