Researchers from the Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, and the University of Nottingham Ningbo China have developed a new route for converting post-consumer polyethylene terephthalate (PET) waste into a high-performance epoxy toughening agent. The approach could provide a higher-value pathway for incorporating recycled plastic into advanced composite materials.
The researchers use a one-pot depolymerization-and-rebranching process to transform waste PET into hyperbranched oligomers (HBOs). These oligomers feature a highly branched molecular structure with numerous terminal hydroxyl groups, allowing them to disperse within an epoxy matrix and chemically integrate into the resin network during curing.
When just 0.3 wt.% of the PET-derived HBO was added to the epoxy, the resulting material recorded a 98.9% increase in impact strength. At the same time, the researchers reported that the modified epoxy retained its mechanical strength, transparency, thermal stability, and processability.
The toughening effect is linked to the formation of nanoscale structural heterogeneities within the cured epoxy. These chemically integrated domains help dissipate mechanical energy through mechanisms including localized plastic deformation, crack deflection, crack bridging, and microcracking. Together, these effects create a multiscale energy-dissipation network that improves the resin's resistance to impact.
Unlike conventional PET recycling approaches that may convert the material into lower-value intermediates, the researchers' method directly transforms waste PET into a functional additive for high-performance epoxy systems. The process has also demonstrated compatibility with different PET feedstocks and has been validated at the kilogram scale, indicating potential for further development toward larger-scale production.
The development could have implications for fiber-reinforced polymer composites, where epoxy resins are widely used as matrix materials. By incorporating a small quantity of a PET-derived toughener while maintaining the resin's other performance characteristics, the technology offers a route to combine plastic waste upcycling with improved composite durability.
The research demonstrates how waste polymers can move beyond conventional recycling pathways and become value-added components for advanced materials, supporting greater material circularity in the production of high-performance epoxy and composite systems.
Source: SAMPE China Insights | LinkedIn
