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Lisa-Cathrin Leitner, Thomas Steiner, Andreas Greiner, Ruth Freitag

Microplastics, 2025, https://doi.org/10.3390/microplastics4030059

Biodegradable plastics are increasingly proposed as environmentally friendly alternatives for disposable dishes or glasses in addition to their more conventional uses as foils and in bags. If produced from certified degradable materials, such items are expected to degrade rapidly during state-of-the-art composting. However, conditions prescribed for the testing and certification of materials differ from those typically applied in industrial composting, and operators of the corresponding plants have found that degradation is incomplete. In this study the degradation of commercially available biodegradable bags as well as disposable sparkling wine glasses was studied in a series of pilot-scale composting campaigns closely mimicking state-of-the-art composting conditions. The materials were characterized regarding their chemical composition, structure, and crystallinity, as well as the changes thereof throughout the process. Evidence is given that parameters such as crystallinity change significantly during composting, which may inhibit breakdown during the process and thus have unknown consequences for the subsequent environmental impact.