Comparative Study of MAPP Compatibilization and H₂O₂ Surface Treatment for Recycled GFRP-Reinforced Wood-Plastic...

Recycled glass fiber-reinforced polymer (GFRP) powder from decommissioned wind turbine blades offers sustainable reinforcement for wood-plastic composites (WPCs), but its efficiency is limited by poor interfacial adhesion with the polypropylene (PP) matrix caused by surface epoxy residues. In this study, GFRP/WPCs with a fixed formulation of 15 wt% GFRP, 10 wt% wood flour, and 75 wt% PP were used to compare two modification strategies: MAPP compatibilization (1-7 wt%) and H₂O₂ treatment (5-30%). MAPP modification improved the mechanical properties of GFRP/WPCs, with the optimal concentration varying by property: flexural strength reached its maximum (75.45 MPa, +24.7%) at 1 wt% MAPP, while tensile strength (+9.2%), flexural modulus (+20.7%), and impact strength (+18.9%) were maximized at 3 wt% MAPP. H₂O₂ at 10% achieved higher strength gains (tensile: +23.65%, i.e., 26.7 MPa; flexural: +27.93%, i.e., 77.4 MPa; impact: +35.29%, i.e., 16.98 kJ/m²) but moderately reduced flexural modulus. FTIR confirmed up to 71.7% epoxy removal by H₂O₂, exposing cleaner fibers. Both modifications slightly lowered thermal decomposition temperatures but increased char residues and PP crystallinity via enhanced nucleation. SEM showed that MAPP created a compatible interphase, while H₂O₂ enabled direct mechanical interlocking. Surface free energy analysis revealed that MAPP increased polar components, whereas H₂O₂ increased dispersive components. Overall, MAPP offers simpler processing and balanced properties, while H₂O₂ provides superior strength at the cost of some stiffness-providing practical guidance for tailoring recycled GFRP/WPCs for construction and sustainable applications.