Recycling of personal protective equipment: Sanitisation, degradation and polymer blend formulations

Despite being one of the most widely used polymers, polypropylene (PP) has a recycling rate of just 5%, mainly due to difficulties in separating it from other polyolefins and contained additives, as well as its tendency to quickly degrade during reprocessing and use. However, face masks, composed of pure PP without additives and designed for short-term use, offer a unique recycling opportunity. This research explores the recycling potential of PP from disposable face masks, focusing on how different sanitisation methods— ultrasounds and aqueous hypochlorous acid (HClO) solution—impact the material's properties. The research evaluates the extrusion reprocessing of both sanitised and unsanitised PP, in its pure form and when blended with virgin PP at different ratios (90/10, 70/30, 50/50 by weight), for potential applications such as cast film extrusion and additive manufacturing. Results highlight that different PP grades are used in the mask's layers for specific filtrations roles. However, the recycling process considered in this study did not separate these layers, simplifying industrial applicability. After sanitisation and extrusion processes, no evidence of chemical oxidation was found, but rheological analyses revealed polymer chain breakdown and reduced molecular weight. Blending the recycled polymer with virgin PP, modified rheological, thermal and mechanical properties with variations depending on the blend composition. Incorporating virgin polypropylene to enhance the performance of the recyclate demonstrates the feasibility of recovering a valuable material that, properly sanitised, retains properties suitable for industrial processes such as cast film extrusion and additive manufacturing. This approach underscores the potential of recycling strategies to convert discarded surgical masks from waste into valuable and make a significant contribution to the circular economy model.