Feedstock recycling of PLA – a biobased polymer goes circular

Plastics from renewable resources like polylactide (PLA) are gaining more and more market share. With the proliferation of PLA, issues concerning the end-of-life options of PLA products gain more and more importance. One possibility, regarded as being the most favorable several years ago, is the processing of PLA in industrial composting plants.

However, this end-of-life scenario is an adequate route only in specific cases (such as bio-waste collection bags) as it runs counter to important social objectives such as the conservation of natural resources and the reduction of CO2 emissions. Therefore, it is essential to accompany the progressive introduction of PLA with an exploration and implementation of alternative recycling options, which can be effective in the context of a sustainable circular economy.

Since conventional mechanical recycling processes often involve a deterioration of the characteristic property profile of a polymeric material, chemical recycling can be an attractive alternative. In the lecture, we will put chemical recycling routes in the overall context of different possible recycling processes for PLA and we will present results concerning the simple reintegration of PLA waste into its technical synthesis process. The results reveal the feasibility of adding variable amounts of PLA waste into the dilactide producing process step without adversely affecting the process performance or the product quality.

The advantage of this feedstock recycling process compared to other chemical recycling options is that it runs on existing synthesis lines for PLA without significant extra investments. The chemical background of the recycling process and the results obtained for various possible PLA recycling streams will be highlighted. Additionally, a life cycle assessment of this recycling route will be presented.

A presentation by Antje Lieske, Head of Department at Fraunhofer Institute for Applied Polymer Research.

Interview

Question 1: What drives you?
As global warming and plastic pollution attract more and more public attention, we see our R&D work as contribution to open new routes into more sustainable and circular ways to treat plastics. We are convinced that plastics help to make our lifes easier, safer, more comfortable and also more sustainable – in case we do not deny the associated problems but actively investigate possibilities for a real circularity of this important materials and make them available for implementation.

Question 2: Why should the delegate attend your presentation?
The presentation will highlight that a biobased polymer like PLA can contribute to circularity not only by saving fossile resources but also by being recycled by different routes, dependent on the intended application of the recycled material. There is no ideal circular path that fits all needs but the route to circularity has to be adopted to material particularities and application needs. The related LCA will show that a chemical recycling of PLA to virgin qualitites saves CO2 and has positive impacts in other environmental categories.

Question 3: What emerging technologies / trends do you see as having the greatest potential in the short and long run?
Design for reuse and recycling is definitely one of the key trends to change the game in the plastic world, combined with expanded deposit systems and new sorting technologies. Also, using CO2 as raw material for building blocks for polymers.

Question 4: What kind of impact do you expect them to have?
If most of the plastic products are designed in a way that they can either be reused or disassembled into unmixed polymers and sorting facilities are able to create unmixed polymer fractions (and really do so), all options for „second lifes“ of the plastics remain open. Combined with biobased or CO2 based building blocks, a true circularity of C becomes possible.

Question 5: What are the barriers that might stand in the way?
Waste quantities, an appropriate waste collection and sorting as well as economic feasibility are crucial for the implementation. Unsolved technical problems – for instance how to avoid mixed plastics or how to provide disassembling options without loosing functionality – and economic barriers. Without purposeful incentives and regulations from politics the developments will take too long.

About Antje Lieske
Dr. Antje Lieske studied chemistry at the Humboldt University in Berlin and did her PhD on polymeric surfactants.
Since 1997 she has been working at the Fraunhofer Institute for Applied Polymer Research in Potsdam. In 2006 she was appointed head of the department “Polymer Synthesis”. Her research focuses on the development of bio-based polymers.

About Fraunhofer Institute for Applied Polymer Research
The Fraunhofer-Gesellschaft, headquartered in Germany, is the world’s leading applied research organization. With its focus on developing key technologies that are vital for the future and enabling the commercial exploitation of this work by business and industry, Fraunhofer plays a central role in the innovation process. As a pioneer and catalyst for groundbreaking developments and scientific excellence, Fraunhofer helps shape society now and in the future. Founded in 1949, the Fraunhofer-Gesellschaft currently operates 75 institutes and research institutions throughout Germany.

The Fraunhofer Institute for Applied Polymer Research IAP offers a broad range of research on polymers. About 250 employees work on biobased and synthetic polymers that meet the growing demands of our partners. The institute focusses on synthesis and modification of polymers (including process optimization and scale-up possibilities up to ton scale), polymer processing, structural characterization and material testing for plastics.

The Fraunhofer Cluster of Excellence “Circular Plastics Economy bundles the competencies of 6 Fraunhofer Institutes. In an inter-institute research structure they are researching how the sustainable transformation of an entire plastics value added chain can take place under principles of the circular economy using the example of plastic. The economic and social effects of a circular plastics economy in the coming decades is also analyzed and taken into account.

Antje Lieske is speaker at the 2022 edition of the Circular Chemistry Conference.

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