Discarded masks turned into nanocomposites with carbon nanofillers

Researchers at the University of Engineering and Technology in Lahore, in collaboration with the Environmental Protection Department of the Government of the Punjab, have developed a method to transform discarded surgical masks and gowns into high-performance nanocomposites. These materials are reinforced with carbon nanotubes and graphene nanoplatelets, offering a valuable alternative to the original nonwoven polypropylene waste. This study, published in Polymer Bulletin, addresses the recycling challenges of nonwoven polypropylene, which is difficult to process due to contamination and mixed waste streams.

Led by Urwa Arshad and Sobia Naseem, the research team focused on enhancing the properties of recycled polypropylene by incorporating carbon-based nanofillers. These nanofillers are known for their stiffness and thermal resilience. The study explored whether these reinforcement effects, typically seen in virgin polypropylene, could be achieved with post-consumer waste. The researchers employed a dual-step processing method, dispersing the nanofillers in an aqueous medium using ultrasonication before combining them with polypropylene in a twin-screw extruder.

The study found that low loadings of 0.25 to 0.5 weight percent of nanofillers resulted in uniform dispersion and optimal mechanical performance. Higher loadings led to particle clustering and reduced tensile strength. Thermal analysis showed significant improvements in thermal stability, with the temperature of maximum degradation increasing by up to 53 degrees Celsius. This suggests that nanofillers act as barriers to degradation and heat sinks within the matrix, allowing the recycled material to withstand higher temperatures.

Further insights were gained through differential scanning calorimetry, which revealed a nucleation effect that increased the crystallization temperature of the recycled polypropylene. This effect suggests that the carbon surfaces facilitate faster and more complete crystallization, potentially leading to shorter molding cycles and more uniform crystalline morphology. Fourier-transform infrared spectroscopy confirmed strong interfacial interactions between the nanofillers and the polypropylene matrix, crucial for effective load transfer and reinforcement.

The study highlights the potential of using post-consumer personal protective equipment waste to create high-value nanocomposites, contributing to a circular economy. The process utilizes standard polymer manufacturing equipment, making it feasible for industrial adoption. While questions remain about the economics and long-term durability of the composites, the research provides a promising pathway for upgrading problematic plastic waste into thermally stable, mechanically reinforced materials.