Recycling of discarded face masks for modification and use in SBS-modified bitumen

Since the outbreak of the COVID-19 pandemic, the discarded face masks have attracted widespread attention in society. In line with sustainable development, a physicochemical treatment method was used to recycle discarded face masks into styrene-butadiene-styrene (SBS) modified bitumen. Utilizing the highly adhesive polydopamine-polyethyleneimine (PDA-PEI) coating, it has improved the surface damage of the discarded face mask fibers (DFMF) caused by natural aging and mechanical fragmentation, simultaneously strengthening the connection between the fibers and bitumen. At 46 °C, the 2% embellish-face mask fiber (E-FMF)/SBS modified bitumen, compared to the 2%DFMF/SBS modified bitumen, exhibited improvements in complex modulus (G*), elastic modulus (G'), and loss modulus (G″) by 12.27%, 16.39%, and 13.35%, respectively. Furthermore, at 0.1 kPa and 3.2 kPa, the creep recovery rate (R) increased by 23.3% and 32%, and the average creep compliance (Jnr) decreased by 54.7% and 64%. It was demonstrated that DFMF adhered with the coating, were more effective in improving the mechanical properties, deformation resistance, and shear resistance of the bitumen. This approach enriches the application scenarios of discarded single-use face masks and supports environmental protection and road construction.