Title : Chemical and biological recycling strategies for polyurethane foams: Toward a circular footwear industry
Abstract:
Polyurethane (PU) is a polymer typically derived from non-renewable fossil resources, resulting in end products that are difficult to recycle and highly polluting. In response to these challenges, this work explores innovative strategies for the recycling and valorisation of polyurethane materials within the framework of the Circular Economy. Specifically, it focuses on the development of processes for the recycling of polyurethane materials, widely used in the footwear sector, through chemical and biotechnological recycling approaches.
The chemical recycling of polyurethane foams was performed through a glycolysis process using low molecular weight glycols as the glycolytic agent. This technique allows the efficient depolymerisation of PU waste and the recovery of polyols for subsequent reuse in the synthesis of new materials. The effectiveness of the depolymerisation process was evaluated and confirmed by Fourier transform infrared spectroscopy (FTIR) and determination of the hydroxyl number (OH index) of the products obtained, an essential parameter for their potential reuse in obtaining flexible foams.
In parallel, the biological recycling of PU foams was studied using three species of filamentous fungi: Aspergillus fumigatus, Aspergillus flavus and Alternaria alternata. Biodegradation was monitored by evaluating fungal growth and structural changes in the material. This line of research offers promising opportunities to identify optimal conditions and microbial systems capable of enhancing the biodegradation of polyurethane, contributing to more sustainable end-of-life solutions.
In conclusion, the RECIPOL project has successfully developed chemical recycling technologies for polyurethane foam waste, providing recycled polyols that can be reused in the synthesis of new polyurethane materials. At the same time, biological recycling studies using filamentous fungi have demonstrated the potential of fungal biodegradation as a complementary strategy for the valorisation of polyurethane waste. Therefore, the work carried out in this project lays the foundations for the recycling and valorisation of polyurethane waste, contributing to the implementation of circular economy systems in the sector.
