Transforming waste that is harmful to health and the environment by giving it a sustainable second life in a new production chain. This opportunity has been revealed by a study on asbestos conducted by Lorenzo Squitieri, an industrial PhD student at the spin-off Graftonica and a member of the research group led by Roberto Simonutti, Professor of Industrial Chemistry at the Department of Materials Science.
The researchers, coordinated by Michele Mauri, a researcher at the same Department, demonstrated how asbestos, a historically problematic material, can be reused as a useful component in the production of more easily degradable bioplastics.
In summary, thanks to thermal treatments developed by the group led by Giancarlo Capitani, Professor of Mineralogy at the Department of Earth and Environmental Sciences, asbestos can be transformed into a safe mineral powder. To make the process fully circular and economically sustainable, this powder was then reused as a filler, meaning that it was mixed with polylactic acid (PLA), a bioplastic widely used in industry and 3D printing.
The study, entitled “Upcycling detoxified asbestos cement as depolymerization regulating filler in polylactic acid (PLA) composites”, analysed two types of materials rendered harmless, called “red” and “green”, obtained through different processes. Drawing on Graftonica’s expertise in plastic processing techniques, these materials were incorporated into PLA and used for 3D printing with Fused Granular Fabrication (FGF) technology, which makes it possible to work directly with small granules, known as pellets, reducing costs and energy consumption.
The results showed that the “red” material can be incorporated into the bioplastic at up to 20 per cent by weight, while maintaining mechanical properties comparable to those of the reference material or slightly increasing rigidity. This makes it possible to create more durable and sustainable products, reducing the use of virgin raw materials and enhancing the value of a waste material that poses significant risks to the environment and human health.
The “green” material, by contrast, is prepared under conditions that enable it to break down PLA molecules through the brief application of a temperature of around 200°C. Although this variant slightly reduces the mechanical strength of the composites, it makes it possible to design bioplastics that can be degraded “on demand” at the end of their life, contributing to a more sustainable and controlled life cycle.
«This research shows in concrete terms how the treatment of hazardous waste is not only an environmental necessity, but also an opportunity to develop more responsible and sustainable materials,» said Lorenzo Squitieri, first author of the study.
«The collaboration between researchers from the two Departments — Materials Science and Earth and Environmental Sciences — combined with the agile and innovative approach of the spin-off, led to a result that is greater than the sum of its parts,» added Michele Mauri, researcher at the Department of Materials Science. «The most exciting moment came when the analysis of data that initially appeared to be incorrect instead revealed an unexpected ability to degrade PLA. Now that these properties have been demonstrated, we are working to involve new partners in the industrialisation process.»