Sustainable tannery waste-based materials for additive manufacturing

The production and accumulation of leather waste, resulting from the tanning industry, has become an urgent environmental issue due to its detrimental impact on ecosystems, resource depletion, and landfill overcrowding. This work aims to develop PBAT/TPS with leather waste composite filaments suitable for FFF, and to evaluate their mechanical, thermal and biodegradation performance. The study involved the preparation of leather polymer composites (LPC) with different LWP volume contents (10%, 20%, 30%, and 40%) and subsequent evaluation through various tests. Tensile tests were conducted on both injected and printed specimens. The composite materials exhibited higher Young's modulus, doubling in value, and improved tensile strength at yield (8 MPa) compared to the pure PBAT/TPS matrix (6 MPa). However, the incorporation of LWP also led to a decrease in elongation at break, reducing flexibility. Scanning electron microscopy (SEM) images provided insights into the packing of printed layers, highlighting the presence of voids and poor layer adherence, which adversely affected the mechanical properties of the printed specimens. Thermal characterization was conducted using differential scanning calorimetry (DSC) to analyse the effects of LWP incorporation on the glass transition temperature (T g ), crystallization temperature (T c ), melting temperature (T m ), and degree of crystallinity (X c ). The results indicated a nucleating effect of LWP, as evidenced by the shift in X c values. Printed samples of both LPC and the PBAT/TPS blend were exposed to composting conditions and the degree of disintegration was assessed. Results prove that the addition of LWP to the blend does not influence the polymers’ ability to degrade, achieving over 90% disintegration after 90 days for LWP contents of 10 and 20%. To conclude this work, a case study was performed, creating interesting patterns inspired by the fashion industry.