Valorization of End-of-Life Wind Blades in Alkyd Anticorrosion Coatings through an Open-Loop Chemical Recycling

This work proposes the development of modified alkyd coatings based on the open-loop chemical recycling of fiber-reinforced polymer (FRP) composites from end-of-life (EoL) wind turbine blades. Epoxy-based glass FRP composites are efficiently depolymerized by a catalyst-assisted mild solvolysis process using a biobased diol, achieving complete resin dissolution and recovery of clean fibers. The resulting organic recyclate, rich in hydroxyl-terminated epoxy-derived oligomers, is directly employed - without further purification or modification steps - as a reactive macromer for the synthesis of industrial alkyd resins. Modified alkyds containing up to 17 wt% recycled fraction are formulated into pigmented anticorrosive coatings and applied on steel substrates. Comprehensive characterization shows that recyclate contents up to 10 wt% do not adversely affect coating processability, curing, mechanical properties, outdoor durability, or corrosion protection, as confirmed by electrochemical impedance spectroscopy. These results demonstrate a viable and scalable route for the high-value reuse of chemically recycled FRP materials in protective coatings, enabling a synergistic circular economy link between the wind energy and coatings industries.