ABSTRACT Nonwoven waste from new or postuse surgical and FFP2 face masks represents a complex multimaterial stream with significant upcycling potential. Material characterization identified PP and PE as the predominant components, with minor fractions of PET, cellulose fibers, and inorganic fillers. Rheology was used to classify different waste streams: postuse surgical masks exhibited low viscosity and negligible yield stress, making it suitable for injection molding; postuse FFP2 masks showed higher zero‐shear viscosity, pronounced shear‐thinning, and significant yield stress, ensuring filament stability and shape retention in material extrusion additive manufacturing; new surgical masks displayed intermediate viscosity and shear‐thinning, enabling smooth and anisotropic film production via extrusion. Blending strategies of postuse masks enabled tuning of rheological and mechanical properties: injection‐molded samples maintained homogeneous mechanical performances within ~20% deviation, while 3D‐printed blends exhibited surface roundness and roughness associated with postuse FFP2 content. Overall, mask‐derived nonwovens can be successfully upcycled into sustainable feedstock.
Battegazzore et al. (Sun,) studied this question.