Freeze–thaw recycling for fiber–resin separation in retired wind blades

The disposal of decommissioned wind turbine blades represents a growing economic loss and environmental concern due to the non-recovery of durable glass fiber-reinforced epoxy composites. Existing thermal and chemical recycling methods often require high temperatures and toxic chemicals, causing material degradation. Here, we present a novel freeze-thaw-based method for fiber-resin separation as an alternative. The process uses only water at human-safe temperatures, leveraging ice-induced expansion to disrupt the glass fiber-epoxy interface. Microscopic imaging and weight analysis revealed visible interface separation, with three-dimensional imaging showing a ~ 65% increase in crack volume and a ~ 32% rise in connected porosity after freeze-thaw treatment. Glass fibers retained up to 96% of their original mechanical properties, demonstrating minimal structural damage. Microplastics were easily removed through filtration, and the effluent water remained near-neutral with low organic carbon levels, meeting global water safety standards. These findings highlight freeze-thaw cycling as a sustainable route for efficient fiber-resin separation with minimal environmental impact.