Recycling is important for resource and climate protection, but at the same time it is only one of many factors on the way to sustainable production and circular value creation. HSBI researchers from the InCamS@BI transfer project meet in the plastics analysis laboratory and discuss various strategies. Central to this: identifying the point in the life cycle of products that consumes the most resources and starting right there.





Bielefeld (hsbi). "Plastics are often portrayed as a problem - but we can't do without them, after all, plastic applications are the solution to many problems. Clean drinking water from PET bottles or sterile medical products packaged in plastic are just two examples of this. What we need to change, is our approach to plastics," explains Dr. Matthias Pieper as he cuts up a piece of fabric and clamps a sample of it into an infrared spectrometer . The chemist is a technology scout in InCamS@BI, the Innovation Campus for Sustainable Solutions, a transfer project of Bielefeld University of Applied Sciences (HSBI) and Bielefeld University. Together with his colleagues Katharina Schnatmann and Melina Gurcke, he talks about recycling and other strategies that are essential for sustainable production and circular value creation on the occasion of World Recycling Day. At InCamS@BI, a total of seven research groups are working on developing ideas for a circular economy for plastics. "In our plastics analysis and materials testing research group, we analyze the processing and physical properties of plastics, because recycled materials can only be a high-quality substitute for virgin material if they are suitable," says Pieper. He is demonstrating the methods used by the plastics technicians today in the HSBI laboratory for plastics analysis.





Recycling is a question of quality



World Recycling Day was first proclaimed in 2018 by the Global Recycling Foundation . Since then, March 18 has been used annually to draw global attention to the fact that recycling is essential for resource conservation and climate protection. According to the foundation, recycling can save over 700 million tons of CO2 emissions worldwide every year , create jobs and protect our natural resources of water, air, oil, natural gas, coal and minerals.



However, effective recycling is a question of quality: "In order to be able to carry out meaningful recycling, you first need good logistics, i.e. separation of the mixed plastic waste by type," says Katharina Schnatmann, research assistant at HSBI. "This is often only the case for post-industrial material, i.e. excess material and waste material during production. The company naturally knows which plastic it is, there are no signs of wear, ageing of the material, etc., so recycling this material is very effective. Recycling this material is therefore very effective. But the contents of the yellow bag or the recycling garbage can, also known as post-consumer material, are often difficult to separate properly, as many products are made of composite materials - there are very different compositions and qualities." This means that not everything can be recycled from the yellow bag: According to the Federal Environment Agency, the actual feed rate achieved for mechanical recycling of plastic packaging in 2022 was 67.5%. As the quality is usually significantly worse than that of the source materials, this is referred to as downcycling. It is therefore more of a downward spiral than a cycle, because After being recycled several times, the plastics can often only be thermally recycled. In other words, they are incinerated to generate district heating or provide energy for cement works.



Recycling changes the properties of the material



The three technology scouts Pieper, Schnatmann and Gurcke observe how the spectrometer buzzes briefly and only seconds later a curve diagram appears on the screen. Pieper himself is a chemist and explains the results to his colleagues, who are both electrical engineers: The red material sample is most likely polyethylene terephthalate, or PET for short, the material from which bottles, films and textile fibers are made. The sample of the material comes from the Bielefeld-based textile manufacturer fast52, which is working together with InCamS@BI to make its materials recyclable in future. For fast52, it is essential to recycle textile remnants and returns. However, this requires precise knowledge of the properties of the material. "As a rule, we don't have one hundred percent certainty with a single method - the analysis is very complex," reports Pieper, adding with a smile: "What you see on TV shows like CSI Miami unfortunately doesn't work in reality: it's not possible to examine a sample on just one device and immediately know what material it is and where the product comes from. For to work, we would need a digital product passport." Such a passport could be a basis for customized recycling and is one of the ideas being pursued in the Smart Recycling Factory project.





We move on to the next station, thermogravimetric analysis. Matthias Pieper uses a burner to clean the tiny sample container, a crucible. Once this has burned out and is therefore free of residues, the sample - again a small piece of the material - can be placed in the crucible using tweezers . The crucible itself looks like a tiny basket, which is then mechanically hung on a hook before being heated to 750 degrees Celsius in a small furnace. The sample is now completely burnt and the device measures the mass loss. This in turn tells the scientist at what temperature low-molecular compounds evaporate or degradation reactions take place. "What we can also see with this method is whether auxiliary materials such as glass fibers are processed in the plastic, because these remain after incineration," says Pieper. Another hurdle that can make recycling more difficult.



The three of them now move on to the last station in this laboratory: dynamic differential scanning calorimetry. Here, the scientists learn more about temperature windows in which physical and chemical processes that require or release energy take place. This allows important parameters such as the glass transition and melting temperature of the plastic sample to be determined.



