Spectroscopy and AI Keep Eye on Ageing of Plastics

Research Collaboration ON Plastic Recycling

Under the project management of Silicann Systems and in collaboration with HAIP Solutions and Fraunhofer IFF, the SKZ is launching the SpectralAIge research project. The associated challenges in waste management require innovative solutions. The SpectralAIge joint project aims to develop the world's first spectroscopic measurement systems capable of rapidly and accurately evaluating the process-induced ageing of plastic materials. With support of artificial intelligence (AI), the best possible decisions must be made for processing and use of secondary plastics in order to recognize and sort plastic material that has aged to varying degrees and directing them into the most suitable recycling pathways.

The knowledge gained from the project should make it possible to identify degraded materials within the closed PET deposit bottle cycle and plastic sorting facilities. This offers the option of making the best possible decisions for processing and utilization of secondary plastics. Sorting out excessively degraded materials at an early stage ensures higher quality of recyclate. This is essential, for example, in the production of food packaging such as returnable bottles.

Challenges due to material ageing

Plastics are repeatedly exposed to high temperatures and mechanical stress during the recycling process, usually in the extrusion and injection molding process. This can lead to ageing or degradation of the materials. If the concentration of heavily aged material in the manufacturing process is too high, the quality of the product could deteriorate and ultimately lead to the product no longer being allowed on the market due to quality defects. Although additives can compensate for these ageing processes to a certain extent, the only option for heavily aged material is downcycling or chemical recycling. However, there is currently a lack of industrial processes to quickly and reliably analyze and evaluate the ageing of plastic waste.

Research project pursues two possible approaches

In the first project approach, hyperspectral camera systems (HSI), which are already established in plastics sorting, will be expanded to include LED-based light sources for fluorescence excitation. In addition to the classic absorption spectra, excited fluorescence spectra can also be recorded. The analysis of this spectral data using AI enables the precise determination of the material ageing of plastic waste.

The second approach focuses on the development of AI-supported, inexpensive inverted spectrometers. To this end, relevant wavelengths are extracted from broadband measurement results from HSI measurements and an inverse spectrometer is built using this data. This should allow conclusions to be drawn about the process-related ageing of plastic materials. In contrast to a spectrometer, which covers a complete wavelength range, an inverse spectrometer only covers specific individual wavelength bands. This allows production costs to be reduced and a wide range of industrial applications to be achieved.

Economic potential

“The knowledge gained from the research project can be used to promote a wide range of economic applications and enable SMEs to move towards a circular economy through the optimal use of secondary plastics,” says Frank Stüpmann, Silicann Systems Managing Director. “We hope that the packaging sector, among others, will benefit greatly from the developments in the project. This generates the largest proportion of post-consumer (PC) plastic waste and there are short product life cycles and consequently frequent processing,” adds Dr. Linda Mittelberg, Head of Quality and Life Cycle at SKZ. “The results can be used in PET deposit bottle cycles and plastic sorting plants in particular.”

Five project partners for innovative solutions

The joint project SpectralAIge is carried out together with the medium-sized technology companies Silicann Systems, Rostock and HAIP Solutions, Hanover, as well as the two research organizations Fraunhofer Institute for Factory Operation and Automation IFF, Magdeburg, and the Plastics Center SKZ, Würzburg, all in Germany.

(Source: FSKZ e. V.)