Chemical Upcycling of PLA-Based 3D Printing Waste: An Effective Pathway toward Styrene-Free Polyester Resins.

Abstract

This study focusses on the valorization of polylactic acid (PLA) waste, including additive-containing materials (PLA+), generated by fused deposition modeling (FDM) 3D printing, which represents a growing environmental concern driven by the increasing adoption of FDM technologies. An efficient chemical upcycling strategy is presenting, enabling the direct transformation of 3D printing waste into value-added, styrene-free unsaturated polyester resins. Thermal depolymerization of PLA using diethylene glycol affords a low-viscosity intermediate, facilitating the efficient removal of fillers and pigments by simple centrifugation or filtration. The generality of the approach was demonstrated across a series of commercial PLA and PLA+ samples. The resulting glycolysate was successfully utilized as a renewable feedstock for the synthesis of itaconate-based polyester with tunable degree of unsaturation. Subsequent formulation with dimethyl itaconate enabled the preparation of room-temperature-curing resins. The optimized system exhibited a high glass transition temperature, good thermal stability, and favorable mechanical performance, including flexural strength of up to 74.9 MPa and a Young’s modulus of 2.32 GPa, highlighting the potential of this strategy for the development of sustainable polymer material.