Upcycled copolyester as a compatibilizer for mechanical recycling of PET/PBT/TPU ternary blends toward closed-loop recycling

초록

Mechanical recycling of mixed engineering plastics is often limited by phase separation and weak interfacial adhesion, particularly in polyester-rich waste streams containing poly(ethylene terephthalate) (PET), poly (butylene terephthalate) (PBT), and thermoplastic polyurethane (TPU). Here, we repurpose an upcycled PET/PBT/PTMEG random copolymer (PEBTG), previously developed as a standalone material platform, as a sustainable compatibilizer for melt-mixed PET/PBT/TPU ternary blends. Under a fixed blend composition of 1:1:1, the effect of PEBTG composition on morphology, crystallization, and tensile properties was systematically evaluated. Compatibilization increased the elongation at break from 298 +/- 74% to 494 +/- 28% and the toughness from 65 to 103 MJ m(-3), while maintaining the tensile strength within a practical range of similar to 29-36 MPa. In parallel, the macroscopic uniformity of the films improved, indicating substantial structural reorganization of the polyester-rich phase during melt processing. These results show that upcycled copolyesters can function not only as end-use materials but also as effective compatibilizers for improving the mechanical recycling of heterogeneous ester-based plastic blends for a circular and ecofriendly economy.

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