Recycling von Wintersportartikeln mit dem Fokus auf post-consumer Skischuhschalen

The aim of this thesis is to provide a comprehensive overview of the polymers used in winter sports equipment, their requirements, and key characteristics, and subsequently to analyze in more detail the mechanical recycling of post-consumer ski boots, with a focus on the ski boot shells.
In the first section of this work, interviews were conducted with manufacturers of winter sports hard goods and their suppliers on five selected use cases (ski, ski binding, ski boots, ski helmet, and ski poles). These interviews enabled a structured identification of the polymers occurring in the material stream that may be present during the collection of post-consumer winter sports articles for the recycling process. At the same time, key requirements for the use of recyclates in new products were identified. Based on these findings, the use case "ski boots" was selected for further investigations into recyclability.
The focus of the further analysis was on the two polymers most commonly used in ski boot shells, thermoplastic polyurethanes (TPU) and polypropylene/styrene-ethylene-butylene-styrene (PP/SEBS). As part of the investigations, the recovery of recyclate, the preparation of the polymers by means of compounding, the processing in the injection molding process, as well as the mechanical characterization based on the most relevant parameters for the winter sports industry were carried out. Tensile tests according to ISO 527-2 at -15 °C, 0 °C and +23 °C, flexural properties according to ISO 178 at +23 °C, Charpy notched impact bending tests according to ISO 179-1 at -20 °C, 0 °C and +23 °C, and Shore D hardness according to ISO 868:2003 at 23 °C were tested. Furthermore, the effect of increasing recyclate content on virgin TPU and the influence of compatibilizers on the processing and mechanical properties were examined. The use of a compatibilizer improved the handling of the recyclate during the compounding process. The results of the mechanical characterizations were then compared with the characteristic values of currently used virgin materials. It was shown that the examined recyclates meet key minimum requirements, such as a Shore D hardness ≥ 50, and that their deviations from the properties of virgin materials lie within ranges that are generally promising for reuse in the original product.