Influence of Application Conditions on the Magnetic Properties of Recycled Polymer-Bonded Magnets Based on Thermoplastics and Ferrite-Based Fillers

Several application possibilities exist in terms of polymer-bonded magnets, such as the sensors or smaller motors, for example, in the window operators of cars. Increasing demand and rising environmental awareness necessitate a higher understanding in terms of the possible recycling strategies for polymer-bonded magnets, especially in the context of a circular economy; post-consumer materials are barely available in terms of polymer-bonded magnets. This paper investigates the focused aging of polymer-bonded magnets based on thermoplastics and ferrite-based fillers via temperature and chemical treatment to reveal the post-industrial products representative of post-consumer products via fast aging. The changes in the dimension and the magnetic properties via these treatments are analyzed. Further, new samples are produced with 50 weight-% of recycled material to investigate the impact of the treatment on the magnetic properties of recycled samples. It was proven that both the dimension and magnetic properties were affected by the treatments. Unexpectedly, the magnetic properties increased with the fast aging based on the temperature treatment due to a so-called “snowball effect”. In addition, only the magnetic properties changed within the recycled material, where they reached about 100 mT and were about the same to 20% less relative to the ideal remanence BR value. With these investigations, the usability of the recycling strategy of reusing shreds in terms of thermoplastic-based polymer-bonded magnets with ferrite-based fillers was proven in terms of the post-industrial products representative of post-consumer products via fast aging.