Mortar blocks with addition of recycled polyurethane fibers (PUF) were subjected to abrasion using an original pin-on-disk tribometer in order to investigate the kinetic parameters and emission mechanisms of fine and ultrafine aerosol nanoparticles and the effect of the fiber concentration on the mechanical, tribological, and triboemission properties. Three different samples, referred as A (20% substitution level), B (40%), and C (60%) and a reference sample (Ref.) were analyzed for this study. The abrasion was performed in an environment chamber with filtered air using a stationary alumina sphere, 20 mm in diameter, which was pressed against the rotating sample using a dead weight of 1.3 kg. The sliding speed was 1 m s-1. A quantitative methodology was employed to assess the deposition rate, particle size distribution, and emissivity. The triboemission properties were correlated with the pore structure, morphology and tribochemical transformations of the particles and worn surfaces. The specific surface area, distribution of micro- and mesopore sizes, and skeleton density were evaluated through a comprehensive analysis involving three distinct methods: dynamic water adsorption, N2 adsorption, and He pycnometry. The mechanically affected zones were characterized using white-light confocal microscopy and Raman spectroscopy. The function of the particle size distribution exhibited two modes, with the most probable particle size falling within the range of 115-156 nm. Interestingly, the PUFs addition did not changed considerably the size of the particles. The aggregation of PUFs resulted in a gradual increase in the volume of pores, particularly mesopores, as well as an increase in the specific surface area. The study's results demonstrated a decline in the deposition rate of aerosol particles within the 10 to 60 nm aerodynamic diameter range as the concentration of PUFs increased. This observation strongly suggested the occurrence of direct emission of polymeric aerosol particles resulting from the abrasion of PUFs. The findings of this research provide valuable insights into the intricate relationship between material composition, particle size distribution, porosity, and emission kinetics.

The work was funded by the Ministry of Science and Innovation of Spain with the contribution from the European Regional Development Fund and the European Union NextGenerationEU / PRTR through the contracts PID2019-111063RB-I00, TED2021-129950B-I00 and PDC2022-134014-I00. Also, the support was provided by the Regional Government of Castilla y León (BU070P20).

Triboemission_data.xlsx DVS_data.xlsx N2_isotherm_data.xlsx He pycnometry_data.xlsx Raman_data.xlsx

Peer reviewed