Fraunhofer Institute for Environmental, Safety, and Energy Technology UMSICHT
Fraunhofer UMSICHT sees itself as a pioneer for a sustainable energy and raw material economy. The institute provides scientific results and transfers them to companies, society and politics. Together with various partners the research institute develops and researches new sustainable products, processes and services that inspire. As one of 66 institutes and research units of the Fraunhofer-Gesellschaft, the leading organization for applied research in Europe, we are a worldwide network and promote international collaborations.
In the department process intensification, we are pursuing the overriding objective to develop more efficient and sustainable processes. To achieve this, we increase the performance and functionality of materials and components, and connect and improve water engineering and adsorption processes.
Within the framework of the strategy - nano technology for water engineering - we are developing hybrid systems and reactive separation processes, such as functionalized filters to eliminate micro pollutants and recover rare metals. In our electroplating and laser laboratory, we are developing materials and components with micro- and nanostructured surfaces, for example for friction optimization and improving material exchange processes. We are producing custom-fitted microsieves with functional surfaces and are dealing with the large-scale transfer of microtopographies.
Within the last years Fraunhofer UMSICHT has impregnated polymeric components and pre-products in compressed CO2 atmosphere. Functionalized or modified surfaces, respectively, could be achieved. The extraction of monomers and production residues like fats and oils is also possible. The CO2 process stands out due to the reduced input of additives and solvent; to name just a few advantages. Transferring the product vision from lab scale into industrial realization is the strength of Fraunhofer UMSICHT. According to their dimensions the polymeric parts (injection molded parts or pellets, powder etc.) are arranged in the high pressure autoclave (63 mL, 1,5 L, 2 L, 20 L, 1700 L). Depending on the aggregation state (e.g. liquid, powder form) the additive is added inside the autoclave. Pressurizing the autoclave with CO2 initiates the impregnation process. CO2 acts as a molecular lubricant enabling substances to pass the polymeric matrix. To intensify the absorbing capacity of the polymer the process chamber can be heated during the process (usually not above 100 °C). Finally the autoclave is depressurized (the CO2 can be reused in the next process) and the parts can be removed. The parts are now impregnated. The use of compressed CO2 opens a wide range of applications. It is possible to impregnate, extract and foam polymeric components and pre-products. Up to now surfaces have been modified either by coating the component or by filling the whole volume with the additive during the injection molding. CO2 impregnation offers the possibility to accumulate the additives only in the area near the surface, reducing the input of additives.
Extraction of monomers, fats and oils
Foaming of polymers
Additives for impregnation: Nanoparticles, e.g. silver, titanium dioxide, graphite, dyes and a wide range of other CO2-soluble and insoluble additives
The following polymers have already been treated successfully: PS, PMMA, PVC, PC, PE, PET, PA, TPU etc.
CO2 is non-flammable, relatively inert, non-carcinogenic, non-mutagenic, shows a very low toxicity and is inexpensive. By compressing CO2 it shows solubility of liquids and penetration of gases and exhibits excellent heat and mass transfer properties. CO2 is able to penetrate into solid structures, to change material properties and to enable the transport of other substances into or out of solid structures. The gaseous CO2 employed can be recycled after processing and can be reused in the next process cycle. Most of the CO2 employed in processes today accumulates as byproduct in processes like ammonia production so that the CO2 has not to be counted as »emitted CO2«.