Chinese Team Upcycles Waste PET into Epoxy Toughener, Increasing Impact Strength by 98.9%

en.Wedoany.com Reported - Researchers from the Chinese Academy of Sciences, the Ningbo Institute of Materials Technology & Engineering, and the University of Nottingham Ningbo China have developed a one-pot upcycling strategy that converts post-consumer polyethylene terephthalate (PET) waste into hyperbranched oligomers (HBOs) for use as epoxy resin toughening agents.

This "depolymerization-rebranching" process transforms waste PET into oligomers with a compact, highly branched structure and abundant terminal hydroxyl groups. According to the research team, this structure enables the oligomers to disperse uniformly within the epoxy matrix and covalently bond into the network during curing. At an addition level of just 0.3 wt.%, the PET-derived HBOs increased the impact strength of the cured epoxy resin by 98.9%, while maintaining the resin's processability, mechanical strength, transparency, and thermal stability.

The research team attributed the toughening effect to the formation of nanoscale structural heterogeneities within the epoxy network. These rigid, chemically bonded regions act as stress concentration points, promoting localized plastic deformation, crack deflection, and crack bridging, while also initiating microcracks. Together, these mechanisms form a multiscale energy dissipation network that enhances toughness without relying on the cavity-induced shear deformation typically associated with conventional hyperbranched polymers.

The process demonstrates applicability across different PET feedstocks and has been validated at the kilogram scale. By converting waste PET directly into functional epoxy additives, rather than conventional monomers or specialty chemicals, this approach can offer a higher-value pathway for plastic recycling while supporting the development of tougher, high-performance epoxy systems. The original source of this announcement is available from SAMPE China.