Recycling of wind turbine blade powder into HDPE wood-plastic composites: Enhanced mechanical and flame-retardant properties via interfacial modification

To fully recycle the wasted wind turbine blades (rWTB) powder, its major components (glass fiber reinforced plastic (GFRP) and balsa wood (BW)) was incorporated into high-density polyethylene (HDPE) to prepare wood-plastic composites (WPC) with maleic anhydride grafted polyethylene (MAPE) as the compatibilizer. By varying the mass ratio of GFRP to BW, the mechanical properties, interfacial morphology and water absorption of rWTB/HDPE composites were systematically investigated. With the combination of 30 % GFPR and 10 %BW, the obtained H/30G10B composites exhibited the highest the tensile strength (27.73 MPa) and increased impact strength (21.85 KJ/m²) with the presence of 3 % MAPE. Scanning electron microscopy (SEM) images showed that MAPE improved the interfacial bonding between the filler and the HDPE matrix. To improve the fire resistance of HDPE composites, ammonium polyphosphate (APP) was further incorporated into H/30G10B sample. With the addition of 22 % APP, the best sample could reach a limiting oxygen index (LOI) of 36.8 %, V-0 rating in UL-94 and a decreased heat release in cone calorimetry. In summary, this paper provides a new method for resource utilization of rWTB, which can improve the performance of composites and avoid environmental pollution.