Experimental Characterization of Fibre-Based Composite Packaging and Its Implications for Recyclability

The transition towards a circular economy is reshaping multiple industrial sectors, including packaging. Within the European Union, increasing regulatory pressure is accelerating the need to reduce single-use plastic and ensure packaging recyclability. In this study, the main attention is given to flexible fibre-based composites, due to their growing relevance in sustainable packaging. Nevertheless, rigid fibre-based composites were also evaluated due to their recyclability challenges. The objective of this thesis was to evaluate the technical feasibility of replacing conventional plastic-based sachets with fibre-based composite alternatives, while maintaining functional performance and complying with new recyclability requirements. Six fibre-based composite materials were analyzed through laboratory characterization, pilot-scale production, and shelf-life evaluation. Mechanical properties were assessed alongside barrier performance, with particular attention to oxygen transmission rate and water vapor transmission rate. In parallel, the materials were evaluated through a theoretical recyclability assessment based on material composition and current design-for-recycling principles, following 4evergreen guidelines. The results indicate that fibre-based composites currently exhibit lower mechanical strength compared to conventional plastic references. Simultaneously, depending on specific laminate structures, fibre-based sachets can achieve optimal barrier performance and recycling compatibility with paper recycling mills. Overall, the findings suggest that fibre-based sachets cannot yet fully replicate the performance of conventional plastic sachets, and further material and structural development is required to achieve a balanced compromise between mechanical integrity, barrier performance, and recyclability under evolving regulatory constraints.