This is evident in all analyses: Every recycling process changes the properties of the plastics. Mechanical recycling or thermal stresses such as melting or mixing with additives shorten the long polymer chains that make up plastics, which changes the processing temperatures or viscosity. Mechanical properties such as tensile strength or impact strength also change. However, all these properties are extremely important for the various production processes.



R-strategies for sustainable product design



In addition to recycling, InCamS@BI also looks at other approaches, so-called R-strategies, which can be used to make products more sustainable. In order to discuss the strategies using concrete objects, the group goes to an office of the InCamS@BI research group Circular Value Creation, which is based at ITES, the HSBI Institute for Technical Energy Systems. Melina Gurcke and Katharina Schnatmann deal with circular value creation (also known as the circular economy, see info box) on a daily basis. The "R strategies" are as follows: Refuse, Rethink, Reduce, Replace, Reuse, Repair, Refurbish, Remanufacture, Repurpose, Recycle and Recover (energy recovery).





But what do these strategies achieve in individual cases? How do you know which one to use? Katharina Schnatmann explains: "We look at the entire life of a plastic product and divide it into three phases: In the production or design process, it is important to either make a product or parts of a product dispensable, design them so that they can be used more intelligently or manufacture them more intelligently. Refuse, Rethink, Reduce, Replace. The use phase of products or individual components can either be extended or their impact on the environment reduced: Reuse, Repair, Refurbish, Remanufacture, Reuse. And at the end of a product's life, you should think about how the individual materials can be sensibly reused or at least recovered for energy : Recycle or Recover. The earlier in the life of a product you start, the more energy and raw materials can ultimately be saved."



On the table between the three InCamS@BI employees are various items made partly or entirely of plastic. The group looks at the objects from the point of view of energy consumption: a small plastic bag, a kettle, a water bottle, a multimeter and a crimping tool. The products belong to different categories: Disposable products such as the sachet or the PET bottle have a very short useful life. The long-life products can also be subdivided again: Tongs have a low negative impact on the environment, because they only cost energy to produce but can be used for a long time afterwards . A kettle, on the other hand, consumes the most energy during its use phase and therefore has a high negative impact.

"Long-lasting products with a positive impact, such as photovoltaic modules, are particularly good. They cost energy during production, but then generate significantly more - until the end of their life. Nevertheless, it is also important here to think about any problems that could arise at the end of their life as early as the development stage," reports Katharina Schnatmann.



Companies need to start thinking in cycles



The aim of the scientists is to encourage companies to rethink: "Recycling is rarely the best solution - it usually costs a lot of energy and leads to recyclate of poorer quality, which can 'only' be used in the production of flower pots or artificial turf pitches, for example," says Gurcke, whose focus is on energy technology in circular value creation. "A company that manufactures products - and this doesn't just apply to plastics processing companies - must always ask itself in which phase of life the product consumes the most resources. At the start of production? During use? Or at the end of its life through recycling? And the point at which the most resources are used should be the starting point. Recycling can only be sustainable if the process is efficient and the energy used is generated from renewable sources." The R-strategies are a good basis for this.





Pieper picks up the multimeter, a measuring device for electrical parameters, and turns and twists it. The housing and cable sheathing are made of plastic. What strategies could be used here? His colleague Schnatmann explains: "A device like this basically has a very long service life. Years or even decades pass before it breaks down. Manufacturers can start here and design the multimeter in such a way that parts that wear out quickly, such as push buttons or keys, can be easily replaced and the device can be repaired again and again. Completely new systems such as sharing tools could also be considered - this would increase the use of the tools." The chemist suggests: "The choice of plastics in production could also be reconsidered in order to improve recycling at the end of the product's life - do there have to be five different types or would two be enough? That would be the Rethink strategy." Regardless of which of the R strategies is used, all of these paths lead to a more sustainable product in the circular value chain.



An economic system based on value preservation



In their discussion, Pieper, Gurcke and Schnatmann also repeatedly refer to legislation: For example, there is a lack of binding specifications and standards. The Circular Economy Act primarily regulates waste. However, there is hope that the National Circular Economy Strategy of the federal government will take a more holistic approach.





Basically, it's always about one thing: preserving value. For truly circular value creation, however, this rethink is needed not only in the economy, but also in politics and among consumers. Because our society can only achieve this transformation to a new economic system together.

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About InCamS@BI

With InCamS@BI, the Innovation Campus for Sustainable Solutions, HSBI is positioning itself as an innovative transfer player in the field of the circular economy. In the interdisciplinary project, ideas are generated and solutions developed to optimize plastics and their handling for a circular economy. With innovative formats and an interdisciplinary team, InCamS@BI shapes the exchange between science, business and society. In the project, research-based transfer structures are systematically developed, established and tested. InCamS@BI is funded as part of the federal-state initiative "Innovative University" from 2023 to 2027. Further information:  www.hsbi.de/incamsbi