Today, polymer materials have become indispensable not only in everyday life but also in technical applications. In addition to traditional engineering plastics, elastomers—primarily in the form of seals—play a key role in refrigeration technology. The fundamental material properties, as well as consistent material quality, are crucial here for the trouble-free, long-term operation of the systems and for preventing refrigerant leaks. An indicator of their resistance to media—and thus an important parameter for the use of these materials—is the swelling behavior of the polymers when in contact with liquid or gaseous refrigerants (and with refrigeration oil). Until now, testing for changes in the polymers caused by storage under elevated gas pressures was only possible after they had been removed from the medium—that is, only AFTER the decompression phase. The data available to date provided only limited insight into the behavior of the materials DURING exposure to the medium and decompression, which is relevant in practical applications. This is precisely where the new in-situ measurement method comes into play.

The goal of the research project is to develop and establish a suitable testing method that enables the swelling and shrinkage processes of polymer materials to be measured in situ under process conditions, i.e., during chemical and mechanical stress (p-T). Using a transparent autoclave, a measurement setup will be constructed that is suitable for investigations in the temperature range up to 80 °C and at pressures up to 90 bar. Two alternative optical measurement methods will be employed and compared. The first consists of a camera system that records and measures the time-dependent swelling behavior of the material sample. A high-speed 2D optical micrometer will be used as the second method. The measurement method is intended to enable a time- and cost-saving evaluation of materials and to provide a foundation for the development of improved sealing materials. Thus, this research project makes a significant contribution to improving product sustainability and the safety of refrigeration systems. The ILK is the leading institute for method development and research on material behavior in the field of refrigeration technology. The in-situ method expands existing testing procedures in the areas of material aging and evaluation with an innovative measurement technique.