Institute of Membrane Research
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Preparation of Hollow Fiber Membranes via Spinning, Photo: HZG/general

Material Characterisation and Processing

The research of the Department "Material Characterisation and Processing" is dedicated to the development and characterisation of nanostructured materials for membrane applications as well as to the preparation of membranes.

Our research focuses on processing as well as mechanical and rheological properties of nanostructured materials. Thermal and dielectric properties of polymer materials are also investigated. Structure-property relationships are established in order to predict the behaviour of materials in complex loading and flow situations, mainly for the development of membranes.

Furthermore, we develop innovative methods for sustainable production of membranes. Foam extrusion and sintering are examples of solvent-free processes for preparation of membranes. The analysis of these manufacturing processes is an important part of our research on nanostructured materials.

A wide range of nanostructured polymer materials is covered (block copolymers, polymer blends and nanocomposites) by our research. Morphological studies (phase separation, dispersion of nanofillers and orientation phenomena), analysis of the viscoelastic properties (mechanical and rheological experiments) as well as polymer processing are part of our work. In this way, we explore the basic mechanisms for the production of polymer membranes.

Profile

Extrusion, Photo: HZG/Christian Schmid

The research of the department is devoted to the processing of nanostructured materials and the investigations of their rheological, mechanical, thermal and dielectric properties. In a cross-department manner we receive important insights for the optimisation of new developments of the institute.

Various methods for polymer processing and membrane production are used: extrusion, compression moulding, injection moulding, hollow fiber spinning, foaming of polymers.

Schlagprüfmaschine

Pendelum impact testing machine, Photo: HZG/Christian Schmid

Static and dynamic mechanical test methods allow to determine mechanical parameters in tension, compression and shear.
These tests provide information about the mechanical and rheological properties over a wide temperature and deformation range.

The research focus of our department:

Nanostructured materials, e.g. block copolymers and nanocomposites, have a high potential in membrane technology. The development of membranes based on nanostructured materials requires a thorough understanding of the physical mechanisms and chemical interactions during membrane production. An important example is the phase inversion process in the manufacture of integral asymmetric membranes by flat drawing and hollow fiber spinning.
The goal of our research is the systematic analysis of the properties of polymeric materials for use as membranes and the optimization of technological processes for membrane production.

Manufacturing of membranes using the phase inversion process generally involves organic solvents. To reduce the use of organic solvents, solvent-free processes for membrane production are developed in the Department of "Material Characterisation and Processing." Examples include the production of open-celled polymer foams by means of foam extrusion and sintering of polymer particles. To optimise these processes, a detailed understanding of the rheological properties of the polymers as a function of temperature, deformation mode, and deformation rate is of high relevance. We also investigate the effect of external media (e.g., in a high-pressure gas atmosphere) on the mechanical and rheological properties of the polymers.

Permeability and selectivity of membranes may decrease during the period of application due to a variety of phenomena. Using theoretical and experimental methods, the physical ageing of polymer membranes is fundamentally investigated. Examples are the mechanically induced compaction of porous membranes and substrate materials and the ageing of dense polymer membranes for gas separation. Various methods and models are used to describe ageing. The modeling results are compared with experimentally determined data.

Permeability and selectivity of membranes may decrease during the period of application due to a variety of phenomena. Using theoretical and experimental methods, the physical ageing of polymer membranes is fundamentally investigated. Examples are the mechanically induced compaction of porous membranes and substrate materials and the ageing of dense polymer membranes for gas separation. Various methods and models are used to describe ageing. The modeling results are compared with experimentally determined data.