Enhancing 3D printing sustainability: Reinforcing thermoplastic polyurethane with recycled polyurethane foam for durable applications in orthopedic footwear

This study seeks to advance the realm of 3D printing through the exploration of fabricating polymer matrix composite objects using recycled materials, with a particular emphasis on bolstering durability. Characterization was carried out by integrating polyurethane foam (PUF) residues into thermoplastic polyurethane (TPU) composites at different concentrations (ranging from 3% to 10% wt/wt), which are frequently employed in 3D printing. The chemical functions were analyzed using Fourier-transform infrared spectroscopy (FTIR), while thermal stability was measured through thermal gravimetric analysis (TGA). The morphology characterized of the material via scanning electron microscopy (SEM) and density measurement identified that the surface roughness and void content of the PUF/TPU composite materials was a significant factor affecting the measured mechanical properties. Experimental results indicate that higher PUF content enhances filament properties and the resultant 3D printed products, showcasing a reduction in both the density and melt index of the produced filament by 15.9% and 34.4%, respectively, with the addition of 5% wt./wt. PUF residues to TPU. Additionally, there was a notable increase in Young's modulus of the produced filament by 79.9% and maximum stress by 12.7%, while elongation at break was reduced by 24.9%. Furthermore, the study highlights the sustainability advantages of utilizing recycled PUF, contributing to waste reduction and associated cost savings. Recycled PUF emerges as a cost-effective additive for synthesizing 3D polymeric materials, holding promise for diverse applications such as orthopedic footwear, leveraging the desirable attributes of TPU. Highlights Recycled (PUF)/TPU composites for 3D printing, enhancing durability. PUF content improves filament properties, reducing density and melt index. Young's modulus and maximum stress of produced filament increases. Utilizing recycled PUF reduces waste and promises sustainability.