Technical and environmental assessment of a circular economy scenario for end of life tires fibers used as reinforcement in plastic compounds

Automotive and tire markets are constantly increasing, with a huge quantity of end of life tires (ELT) that have to be managed each year to mitigate potential environmental issues. Thanks to the adoption of specific legislation about the waste management, most of the materials deriving from ELT are properly recovered, but there is still a room for improvement in particular for what regard the ELT fibers that are currently dismantled in landfills or incinerated. In this context, the present study aims to propose an innovative scenario for the management of ELT fibers, focused on the reuse of such material for the production of polypropylene (PP)-based compounds. The final objective is to validate this idea by verifying the technical feasibility, as well as to understand if and to what extent reuse of ELT fibers in plastic compounds leads to environmental benefits. From the technical point of view the proposed PP-based compound reinforced with 45% ELT fibers in weight resulted to have acceptable properties in terms of mechanical resistance and extrudability and good performance in terms of impact resistance that suggests the applicability in several applications as pallets manufacturing. From the environmental point of view, the Life Cycle Assessment (LCA) study at midpoint level suggests that the proposed scenario can be considered an interesting option against the other currently implemented EoL strategies, even if for some impact categories it does not lead to environmental benefits. However, by jointly considering potential damages on human health, ecosystems and resource depletion at endpoint level, the proposed reuse scenario can be univocally considered the most environmentally sustainable strategy for ELT fibers management.