Investigation on the recyclability potential of vehicular brake pads

In this work, different fractions of material recovered from exhaust brake pads were mixed with a masterbatch used to produce low-metallic brake pads. The materials to be recycled came both from the friction material and the underlayer of the brake pad to assess the recycling of all the composite part of the exhaust brake pads through an end milling process. The tribological tests implemented on the pins demonstrated the technical feasibility of this recycling approach in a cradle-to-cradle perspective. A full mechanical characterization provided important indications for selecting the more promising compositions. Compression strength of the reference pins was retained up to a 30 ​wt% concentration of the recycled material; while above this value, a decrease in both the stiffness and the failure resistance was observed. Pin-on-Disc tribological tests on recycled pins containing powder recovered from the pad underlayer only highlighted an unstable and higher friction coefficient and specific wear coefficient with respect to the reference friction material. On the contrary, the wear behavior of the pins prepared using just recycled friction material was very close to that of the reference sample, as concerns the emission behavior of the particulate matter produced by the wearing out of the tribological samples.