New dynamic characterizing method for micro filtration membranes
Herbert Reingruber
15:00 - 16:00 Tuesday 01 June 2010 KFU Graz, Hoersaal 05.12

Most methods for the characterization of porous membranes yield macroscopic parameters for the description of the respective materials. Only very rarely do they provide information about the transport of fluids in membranes on a µm-scale. In this work a new microscopic method for the characterization of fluid transport in membranes are presented.

The specimen chamber of an Environmental Scanning Electron Microscope (ESEM) forms a micro-laboratory, where a multitude of dynamic experiments can be performed. For example, the investigation of the wetting and drying of porous membranes can be carried out on a µm-scale. It provides, amongst others, information about the dependence of the number of dry pores and their size determined wetting behavior as a function of time. This information cannot be gained by conventional test procedures.

For the better understanding of the wetting and drying process two micro-thermocouples (70 µm diameter) from Omega® Newport were attached at both membrane surfaces to measure their temperatures during the experiment. Simultaneously pictures of the membrane surface were taken at high magnification for documentation the drying behavior of the membrane.

The membrane DuraPES TM450 from Membrana™ shows a very inhomogeneous porosity profile: large pores at one surface compared to very small ones at the opposite surface. This property leads to a behavior which can be observed in the temperature-time curve. In addition in situ ultramicrotomy is used to get quantitative 3D information of the very complex internal membrane structure.