A newly published peer reviewed open-source paper from a team of authors working within the MultiCycle project reviews how current progress in photonic sciences in combination with advanced (e.g. AI based) data analysis is bridging the gap to a solution to the recycling industry’s practical challenge of automatically identifying and monitoring the composition of complex multi-material plastic waste streams.

In the increasingly pressing context of improving plastics recycling, optical monitoring technologies present a broad potential for utility. Currently available commercial solutions (for example, employing near-infrared spectroscopy) however generally focus on identifying mono-materials of a few selected types which currently have a market-interest as secondary materials.

In the new paper, which appears in the March 2021 edition of Waste Management & Research: The Journal for a Sustainable Circular Economy, a joint authorial team from IRIS Technology and the Fraunhofer Institute for Process Engineering and Packaging IVV, review the main characteristics of the range of relevant photonic techniques, then (based on academic literature) discuss their suitability for monitoring the composition of multi-materials, such as different types of multi-layered packaging and fibre-reinforced polymer composites as well as black plastics used in the motor vehicle industry, and finally present some commercial systems with applications in those sectors.

The extensive review, providing over 160 references to further reading, mainly focuses on the materials identification step which takes place after waste collection and before sorting and reprocessing, but also offers an outlook on further insights for sorting and future prospects which can contribute to increasing the circularity of the value chain for plastic composites.