Silane-Assisted Interfacial Regulation of Recycled Wind Turbine Blade Powder-Reinforced Epoxy Composites

The stable crosslinked structure of glass-fiber-reinforced epoxy composites in end-of-life wind turbine blades complicates their recycling and reuse. Mechanically ground blade powder can be incorporated into new epoxy systems, but its heterogeneous surface composition and limited compatibility with the matrix restrict its reinforcing efficiency. In this study, sequential NaOH activation and KH560 treatment were used to regulate the surface characteristics of recycled wind-turbine-blade powder. FTIR and direct powder XPS measurements revealed changes in the hydroxylated silicate environment and the introduction of KH560-associated organic and organosilicon surface species. Representative SEM observations showed greater resin attachment and a more integrated local powder-matrix morphology after sequential treatment. At a fixed recycled-powder loading of 40 phr, corresponding to approximately 28.4 wt% of the total uncured mixture, EP-KH560 achieved mean flexural and tensile strengths of 67.00 and 38.81 MPa, respectively. These values were 47.8% and 57.1% higher than those of the composite containing untreated powder. Under the fixed formulation and processing conditions investigated, the results demonstrate that sequential NaOH/KH560 treatment improves the interfacial compatibility and comparative mechanical performance of recycled wind-turbine-blade powder/epoxy composites.