The DITF‘s Competence Center for Man-Made Fibers and Nonwovens is working on the development of ultra-fine fiber nonwovens with fiber diameters in the sub-micrometer and nanometer range. A contribution is also being made to the BMWK‘s “hydrogen technology offensive” in this field of work through the ongoing “FLUID” project. Together with the companies FUMATECH BWT, BASF and Spiraltec and colleagues from the Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB), the DITF have set themselves the goal of developing and validating both new types of fluorine-free flat membranes and a new type of module design for membrane humidifiers for use in PEM fuel cells.
Ultra-fine fiber nonwovens are used as “super-thin” support structures for the project partners‘ membranes and consist of sophisticated high-performance polymers such as PSU, PESU, PPS or PEEK. Some of these polymers can only be processed from the melt at temperatures of over 400 °C using the established meltblow process (MB) or alternatively using the centrifuge electrospinning process (CES) from solvents to produce ultra-fine fiber nonwovens. In the latter case, the project is also investigating the influence of increasing the process enthalpy by introducing hot air on successful fiber formation.
The illustration uses the example of PESU fibers spun from a green solvent to show the difference in the final fiber diameter that just a few Kelvin temperature difference can lead to. These ultra-fine fiber nonwovens can also be subsequently bonded and stabilized using thermobonding or ultrasonic calendering. The first prototypes have already been successfully produced and will be optimized as the project progresses.
