Erhöhung des Formfaktors in der Filamentextrusion durch die Entwicklung modifizierter Kapillaren

  • Increasing the shape factor in filament extrusion by developing a capillary modification

Noll, Inga; Gries, Thomas Gerhard (Thesis advisor); Seide, Gunnar (Thesis advisor)

Düren : Shaker (2019)
Book, Dissertation / PhD Thesis

In: Textiltechnik/Textile technology
Page(s)/Article-Nr.: 295 Seiten : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2019


In the textile industry, more than 20 % of the obtained revenue goes back to product innovations. Here, an intensified use of fibers with a noncircular cross-section is observed. Compared to round fibers, noncircular fibers enable a targeted functionalization of textiles due to their increased surface area, notches or cavities. In particular, for noncircular fibers, the development of spinning nozzles is very time consuming. This goes back to the die swell effect as for which the relaxation of the polymer at the die exit leads to a low conformity between the desired and the realized cross-sectional shape. Therefore, multiple iteration steps are necessary to obtain the geometry of the capillaries of the spinning nozzle. Hence, the production of individual shaped fibers is inefficient and limits the degree of innovation of fiber and textile producers. The aim of this work is to reduce the time for spinneret development for novel fiber geometries. The approach is to manufacture capillaries with uniformly in-creasing cross-sections. Therefore, the relaxation of the polymer, which leads to the die swell, is shifted into the capillary. The stress reduction is controlled. Thus, the resulting fiber cross section can be traced back to the capillary geometry. Within the scope of this work, the influencing factors on the shape formation in the extrusion of noncircular fibers under variation of polymer types and process parameters are investigated. Modified capillaries with different expansion lengths and angles are developed in the sense of a statistical design of experiments. The shape factor of the extruded filaments is quantified by developing a geometry-independent, partially automated shape factor determination method. The capillary modification, the shape factor determination method as well as knitted fabrics made of cruciform filaments are evaluated technologically and economically from a product, process and application point of view.


  • ISBN: 3-8440-6931-3
  • ISBN: 978-3-8440-6931-0