Abstract

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. 1

Keywords

Blends // Personal protective equipment // Polypropylene // Recycling // Sanitisation

Highlights

• The potential for recycling face masks is a topic worthy of further investigation. This study examines the potential for recycling polypropylene (PP) from 3-ply disposable face masks, with the objective of supporting the European Union and Italian government’s goals for a circular economy.
• Challenges in Polypropylene Recycling: It addresses the typical barriers to recycling PP, namely the low recycling rate, issues of degradation, and the challenges of separating PP from other polyolefins and additives.
• The impact of sanitisation and blending methods on the properties of recycled polypropylene (PP) and its potential for use in conjunction with virgin PP is assessed.
• The applicability of the recycling process to industrial settings is demonstrated through the modification of properties suitable for extrusion and additive manufacturing, without the need for layer separation.
  
  

Resources and links

• 📑 Full text (publisher version) 2