Zero-Waste Recycling of Fiber/Epoxy from Scrap Wind Turbine Blades for Effective Resource Utilization

The number of scrap wind turbines is expanding globally as the wind power industry develops rapidly. Zero-waste recycling of scrap wind turbine blades (WTB) is the key for wind power firms to achieve green and sustainable development on the premise of satisfying environmental protection criteria. In this work, the pyrolysis of fiber/epoxy composites obtained from scrap WTB in oxidizing inert atmospheres was investigated. Various characterization methods were employed to characterize the microstructure and chemical characteristics of the heat-treated fiber/epoxy and to reveal the pyrolysis mechanism. In addition, the heat-treated fibers/epoxy were used as reinforcing agents to investigate their impact on the elastic deformation of butadiene styrene rubber-based flexible composites, and the reinforcing mechanism was revealed. The results revealed that the constituents of fiber/epoxy composites were mostly fiberglass (SiO₂, CaCO₃) and cured epoxy resin, with covalent bonding being the interaction between the fiberglass and epoxy resin. The total weight of the epoxy resin in the fiber/epoxy composites was 22%, and the 11% weight loss was achieved at around 350 °C, regardless of the presence of oxygen; however, the features of heat-treated fibers/epoxy were associated with the pyrolysis atmosphere at a higher temperature. The pyrolysis products in inert atmospheres, with water contact angles of 58.8°, can considerably improve the tensile properties of flexible composites at the elastic stage. Furthermore, the flexible composite granules were prepared to plug large channels in sand-filled pipes, and the plugging rate had the potential to reach 81.1% with an injection volume of 5.0 PV. The plugging performance was essentially unaffected by water salinity, owing to the high stability of flexible composite granules in mineralized water. The findings of this study present a realistic route to the industrial application of fiber/epoxy, as well as a novel approach for encouraging the efficient use of scrap wind turbines on a large scale.