Mechanische Recyclierbarkeit von TPU

In industrial processing of thermoplastic polyurethane (TPU), significant quantities of homogeneous production waste in the form of chips are generated during the machining of semi-finished products. Although TPU is thermoplastically processable and therefore mechanically recyclable, thermal disposal remains the predominant method of waste management. The aim of this study is to investigate the mechanical recyclability of TPU and to demonstrate a sustainable material recycling route as an alternative to incineration. To this end, cast TPU semi-finished products were shredded using a cutting mill to produce granulate, which was then vacuum-pressed at various temperatures to form test plates. Mechanical, thermal, rheological and chemical properties were evaluated over several recycling cycles. Particular emphasis was placed on the compression set, a key parameter for sealing applications. In addition, compounding experiments using base components were conducted to assess the targeted modification of the material structure. The results demonstrate that the investigated TPU is, in principle, mechanically recyclable. However, with an increasing number of recycling cycles, a gradual decline in elastic recovery and tensile strength was observed, accompanied by molecular structural changes, as evidenced by thermal, chemical and rheological analyses. Nevertheless, appropriate selection of pressing temperature and subsequent thermal post-treatment can stabilize the material quality. This work thus provides important insights into the material recycling of TPU and contributes to the development of sustainable recycling processes in the context of a functioning circular economy.