Material Characterisation and Processing


PMM Junior


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.


Pendelum impact testing machine

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.

Hollow fiber membranes are widely used for the treatment of drinking and industrial water as well as for medical applications (e.g. for hemodialysis). They are bundled in modules so that the high ratio of membrane area to module volume makes the application attractive for numerous separation processes.
We are developing new hollow fiber membranes based on homopolymers and block copolymers.
The hollow fiber membranes are produced by a spinning process. In order to obtain membranes with the highest possible permeability and selectivity, the synthesis and modification of the polymers as well as the optimization of the process parameters for spinning are of paramount importance. For this reason, the process engineering principles of hollow fiber spinning are extensively investigated.
Depending on the required property profile of the membranes, the spinning solutions are adapted individually and the process conditions required for the spinning process are determined in complex trial series. The subsequent characterization of the membranes obtained is of crucial importance as the development of the membranes is specifically advanced by this feedback.