MECHANICAL AND CHEMICAL RECYCLING OF LEATHER WASTE INTO COMPOSITES SUITABLE FOR DIVERSE 3D PRINTING TECHNIQUES

Approximately 80% of processed leather is discarded as solid waste during production, highlighting the urgent need for sustainable valorization strategies. Mechanical and chemical recycling offer two promising pathways to repurpose this material. In this study, we investigate both approaches to recycling leather waste. Mechanical recycling was employed to develop a fully bio-based, circular, and 3D-printable composite alternative to vegetable-tanned leather. Leather waste particulate were incorporated as filler. The composite was engineered to mimic the mechanical properties of genuine leather and to be processable via extrusion-based 3D printing technique for customizable bio-leather accessories. To address the hygroscopic nature of leather solid waste and the challenges of its hydrolysis, we developed a straightforward method for producing leather hydrolysate. The hydrolysate can be employed as filler for a green matrix suitable for Direct Ink Writing and LCD vat photopolymerization 3D printing techniques. This study demonstrates a dual recycling strategy to transform leather waste into 3D-printable composites. The resulting materials exhibit promising tensile and viscoelastic properties, supporting their suitability for diverse additive manufacturing techniques. By bridging innovative recycling processes with advanced manufacturing technologies, this work lays the groundwork for leather upcycling and opens new horizons in sustainable material design.