Membrane processing

Hollow fiber membranes offer the advantage of a large specific separation area. Spinnerets are available to manufacture fibers with outer diameters in the range of 0.5 to 4 mm and wall thicknesses from 50 to 500 μm. Our main focus lies in the processing of inorganic or metallic slurries and spinning of biodegradable or biocompatible polymers. Asymmetric structures can be obtained by controlling the phase inversion process.

Flat membranes with thicknesses between 20 and 200 μm can be manufactured. Both temperature and atmosphere can be controlled during casting. Precipitation baths with temperatures between 4-90 °C are available. The main focus at Fraunhofer IGB lies in the processing of mixed-matrix systems. Both dense and asymmetric porous membranes can be obtained by solvent evaporation and phase inversion processes respectively.

Hollow fibers (< 0.5 mm), capillaries (0.5 – 3 mm) and tubes (up to 10 mm) can be processed with our piston spinning equipment. The parameters of extrusion can be varied from RT up to 320 °C and from 1 to 300 bar. Material amounts ranging from 10 to 500 g can be processed to membranes. Due to low material consumption expensive materials like biopolymers, noble metal-doped materials or valuable ceramics can be used.

We use electrospinning methods to develop very thin fibers (50 nm – 10 μm). Electrospun nonwovens can be used as very open support structures, as porous matrices for the cultivation of cells or as a filter layer with a good retention for very small particles. Beside polymeric fibers like PLA pure ceramic fibers can also be obtained by adding suitable precursors and sintering.